US 4651200

I'll search for this specific patent number across the sources you named.

US 4,651,200 — Summary

Caveat up front: I could not retrieve any USPTO litigation record or any Court of Appeals for the Federal Circuit 2026 docket naming this patent. Targeted searches for "4651200"/"4,651,200" combined with CAFC/2026 returned no hits. My docket search is therefore incomplete or negative, not proof that no such proceeding exists. Everything below is grounded in the patent text itself plus the family/bibliographic data returned by search.

Bibliographic data

A contemporaneous New York Times item (March 21, 1987) confirms the grant: "Professor Ledley… was granted patent 4,651,200 this week for the double-power lens."

Abstract (as issued)

A split-image, multi-power microscopic image display system and method wherein the image of an object positioned on a slide is split into two optical paths, and is magnified to a varying degree in each optical path, the resulting respectively magnified images being displayed on respective monitor devices. The initial optical path includes an objective and a splitter; the paths of lower magnification and higher magnification each include a TV camera and a TV monitor, and may include various optical elements in accordance with the four disclosed embodiments. Further features of the invention include the following: provision of a microcomputer with data entry means, and respective mixers disposed between the TV cameras and their monitors for insertion of identifying information into the video signal, with subsequent display on the monitors of the identifying information and the image of the object being microscopically viewed; provision of a photographic printer for producing a hardcopy record of the image viewed; and provision of a lens switching arrangement for selection of various objectives without the necessity of refocusing after a lens is switched into position.

Independent claims in plain language

Claim 1 — Method, "increase magnification in one path" (base case). Take a microscope objective that magnifies the specimen at a first power. Split that optical output into two paths. In the first path, add magnification so the output is at a second (higher) power, and feed that to a first camera producing a video signal at the second power. In the second path, bend the output (claimed as passing through a prism in dependent claim 2) toward a second camera producing a video signal at the first power. Process both video signals to display two images of the same object at the two different magnifications. Note this is the low-power objective → magