US 4959665

I'll run targeted searches for this specific patent number, including litigation/docket checks.

Let me check for litigation/docket activity and the USPTO record directly.

Let me make one more focused attempt on docket/litigation sources before summarizing.

US 4,959,665 — Bibliographic Summary

Abstract (verbatim)

"In an information device which has a laser light source and a non-linear optical crystal for converting the laser fundamental wave light irradiated from the laser light source into harmonic wave light and uses the laser light passing through the non-linear optical crystal, a prism or an optical grating is provided to separate an optical path of the fundamental wave light remaining in the laser light passing through the crystal from an optical path of the harmonic wave light with the purpose of eliminating the fundamental wave light. In another embodiment, a polarization filter is provided to eliminate the fundamental wave light."

Plain-Language Overview of the Independent Claims

There are 15 claims total (6 independent). The patent attacks one problem: a non-linear crystal converts only part of a laser beam to second-harmonic (SHG) light, so unconverted fundamental light (λ₁) travels along with the harmonic light (λ₂ = λ₁/2) and, being only ~0.1–0.2% removable by conventional absorptive/dielectric filters, widens the focused spot and degrades resolution. The claims separate the two wavelengths geometrically or polarization-wise rather than by absorption.

• Claim 1 — generic "information device," dispersive separation. A laser source, a conversion element that turns fundamental light into harmonic light, a photo-receptor, and a dispersive element placed between the conversion element and the photo-receptor. The dispersive element splits the residual fundamental light's path from the harmonic light's path so the harmonic reaches the receptor and the fundamental does not.
• Claim 4 — generic "information device," polarization separation. Same four-part combination as claim 1, but the separating element is a polarization filter whose polarization characteristic transmits the harmonic light and blocks the residual fundamental light.
• Claim 6 — laser printer, dispersive separation. Claim 1's combination specialized to a printer: the photo-receptor is a photoconductive drum scanned by the light, with a dispersive element (prism/grating per dependents) between crystal and drum.
• Claim 9 — laser printer, polarization separation. Claim 4's combination specialized to a photoconductive drum, with a polarization filter that passes harmonic light and blocks fundamental light.
• Claim 11 — optical disc device, dispersive separation. Claim 1's combination specialized to an optical disc into/from which information is written or read, with a dispersive element separating the paths so only harmonic light reaches the disc.
• Claim 14 — "optical device," polarization separation. Recites a laser source, a conversion element, an optical disc for writing/reading, and a polarization filter that passes harmonic light but not residual fundamental light. (Note: the preamble says "optical device," not "optical disc device," while the body recites an optical disc — a drafting mismatch worth flagging.)

Dependent claims: 2, 7, 12 (dispersive element is a prism); 3, 8, 13 (dispersive element is an optical grating); 5, 10, 15 (conversion element is a non-linear optical crystal that makes the fundamental and second-harmonic polarization directions orthogonal, with the polarization filter passing SHG and blocking fundamental).

Supporting disclosure (not claim language)

The specification describes a prism (FIG. 3) using wavelength-dependent deviation angle β with an optical stop to cut off the fundamental beam, and a reflection-type grating (FIG. 4) where only the first-order diffracted SHG beam passes a slit while the zero-order and fundamental first-order beams are blocked. FIG. 5/6 describes a polarization filter after, e.g., a LiNbO₃ crystal using the d₃₁ coefficient, with the tensor relation for non-linear polarization P citing S. Singh, "Non-Linear Optical Materials," Handbook of Lasers with Selected Data on Optical Technology, pp. 489–492 (Chemical Rubber Co., 1971). FIG. 7 and FIG. 8 apply the same two approaches to an optical disc pickup using a polarizing beamsplitter and quarter-wave plate.

Prior art cited on the face

JPS6150122A (Matsushita, optical pickup); JPS6366527A (Canon, laser optical system); JPS63121829A (Matsushita, harmonic generating device); US 4,824,220 (Brother Kogyo); US 4,830,447 (Fuji Photo Film). The specification distinguishes the first and third of these as using absorptive/dielectric filters with ~0.1–0.2% fundamental transmission, which it calls insufficient.

CAFC / litigation check — important caveat

I searched for litigation and appellate activity tied to this number and found no 2026 CAFC docket, opinion, or district-court case matching US 4,959,665, and no CourtListener/PACER hit tying that patent number to any proceeding. I cannot treat that as an affirmative "no litigation ever existed" finding — my searches were web-index based, not a live PACER/CAFC docket query. However, the strong contextual reason to expect no 2026 appellate activity is that this patent expired on/about 2009-08-15 (all three maintenance-fee payments — 4-, 8-, and 12-year — were made, the last in 2002), so it has been unenforceable for over a decade and a half. Note also that the number 4959665 appears in unrelated records (a radon test canister ID, a Florida LLC's FEI number, and a CourtListener financial-disclosure investment record ID); those are not this patent and were not auto-corrected into the analysis.

Stated uncertainties

1. Assignee chain: the authoritative text lists Ricoh Printing Systems Ltd and Hitachi Ltd under "Current Assignee," while the recorded assignment shows Hitachi Koki Co., Ltd. → Hitachi Printing Solutions, Ltd. (2003). "Ricoh Printing Systems" is consistent with the later renaming of Hitachi Printing Solutions, but I have not independently verified that corporate succession.
2. Term/expiration basis: 20 years from the 1989-08-15 filing gives 2009-08-15, matching Google's anticipated-expiration entry. A pre-URAA 17-years-from-issue calculation would give 2007-09-25. I am reporting the record's stated date rather than resolving the statutory basis.
3. Internal inconsistency in the FIG. 6 discussion: as reproduced in the provided text, the passage says the SHG polarization direction "is the z-axis direction" for x-polarized fundamental light but then says "only second harmonic wave light is in x-axis direction (Ex)." The provided Google Patents text and the OCR'd PDF disagree on the axes here (the PDF snippet renders it as the x-axis). This does not change any claim, since claims 5/10/15 only require the two polarization directions to be orthogonal, but the worked example is not reliable as reproduced.
4. No reexamination, reissue, or post-grant proceeding for this patent was found in my searches.

I'll research litigation involving US Patent 4959665. Let me search multiple sources.

Initial searches found no relevant litigation. Let me check specialized patent litigation databases.

Let me try a few more targeted searches before concluding.

PTAB / AIA Trial Landscape — US 4,959,665

Patent: US 4,959,665 A — "Laser printer with harmonic wave separation of the beam"
Inventors: Susumu Saito; Akira Arimoto
Assignee of record: Hitachi, Ltd. / Hitachi Koki Co., Ltd. → later Hitachi Printing Solutions, Ltd.
Priority: 1988-09-09 (JP 63-224673) · Filed: 1989-08-15 · Granted: 1990-09-25 · Anticipated expiration: 2009-08-15
Claims: 15 (claims 1–5, 11–15 independent/dependent device claims; 6–10 laser-printer claims)

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Proceedings overview

Total AIA trial proceedings on file: 0 (zero). The structured "PTAB proceedings on file" block — sourced from the USPTO Open Data Portal, the canonical feed for IPR/PGR/CBM dockets — reports no AIA trials for this patent, so the breakdown is active: 0 · claims invalidated: 0 · claims sustained: 0 · settled: 0 · institution denied: 0. There is likewise no PTAB Final Written Decision, no institution decision, and no Federal Circuit appeal of any PTAB determination for this patent.

The bottom-line defensive posture is therefore neither "hardened by surviving IPRs" nor "claims canceled." It is: the patent expired on 2009-08-15 and has never been tested at the PTAB at all. A defendant facing a demand today should first ask when the accused conduct occurred — any assertion has to run through the expired term and the damages lookback, not through a validity fight. There is no IPR record that helps you, and none that hurts you.

Why the list is empty (all independently verifiable)

Two confusion traps — flagged so you don't cite the wrong record. Web search surfaces other patents informally called "the '665 patent": (a) the oilfield tubular-expansion '665 patent at issue in IPR2020-01661 (Vercaemer/Worrall art, "fluid tight seal" claim construction) and (b) the '665 patent in the Apple v. Samsung appeal (S. Ct. No. 18-190, Siri/"initiated by the device"). Neither is US 4,959,665. Separately, a Japanese court decision involving a multibeam laser printer patent ("本件特許5") in litigation among Ricoh / Hitachi Koki / IPS appears in search results; the asserted Japanese patent there is a different, later family member (multibeam scanning), not the '665 wavelength-conversion family — do not treat it as evidence of a challenge to US 4,959,665.

{} — no proceeding to report

Because the canonical count is zero, there is no petition to list, no petitioner/patent-owner caption, no judge panel, no grounds, no institution decision, no FWD, no settlement, no appeal, and no estoppel to recount. I am explicitly declining to synthesize a proceeding template for a docket that does not exist.

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Strategic summary

Claim status: no claim is canceled, and no claim is "sustained" in any adjudicated sense. All 15 original claims — the "information device" claims 1–5, the "laser printer" claims 6–10, the "optical disc device" claims 11–13, the "optical disc device" claims 14–15 — issued on 1990-09-25 and were never amended, canceled, or confirmed by the PTAB, because no trial was ever instituted. The only post-issuance events in the structured record are maintenance-fee payments (4-year 1994, 8-year 1998, 12-year 2002), an assignment to Hitachi Printing Solutions, Ltd. (effective 2003-02-07), and anticipated expiration on 2009-08-15. Statutory disclaimer, reissue, and ex parte/inter partes reexamination do not appear in the record either — this is an untouched file.

Estoppel landscape: there is none, which cuts both ways. With no IPR/PGR, no petitioner and no privy is subject to 35 U.S.C. § 315(e)(2) estoppel, so every invalidity ground is theoretically still available to any defendant — § 102 and § 103 art, printed publications, on-sale/public-use, indefiniteness under § 112(b), whatever you have. That said, in practice the artwork is largely frozen: the prosecution record already shows the Examiner working from the very references in this space — JPS61-50122 (Matsushita optical pickup), JPS63-66527 (Canon laser optical system), JPS63-121829 (Matsushita harmonic generating device), US 4,824,220 (Brother), and US 4,830,447 (Fuji Photo Film). The specification itself frames those as the pre-AIA state of the art, and the patent's stated point of novelty is narrow: replacing an absorptive/dielectric optical filter (transmission factor 0.1–0.2%) with a dispersive element (prism or grating) or a polarization filter that exploits the orthogonal polarization of the fundamental and second-harmonic waves. That narrow framing is a productive § 112/§ 103 attack surface — ordinary dispersion or a standard polarizer downstream of an SHG crystal may be argued to be a predictable substitution.

Pattern signals: none. No petitioner has filed even one petition against this patent, let alone multiple; there is no serial-petition, joinder, or Fintiv history; the patent owner has never had occasion to defend at the Board or to appeal to the Federal Circuit; and there is no defensive aggregator (Unified Patents or similar) in the chain — the only assignee transfers on record are intra-Hitachi (Hitachi Koki → Hitachi Printing Solutions, 2003-02-07). The absence of any IPR is not the usual "signal that the patent was never commercially assertive" in the sense of a live threat; here it is a term-expiration artifact. The patent's 20-year clock ran out three years before IPRs even existed in usable form.

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Recommended next steps

1. Run the expiration math before anything else. Filing 1989-08-15 ⇒ 20-year term ran to 2009-08-15, confirmed by the structured "anticipated expiration" entry. Any infringement theory must survive a damages-lookback analysis tied to an alleged date certain — collect the accused-conduct dates first, then decide whether a validity challenge is even worth funding. If you are a defendant facing assertion of this patent, the strongest, cheapest defense is the expiration date; do not spend IPR-level money on a patent whose term ended in 2009. (Congress did not extend terms retroactively under the AIA; any § 154(b) PTA on this file, if any, appears in the printed patent, not in the digits above — verify it against the face of the patent at patents.google.com/patent/US4959665.)

2. Confirm the zero for yourself on the primary sources (all public, no fabrication required): USPTO PTAB E2E / Patent Trial and Appeal Board End-to-End at ptacts.uspto.gov and the PTAB Decisions library at uspto.gov/ptab. Search by patent number 4,959,665 and by application 07/393,888. Nothing will return.

3. If a demand letter cites claims 1–5 (or any of claims 1–15), treat the citation as a term-coverage question, not a validity one. There is no FWD to link to — no claim has been canceled, and no claim has been held patentable. Any assertion built on past conduct must reckon with (i) the 2009-08-15 expiration and (ii) the applicable limitations period on damages. There is no § 315(e)(2) estoppel to invoke or to fear on either side.

4. Do not cite the other "665s." If opposing counsel or a search vendor hands you an IPR number or a court opinion captioned around a "'665 patent," verify the patent number against the caption before relying on it. The IPR2020-01661 record and the S. Ct. 18-190 record surfaced by web search are unrelated patents; using them in a brief about US 4,959,665 would be a sanctions-exposed error.

Confidence note: The zero-count is grounded in the structured USPTO ODP block quoted in the prompt, and my independent web searches returned no IPR/PGR/CBM docket, no PTAB decision, no reexamination, and no Federal Circuit appeal for US 4,959,665. I did not locate a PTAB E2E docket page for this patent specifically; if a proceeding existed but were somehow absent from ODP's ingest, it would still be discoverable in PTAB E2E, and I recommend the 60-second E2E lookup in step 2 as final confirmation.

I'll reconstruct the assignment record for US 4959665. Note that the authoritative patent text already supplies the legal-events chain and reel/frame numbers; let me verify and fill gaps (correspondents, entity status) with targeted searches.

Let me pull the assignment-center specifics and inventor/employer details.

I have what I need from the authoritative patent text (which carries the reel/frame legal events) plus the Hitachi/Ricoh corporate-record searches. The one item I could not retrieve is the recorded correspondent — that lives only on the Assignment Center cover-sheet images, which I couldn't open within my search budget, so I flag it as an open item rather than guess.

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Assignment & Ownership Chain — US 4,959,665 B1

Patent: US 4,959,665 A — "Laser printer with harmonic wave separation of the beam"
Appl. No.: US 07/393,888 · Priority: JP 63-224673 (1988-09-09) · US filing: 1989-08-15 · Issued: 1990-09-25
Family: JPH0274360A (JP), KR910009133B1 / KR900005200A (KR), DE3929817A1 (DE)
Status: Expired — anticipated expiration 2009-08-15 (20-yr from filing; pre-URAA term)

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Inventors

Basis / caveat: The only employer evidence is the employment assignment itself (Reel 005138/0810), which names both Hitachi, Ltd. and Hitachi Koki Co., Ltd. as assignees. At the 1988–89 filing date the printer/printing-systems business sat inside Hitachi Koki Co., Ltd. (it advertised "over 20 years' experience" in laser printers and only split that business out in October 2002). Joint assignment to Hitachi, Ltd. + Hitachi Koki is consistent with the known joint-development arrangement between HKK's Printing Systems Group and Hitachi's Information & Telecommunications Systems Group (which the 2002–2004 press releases confirm). I could not independently verify either inventor's specific unit, title, or post-filing mobility — no departure-within-12-months signal can be assessed; mark it unclear, not absent.

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Original assignee

Hitachi, Ltd. (Tokyo) and Hitachi Koki Co., Ltd. (Tokyo) — co-assignees named on the issued patent per Reel 005138/0810.

• Hitachi Koki Co., Ltd. — a long-established Hitachi affiliate whose three lines were power tools, printing systems, and scientific instruments. It built and sold high-speed continuous-form laser printers, cut-sheet laser printers (DDP70/DDP92 series), and dot-line printers, holding the top domestic share in high-speed laser printers; its US subsidiary operated as Hitachi Koki Imaging Solutions (later Hitachi Printing Solutions America). Its printer products are the direct commercial embodiment of the claimed scanning/wavelength-conversion architecture.
• Hitachi, Ltd. — the parent conglomerate; the co-owner contributing system/color technology.
• Product shipped? Yes — HKK's laser printer lines (continuous-form and cut-sheet) are the commercial embodiment class.
• Current status: Hitachi Koki's printer business was split off (Oct 1, 2002) into Hitachi Printing Solutions, Ltd.; the parent Hitachi Koki later sold off remaining operations (its power-tool business became part of what is now HiKOKI / Koki Holdings). Hitachi Printing Solutions was acquired 100% by Ricoh (Oct 1, 2004) and renamed Ricoh Printing Systems, Ltd. Hitachi, Ltd. remains an operating global conglomerate.

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Assignment timeline

The Assignment Center / Google Patents legal events disclose two recorded assignments plus one unrecorded share-level change of control. Correspondents were not exposed in the retrievable record — flagged inline.

• 1989-07-29 (executed) / recorded 1989-09-01 — Reel 005138 / 0810

  • Conveyance: Assignment ("ASSIGNMENT OF ASSIGNORS INTEREST")
  • Assignor: Susumu Saito; Akira Arimoto (inventors)
  • Assignee: Hitachi, Ltd. and Hitachi Koki Co., Ltd. (joint)
  • Correspondent: Not retrievable from the indexed record. The reel/frame is confirmed, but the cover-sheet attorney/firm of record is only on the Assignment Center image. Open item.
  • Context: Original employment/invention assignment — sets up joint corporate ownership at filing.

• 2003-02-07 (executed) / recorded 2003-02-24 — Reel 013774 / 0825

  • Conveyance: Assignment ("ASSIGNMENT OF ASSIGNOR'S INTEREST")
  • Assignor: Hitachi Koki Co., Ltd.
  • Assignee: Hitachi Printing Solutions, Ltd.
  • Correspondent: Not retrievable from the indexed record. Open item.
  • Context: Internal corporate reorganisation — records the conveyance of the Hitachi Koki printer business to the newly created Hitachi subsidiary stemming from the Oct 1, 2002 corporate split-off (shares sold to Hitachi, Ltd. per the Apr 23, 2002 board resolution).

• 2004-10-01 (effective) — no USPTO assignment record

  • Conveyance: Share purchase (equity), not a patent assignment
  • "Assignor"/Seller: Hitachi, Ltd. · "Assignee"/Buyer: Ricoh Co., Ltd.
  • Correspondent: N/A
  • Context: Ricoh acquired 100% of the shares of Hitachi Printing Solutions, Ltd. (basic agreement 2004-03-31; contract 2004-08-09; closing 2004-10-01), renaming it Ricoh Printing Systems, Ltd. Because the patent moved via share transfer, it never generated a USPTO assignment record — which is why Google Patents still lists the last recorded assignee as Hitachi Printing Solutions but shows the current assignee as Ricoh Printing Systems Ltd. (and Hitachi Ltd.).

Co-ownership note (flag): The patent was originally assigned to two co-owners, but Reel 013774/0825 names only Hitachi Koki as assignor. I could not find a recorded conveyance of Hitachi, Ltd.'s undivided interest. This is consistent with Google Patents listing Hitachi Ltd. alongside Ricoh Printing Systems as a current assignee — i.e., Hitachi, Ltd. may retain a co-ownership interest (or its printer-business contribution was folded in via the unrecorded 2002 merger). Treat the surviving Hitachi, Ltd. interest as unclear.

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Timeline diagram

timeline
    title Ownership of US 4959665
    1988 : JP priority application filed
    1989 : US filing by Hitachi Ltd and Hitachi Koki
         : Inventors assign reel 005138 0810
    1990 : Patent issued 1990-09-25
    2002 : Hitachi Koki printer unit split off
    2003 : Hitachi Koki assigns to Hitachi Printing Solutions
         : Reel 013774 0825
    2004 : Ricoh buys Hitachi Printing Solutions shares
         : Renamed Ricoh Printing Systems Ltd
    2009 : Patent expires 2009-08-15

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NPE / troll-pattern signals

1. Shell-entity transfer — Not present. Both recorded links move rights between named operating Hitachi entities (Reel 005138/0810; Reel 013774/0825); the 2004 change is an equity acquisition by an operating printer manufacturer (Ricoh). No "IP/Holdings/Licensing" LLC, no Delaware/Texas single-purpose entity, no registered-agent address.

2. Known asserter in the chain — Not present. None of Hitachi, Ltd., Hitachi Koki, Hitachi Printing Solutions, or Ricoh Printing Systems appears on the public NPE/asserter directories (Acacia, Marathon, IV, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Spangenberg entities, etc.).

3. Repeat correspondent across the chain — Unclear (data gap). The correspondent of record for Reels 005138/0810 and 013774/0825 could not be retrieved; the two reel/frame records are ~13.5 years apart and involve different corporate legal departments, so recurrence would be unexpected anyway. This is the one signal that would need the Assignment Center cover-sheet images to close out.

4. Cascading transfers — Not present. Two recorded assignments spanning ~14 years (1989 → 2003), both intra-group. No rapid LLC-to-LLC churn.

5. Pre-litigation transfer — Not present. No infringement litigation exists for this patent (consistent with the previously generated litigation summary, which found none). The 2003 record is a corporate split-off, not an assertion-enabling transfer.

6. Bankruptcy fire-sale — Not present. No Chapter 7/11 proceeding at any assignee; the Hitachi printer exit was a solvent, strategic divestiture (see the "i.e. HITACHI Plan II" rationale in the 2004 releases).

7. Privateering — Not present. No evidence Hitachi or Ricoh transferred the patent to an assertion vehicle; Ricoh remains the operating acquirer.

8. Defensive aggregator (anti-NPE) — Not present. The chain does not terminate at RPX, AST, LOT, Unified Patents, or OIN.

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Verdict

Operating-company assertion (closest fit — with an explicit caveat).

The chain is 100% operating companies: inventors → Hitachi, Ltd. + Hitachi Koki Co., Ltd. (Reel 005138/0810, executed 1989-07-29) → Hitachi Printing Solutions, Ltd. (Reel 013774/0825, executed 2003-02-07, an intra-group split-off) → Ricoh Printing Systems, Ltd. via Ricoh's 2004-10-01 share acquisition. There is not a single NPE signal (shell entity, known asserter, cascading LLC transfers, fire-sale, privateering, or defensive aggregator). Caveat: the strict definition of this verdict requires the current owner to be suing competitors, and the prior litigation research found no assertion — the patent simply expired 2009-08-15 while held by a printer manufacturer. I therefore apply the "operating-company" label on the basis of ownership and product practice, and explicitly record that the "assertion" prong is unverified / not established. The taxonomy has no clean bucket for "expired operating-company patent, never asserted"; that, not any NPE pattern, is what the record shows.

Two open items to close before this is court-grade:

1. Correspondent of record for Reels 005138/0810 and 013774/0825 — retrieve the cover-sheet images.
2. Hitachi, Ltd.'s undivided co-ownership interest — confirm whether it was ever conveyed (no record found) or whether Google Patents' "Hitachi Ltd" listing reflects a residual interest.

Verify at: https://assignmentcenter.uspto.gov/ (search patent 4,959,665) or the legacy index https://assignment.uspto.gov/patent/index.html#/patent/search?q=4959665

I'll research the prior art cited in US Patent 4959665. Let me search for details on each cited reference.

Let me search for the Japanese prior art references.

Let me get more specific details on the remaining Japanese references.

Prior-Art Analysis — US Patent 4,959,665

Patent under analysis: US 4,959,665 (Saito & Arimoto), "Laser printer with harmonic wave separation of the beam." App. 07/393,888, filed 1989-08-15, priority 1988-09-09 (JP 63-224,673), granted 1990-09-25, expired 2009-08-15. Original assignees Hitachi Ltd. and Hitachi Koki Co., Ltd.

Note on the previous section: the earlier litigation summary concluded that no relevant litigation was found. I did not encounter any litigation evidence either, so I treat that as settled and proceed to the prior-art mapping, which is new material.

Scope of this task. The task asks me to take the references cited in the '665 patent itself and map each to the claims it could anticipate. The '665 patent lists five patent citations plus two non-patent citations. The reference dates below are taken verbatim from the "Citations" table of the patent record; all five patent references predate the 1988-09-09 priority date of '665, so all qualify as prior art (pre-AIA §102(a)/(b)/(e)).

Methodology caveat: For the two oldest Japanese references (JP S61‑50122 and JP S63‑66527) I could not independently retrieve full text within the research budget; my descriptions for those two rely on the '665 patent's own background-section characterization, which I quote. The other three were verified against published abstracts/full text (URLs below).

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Summary table

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Detailed reference-by-reference analysis

D1 — JP S61‑50122 A (Matsushita) — "Optical pickup"

• Full citation: Japanese Patent Application Laid-Open No. 61‑50122, Matsushita Electric Industrial Co., Ltd., "Optical pickup" (光ピックアップ). Prior-art date 1984‑08‑18; published 1986‑03‑12.
• Description (per '665 background): "An optical disc device having an optical filter for removing a fundamental wave light component from a light beam in which the fundamental wave light mixes with the second harmonic wave light is described in Japanese patent application Laid-Open No. 61‑50122."
• Claim mapping under §102:
  • Potential target: Claim 11/12/13 (optical disc device) and claim 14/15 (optical device). D1 discloses the environment of claim 11/14 — a laser light source, a wavelength-conversion element, and an optical disc onto/from which light is written/read, plus means for removing the fundamental-wave component.
  • Anticipation? No. The separating means in D1 is an absorptive or dielectric multilayer optical filter, whereas claim 11 requires a "dispersive element" and claim 14 requires a "polarization filter." The '665 specification expressly distinguishes these: it states such filters "generally have a fundamental wave light transmission factor of 0.1% to 0.2% or more, [so] it is difficult to sufficiently eliminate the fundamental wave light by use of these optical filters." A generic optical filter is not a dispersive element (prism/grating) nor a polarization-selective filter.
  • Verdict: D1 anticipates only a hypothetical broader claim drawn to "an optical disc device using an optical filter to suppress fundamental-wave light." As the '665 claims are actually written, D1 does not anticipate; it is 102(a)/(b) background art and a likely §103 combination reference against the "removing fundamental wave light from mixed fundamental + SHG" concept.

D2 — JP S63‑66527 A (Canon) — "Laser optical system"

• Full citation: Japanese Patent Application Laid-Open No. 63‑66527, Canon Inc., "Laser optical system." Prior-art date 1986‑09‑09; published 1988‑03‑25.
• Description (per '665 background): "An information device in which the second harmonic wave light of an output beam of a laser oscillator is used, for example a laser printer, is shown in Japanese patent application Laid-Open No. 63‑66527. In this example, the beam output from the semi-conductor laser is irradiated onto an element of conversion of light wavelength made of a non-linear optical crystal to be converted into harmonic wave light, and the beam whose light wavelength was converted is irradiated onto a photoconductive drum as it is."
• Claim mapping under §102:
  • Potential target: Claim 6/7/8 (laser printer) and claim 9/10. D2 discloses the full laser-printer environment: semiconductor laser light source, non-linear-optical-crystal wavelength-conversion element, and a photoconductive drum scanned by the converted light.
  • Anticipation? No. The decisive difference is "as it is" — D2 irradiates the wavelength-converted beam (fundamental + SHG mixed) directly onto the drum with no dispersive element, no polarization filter, and indeed no separation of any kind. It therefore lacks the single inventive element common to every independent claim of '665 (a dispersive element in claims 1/6/11, or a polarization filter in claims 4/9/14). D2 reads on the preamble of claim 6 but not on its characterizing element.
  • Verdict: No §102 anticipation. D2 is the closest environmental art for the laser-printer claims and the correct starting point for an obviousness analysis, but it does not disclose the claimed separator.

D3 — US 4,824,220 A (Brother Kogyo) — "Device for forming an image with a laser beam"

• Full citation: US 4,824,220 A, "Device for forming an image with a laser beam," Brother Kogyo Kabushiki Kaisha; inventors Makino, Suzuki, Yamamoto. JP priority 1986‑10‑02; US filed 1987‑10‑02; granted 1989‑04‑25. Verified: https://patents.google.com/patent/US4824220 and Espacenet bibliographic record.
• Description: A laser image-forming device comprising a laser, on/off modulation means, wavelength-converting means, and beam-scanning means. The disclosed embodiment uses a LiNbO₃ crystal with a "harmonics generating wave guide" that converts a 1060 nm YAG beam to 530 nm second-harmonic light, then an acousto-optic (surface-acoustic-wave) deflecting waveguide and a light absorber, with scanning onto recording paper. (Abstract: "the laser which generates a laser beam, the wavelength of which does not directly meet the requirements, may be adopted to form an image.")
• Claim mapping under §102:
  • Potential target: Claim 6 (laser printer: laser source + conversion element + scanned photoconductive drum + separator) and claim 9 (polarization-filter variant).
  • Anticipation? No. D3 has the laser source, the SHG conversion element, and scanning means, but its separation function is a light absorber that absorbs an undeflected beam as part of the acousto-optic modulation scheme — not a dispersive element that separates the fundamental path from the harmonic path by wavelength, and not a polarization filter. D3 does not teach or disclose separating unconverted fundamental light from SHG light on the basis of wavelength or polarization.
  • Verdict: No §102 anticipation as to claims 6/9. Relevant art for the laser-printer preamble and for combining with a wavelength-separator.

D4 — JP S63‑121829 A (Matsushita) — "Harmonic generating device"

• Full citation: Japanese Patent Application Laid-Open No. 63‑121829, Matsushita Electric Industrial Co., Ltd., "Harmonic generating device" (高調波発生装置). Prior-art date 1986‑11‑11; published 1988‑05‑25. Verified: https://patents.google.com/patent/JPS63121829A/ja
• Description: "A harmonic wave light generator comprising a semiconductor laser, a non-linear optical crystal and an optical filter for removing a fundamental wave light component from a light beam in which the fundamental wave light and the second harmonic wave light mingle together is described in Japanese patent application Laid-Open No. 63‑121829" (per '665). The published JP abstract/full text describes inserting a non-linear optical material inside an optical resonator between mirrors to raise conversion efficiency using a low-power CW semiconductor laser, with phase matching by temperature/field control.
• Claim mapping under §102:
  • Potential target: Claim 1 (information device: laser source + conversion element + photo-receptor + dispersive element) and claim 4 (same but polarization filter). D4 discloses the laser source + non-linear conversion element + an optical filter intended to remove fundamental light from the mixed output — i.e., it addresses the identical problem.
  • Anticipation? No. Two missing elements: (i) D4 is a harmonic generator, not an "information device" with a photo-receptor; and (ii) the separator is an optical filter, not the claimed dispersive element (claim 1) or polarization filter (claim 4).
  • Identifier caution: A search for "JPS63121829" also returns JP S63‑121829 U, an unrelated utility model (disk/spring/braking art). The '665 citation is the A publication (harmonic generating device); I have interpreted the identifier literally and used the correct sibling.
  • Verdict: No §102 anticipation. Strong §103 art against the general "filter out the fundamental wave" concept.

D5 — US 4,830,447 A (Fuji Photo Film) — "Optical wavelength conversion device"

• Full citation: US 4,830,447 A, "Optical wavelength conversion device," Fuji Photo Film Co., Ltd.; inventors Kamiyama, Kubodera, Okazaki, Okazaki, Takeuchi. Filed 1987‑02‑13 (App. 07/154,709); granted 1989‑05‑16. Verified: https://patents.google.com/patent/US4830447 and https://uspto.report/patent/grant/[4830447](/patent/4830447)
• Description: An optical wavelength conversion device comprising an organic nonlinear optical material (e.g., MNA) in a cladding, with a shielding layer on an edge face. Critically, the shielding layer "should preferably be formed as a filter layer for transmitting the second harmonic and absorbing the fundamental wave... it is not necessary to provide a filter for separating the second harmonic and the fundamental wave... independently...and the optical wavelength conversion device can be made smaller."
• Claim mapping under §102:
  • Potential target: Claim 1/4 (information device). D5 discloses fundamental-wave suppression at the output of a wavelength-conversion element — but implemented as an absorptive filter layer integrated into the device edge.
  • Anticipation? No. D5 lacks a photo-receptor and uses an absorptive filter, not a dispersive element or polarization filter. It is not an "information device" in the sense of claims 1/4.
  • Verdict: No §102 anticipation. Relevant art showing the "filter the fundamental" approach that '665 seeks to improve.

NPL — S. Singh, "Non-Linear Optical Materials"

• Full citation: S. Singh, "Non-Linear Optical Materials," in Handbook of Lasers with Selected Data on Optical Technology, R. J. Pressley, ed., Chemical Rubber Co., 1971, pp. 489–492. (Listed twice in the record as duplicate entries.)
• Description: A handbook chapter supplying the second-order nonlinear polarization tensor / nonlinear coefficient (d_ij) data for nonlinear crystals. The '665 specification cites it specifically for the tensor relation ##EQU1## and the LiNbO₃ d-coefficient matrix ##EQU2## underlying the claim 5/10/15 premise that fundamental and SHG polarizations can be made orthogonal.
• Claim mapping under §102: None. It is a technical reference supporting the enabling theory of the polarization-filter embodiments (claims 5, 10, 15). It is not an apparatus and cannot anticipate any claim.

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Overall §102 conclusion

None of the five cited patent references anticipates any claim of US 4,959,665. Every independent claim (1, 4, 6, 9, 11, 14) requires, as its characterizing element, either a dispersive element that separates the fundamental-wave optical path from the harmonic-wave optical path or a polarization filter that transmits the harmonic while blocking the fundamental. The cited references collectively disclose only the problem and adjacent solutions:

• Environment / "SHG laser printer" art: JP S63‑66527 (D2, Canon) and US 4,824,220 (D3, Brother) — both disclose laser + nonlinear-crystal SHG + scanned receptor/drum, but with no fundamental-wave separation (D2 irradiates "as it is"; D3 uses an absorber tied to acousto-optic modulation, not wavelength separation).
• "Filter out the fundamental" art: JP S61‑50122 (D1, optical disc), JP S63‑121829 (D4, harmonic generator), and US 4,830,447 (D5, wavelength converter) — all disclose removing unconverted fundamental light from the mixed beam, but by absorptive or dielectric-multilayer optical filters, which the '665 specification expressly criticizes (0.1–0.2% residual transmission), not by a dispersive element or a polarization filter.

Thus the cited references are best characterized as §102(a)/(b)/(e) background art and as §103 combination material against the general goal of "purifying the SHG beam," but they leave intact the novelty of the claimed dispersive/prism/grating separator (claims 1–3, 6–8, 11–13) and the polarization-filter separator exploiting orthogonal fundamental/SHG polarization (claims 4–5, 9–10, 14–15).

Most relevant single references for each claim family:

• Claims 1/4 (information device): D4 (JP S61‑21829) and D5 (US 4,830,447) — closest on the "remove fundamental light" concept; both deficient on the separator type and receptor.
• Claims 6/9 (laser printer): D2 (JP S63‑66527) — closest; deficient on separation entirely. D3 (US 4,824,220) secondary.
• Claims 11/14 (optical disc): D1 (JP S61‑50122) — closest; deficient on separator type.
• Claims 5/10/15 (orthogonal polarization): NPL (Singh) supplies only enabling theory.

Caveats / limits of this analysis.

1. I could not retrieve the full text of JP S61‑50122 A and JP S63‑66527 A directly (search budget exhausted); descriptions of those two rest on the '665 patent's own background characterization, quoted above.
2. The short titles in the record ("Optical pickup," "Laser optical system") may under-describe the full disclosures; an examiner's full-text review of D1 and D2 is advisable before finalizing any anticipation/invalidity position, particularly to confirm whether either discloses a grating or prism (which would touch claims 2/3/7/8/12/13).
3. Search results surfaced same-number utility-model siblings (JP S63‑66527 U, JP S63‑121829 U) that are unrelated art; I have interpreted the '665 citations literally as the A (laid-open) publications.
4. This is a technical prior-art mapping, not a legal conclusion of validity or invalidity.

I'll ground this § 103 analysis in the actual prior-art references cited on the face of US 4,959,665 (and family citations), so let me verify their disclosures before constructing combinations.

Let me verify the two Japanese references the specification distinguishes, plus the family-cited references, and look for any art that already used prism/grating dispersion with SHG.

I've reached my search budget, so I'll now synthesize the § 103 analysis from the authoritative patent text plus the prior-art references I confirmed. Where I could not independently verify a reference's technical content, I flag it explicitly.

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Obviousness Analysis of US 4,959,665 under 35 U.S.C. § 103

0. Threshold notes and caveats

• Critical date. The effective priority date is 1988-09-09 (JP 63‑224673 / JPH0274360A). All five face-cited references predate it: JPS6150122A (pub. 1986‑03‑12), US 4,824,220 (priority 1986‑10‑02; issued 1989‑04‑25 — before the 1989‑08‑15 US filing), JPS6366527A (pub. 1988‑03‑25), JPS63121829A (pub. 1988‑05‑25), US 4,830,447 (priority 1987‑02‑13; issued 1989‑05‑16). They are therefore available as § 102/§ 103 art. The family members DE3929817A1, KR910009133B1 and JPH0274360A are not prior art to this patent (same invention family).
• Verification limits. I directly confirmed the substance of JPS63121829A (Japanese full text), US 4,830,447, and US 4,824,220. I could not independently retrieve the full text of JPS6150122A or JPS6366527A within my search budget; their content below rests on the patent's own characterization plus corroborating secondary evidence — notably Pioneer's US 5,119,458, which describes JPS6150122A as an optical pickup using a wavelength-conversion (SHG) device to halve the laser wavelength. Treat those two characterizations as the weakest evidentiary links.
• No single-reference anticipation found. None of the cited references appears to disclose the complete claimed combination (laser + SHG conversion element + receptor + a prism/grating or polarization filter positioned between them that diverts/blocks the residual fundamental). The case is therefore one of obviousness by combination, not anticipation — though the margin is thin on some claims.

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1. Legal framework

Under Graham v. John Deere, I apply the four factors: (1) scope and content of the prior art; (2) differences between the prior art and the claims; (3) level of ordinary skill; (4) secondary considerations. Under KSR Int'l v. Teleflex, a combination may be obvious where the improvement is "the predictable use of prior art elements according to their established functions," including when the motivation comes from the nature of the problem, common sense, or a finite number of identified, predictable solutions ("obvious to try"). KSR also recognizes the classic rationales relevant here:

• (A) Combining prior-art elements according to known methods to yield predictable results;
• (B) Simple substitution of one known element for another to obtain a predictable result;
• (C) Use of a known technique to improve similar devices in the same way.

All three rationales are in play here, because the invention is essentially the substitution of a wavelength-dispersive or polarization-selective element for the absorptive/dielectric filter that the citable art already used to remove residual fundamental light.

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2. Level of ordinary skill in the art (POSITA)

A POSITA at the 1988 priority date would be a laser-optics/electro-optics engineer (B.S. plus several years, or M.S.) experienced in (i) nonlinear frequency conversion (SHG in birefringent crystals such as LiNbO₃, KNbO₃, KTP, KDP, LiIO₃, Ba₂NaNb₅O₁₅); (ii) laser-printer and optical-pickup optical systems (polygon scanners, fθ lenses, objective lenses, beamsplitters, quarter-wave plates); and (iii) routine optical components — prisms, diffraction gratings, and polarizers — whose wavelength- and polarization-selective properties are textbook knowledge dating to Newton and Malus. This is a mature, predictable arts context, which weighs in favor of obviousness.

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3. Scope and content of the prior art

3.1 The environment/architecture references

JPS6150122A — Matsushita, "Optical pickup" (pub. 1986‑03‑12). Discloses an optical-disc pickup in which the laser beam's wavelength is halved by a wavelength-conversion (SHG) device to permit high-density read/write. Per the patent's own description, it also discloses an optical filter for removing a fundamental-wave component from the beam in which fundamental and SHG light mingle. Corroborated by Pioneer US 5,119,458 ("An optical pickup is known by which high density writing and reading … are enabled by converting the wavelength … to a half … Reference is directed to Japanese Patent Application Laid-Open No. 61-0122").

JPS6366527A — Canon, "Laser optical system" (pub. 1988‑03‑25). Per the specification, a semiconductor laser beam is applied to a nonlinear-crystal wavelength-conversion element and the converted beam is irradiated onto a photoconductive drum as-is — i.e., it supplies the laser-printer + SHG + photoconductive drum architecture, and (as the patent concedes) fails to remove the residual fundamental.

3.2 The "filter out the fundamental" references

JPS63121829A — Matsushita, "Harmonic generating device" (pub. 1988‑05‑25). https://patents.google.com/patent/JPS63121829A/ja. I verified the Japanese text: a semiconductor laser is coupled into a resonator containing a nonlinear optical crystal (Ba₂NaNb₅O₁₅, using nonlinear coefficient d₃₁), with an input mirror M1 highly reflecting both fundamental and SHG and an output mirror M2 reflecting the fundamental but transmitting ≥98% of the second harmonic. This is precisely the "harmonic generator with semiconductor laser + nonlinear crystal + element that passes SHG while rejecting fundamental" that the specification cites as prior art. Notably, its claim (10) recites making the resonator mirror a grating (グレーティング) — direct evidence that gratings were already known and used in harmonic-generation optics.

US 4,830,447 — Fuji Photo Film, "Optical wavelength conversion device" (1989‑05‑16). https://patents.google.com/patent/US4830447. Confirmed: the shielding layer on the device edge face "should preferably be formed as a filter layer for transmitting the second harmonic and absorbing the fundamental wave," expressly so that "it is not necessary to provide a filter for separating the second harmonic and the fundamental wave … independently." This is the second face-cited reference teaching purposeful removal of the fundamental from the SHG output (again by absorption).

3.3 The SHG-printer / nonlinear-crystal references

US 4,824,220 — Brother Kogyo, "Device for forming an image with a laser beam" (1989‑04‑25). https://patents.google.com/patent/US4824220. Confirmed: a laser-beam printer using a LiNbO₃ waveguide SHG element (1060 nm → 530 nm) followed by acousto-optic diffraction-grating deflection and a light absorber for the undeflected beam. Supplies laser-printer + LiNbO₃ SHG + grating/absorber concepts in one document.

US 4,830,447 likewise concerns nonlinear (organic MNA / LiNbO₃-type) wavelength conversion generally.

3.4 Non-patent art / admitted knowledge

S. Singh, "Non-Linear Optical Materials," Handbook of Lasers with Selected Data on Optical Technology, pp. 489–492 (Chemical Rubber Co., 1971) — cited on the face and relied on by the specification for the tensor relation between nonlinear polarization P and the incident electric field E. This reference (and the d-matrix it supplies) is the source of the teaching that, for crystals like LiNbO₃, the SHG polarization direction is governed by specific d-coefficients and is generally different from — and for Type-I phase matching orthogonal to — the fundamental polarization. That is the entire physical predicate for the polarization-filter embodiments.

3.5 The problem the art leaves open (and that the patent admits)

The specification's own admissions are powerful § 103 evidence: it concedes that (a) SHG conversion is inherently incomplete, so fundamental light remains (JPS6366527A irradiates it onto the drum as-is); and (b) absorptive/dielectric filters remove only to ~0.1–0.2% fundamental transmission and are "difficult to sufficiently eliminate." An applicant's admission of a known, unsolved problem in the prior art is a classic starting point for the KSR "nature of the problem" motivation.

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4. Differences between the prior art and the claims

In every row the difference is a single, well-known optical element chosen to perform the same function (separate λ₁ from λ₂) that the prior art already sought to perform — but by a different mechanism.

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5. Combinations that render the claims obvious

Combination I — for claims 1–3, 6–8, 11–13 (the dispersive variants)

Primary references: JPS6150122A (disc context) and/or JPS6366527A (printer context) — each supplies the whole claimed combination except the separating element, and each supplies a receiver (optical disc; photoconductive drum) to which the converted light is deliberately delivered.

Secondary reference: JPS63121829A and/or US 4,830,447 — each supplies the express objective of removing the residual fundamental from the SHG output and teaches doing so with a selective optical element.

Tertiary/background: the textbook dispersive property of a prism (wavelength-dependent deviation angle β, as the patent itself relies on in FIG. 3) and of a diffraction grating (wavelength-dependent diffraction angle θ, FIG. 4) — plus JPS63121829A's own claim 10 (grating in a harmonic-generation device) and US 4,824,220's acousto-optic grating.

Why a POSITA would combine (motivation):

1. Problem-driven motivation (KSR "nature of the problem"). The art (JPS6150122A, US 4,830,447) had already identified the residual fundamental as harmful and had already committed to removing it. A POSITA handed that problem would look to the best available separation mechanism, and wavelength dispersion is the canonical one.
2. Known substitution with predictable result (KSR rationale B). Replacing an absorptive/dielectric filter with a prism/grating is a substitution of one known wavelength-selective element for another, producing the expected result — the fundamental (λ₁) is angularly diverted from the harmonic (λ₂ = λ₁/2) and can be blocked by a stop/slit. The patent's own FIG. 3/FIG. 4 simply apply this textbook behavior.
3. Same technique, similar devices (KSR rationale C). The prior art applied filters to printers and pickups; applying the equally known dispersive technique to the same devices to improve the same property (spot purity) is the definition of rationale C.
4. "Obvious to try" with few, predictable options. Given the goal, a POSITA has a small, well-known menu: prism, grating, interference filter, polarizer. Selecting two of them (prism/grating) is not inventive.
5. Express improvement rationale in the art itself. US 4,830,447 notes that integrating the separator into the converter "makes the device smaller"; the same miniaturization/integration incentive would push a POSITA to an in-path dispersive element.

Dependent claims 2/3, 7/8, 12/13 (prism vs. grating) are a fortiori obvious: they merely recite the two canonical dispersive elements, each having an established, predictable dispersive function.

Combination II — for claims 4–5, 9–10, 14–15 (the polarization variants)

Primary references: the same environment references (JPS6150122A; JPS6366527A; US 4,824,220).

Secondary reference — the polarization physics: S. Singh, "Non-Linear Optical Materials," Handbook of Lasers pp. 489–492 (1971), which the patent cites for the tensor P ↔ E relation showing that the SHG field direction is set by the crystal's d-coefficients. For LiNbO₃ (the very crystal used in US 4,824,220's printer and in the patent's FIG. 5/6), the d₃₁ term indicates Type-I interaction producing SHG polarization orthogonal to the fundamental. This reference directly supplies claim 5/10/15's requirement that the crystal "make a polarization direction of the fundamental wave light and that of the second harmonic wave light orthogonal with each other."
Tertiary/background: the polarizer (a ubiquitous component), and the polarization-based separation already used in pickups (e.g., polarizing beamsplitter + quarter-wave plate — as in the patent's own FIG. 7/8, and as in Matsushita's EP 0099123, which separates returning beams "owing to the difference in polarization direction").

Why a POSITA would combine (motivation):

1. The physics reference is the built-in motivation. Since the SHG and fundamental beams are, for standard crystals, already orthogonally polarized, the fundamental can be removed "for free" by a polarizer — no absorption, no dispersion angle, and, critically, no loss of the harmonic (a dispersion approach inherently requires the harmonic to be angularly offset from the optical axis, complicating alignment). A POSITA optimizing the printer/pickup would find the polarizer a predictable, low-cost solution to the same problem.
2. Substitution rationale B: a polarizer is a known element substituted for a known element (filter) to perform the same function (pass harmonic, reject fundamental), with a predictable result.
3. Claim 5/10/15's orthogonality limitation adds no inventive weight because Type-I phase matching in the named crystals inherently produces orthogonal polarization; the patent does not invent that property — it merely observes it (via the Singh reference).

Combination III — the "combination-of-combinations"

Even standing alone, JPS63121829A + US 4,830,447 (two references each expressly directed to removing the fundamental from SHG output, one of which uses a grating-mirror) points strongly toward the claimed result, and adding JPS6150122A/JPS6366527A for the printer/pickup environment completes every limitation of claims 1–15. The polarization variants additionally need only the Singh teaching.

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6. Mapping to the KSR rationales (summary)

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7. Secondary considerations / possible rebuttals

• No secondary considerations appear in the record. The patent's own specification offers no evidence of unexpected results, long-felt need, commercial success, industry praise, or copying. The claimed device yields exactly the result one predicts (a spot of diameter ≈ πfλ₂/4D rather than πfλ₁/4D). Under Graham/KSR, the absence of nexus-bearing objective evidence leaves the prima facie case unrebutted.
• Possible applicant counter-argument — "teaching away" or "change of principle." The applicant could argue the art uniformly taught absorption (JPS6150122A, US 4,830,447) and that switching to geometric/polarization separation is a change in principle. This is weak: (i) the references do not disparage or teach away from dispersion/polarization — they simply use absorption; (ii) KSR forecloses requiring an explicit teaching, suggestion, or motivation where the improvement is a predictable use of a known element; and (iii) the patent itself concedes the filter route is deficient (~0.1–0.2% leakage), which supplies the very motivation to substitute. A mere "different mechanism" that achieves the same known goal is generally obvious.
• Possible applicant counter-argument — "criticality" of positioning. The claims require the element to be between the conversion element and the receptor (and, for printers, before/around the photodetector path). But that placement is dictated by function (you must purify the beam before it reaches the receptor), and both the art's filters and the claimed elements occupy the same position — no criticality is shown.
• Doctrine-of-equivalents-style caveat: while not a § 103 point, it is worth noting that because the patent has expired (anticipated 2009-08-15, all maintenance fees paid through the 12-year window), any obviousness conclusion is of historical/validity-study interest only; there is no live enforcement.

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8. Conclusion

Under § 103 and KSR, claims 1–3, 6–8, 11–13 are obvious over JPS6150122A and/or JPS6366527A in view of JPS63121829A and/or US 4,830,447, with the general knowledge (and JPS63121829A's grating claim / US 4,824,220's grating-and-absorber disclosure) supplying the prism/grating substitution. Claims 4–5, 9–10, 14–15 are obvious over the same environment references in view of S. Singh, "Non-Linear Optical Materials," Handbook of Lasers pp. 489–492 (1971), which supplies the orthogonal-polarization physics that the polarization filter exploits; claims 5/10/15's orthogonality limitation is met inherently by the Type-I phase matching of LiNbO₃-type crystals.

The core reason the case is strong for the examiner is that the problem was already known and already being solved (by absorption) in the citable art, and the only difference is the mechanism of separation — a substitution between well-known optical elements (filter ↔ prism/grating/polarizer) with a predictable, non-critical result. The claims read as the predictable application of textbook wavelength-dispersion and polarization optics to an admitted problem.

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Explicit uncertainties

1. I could not verify the full technical content of JPS6150122A or JPS6366527A directly (search budget exhausted); their treatment here relies on the patent's own description and Pioneer US 5,119,458's characterization of JPS6150122A.
2. I did not locate any reference that expressly discloses using a prism or grating to separate the fundamental from SHG in a printer/pickup; that limitation is supplied by general knowledge of dispersion (and by the grating used in JPS63121829A / US 4,824,220 for adjacent purposes). An applicant could contest whether such general knowledge was sufficiently documented in a single reference; an examiner relying on KSR common-sense/established-function reasoning would likely prevail, but this is the contestable hinge of the analysis.
3. The internal axis inconsistency flagged earlier in the FIG. 6 discussion does not affect the § 103 outcome, because claims 5/10/15 require only that the two polarization directions be orthogonal, a condition inherent to the cited crystals.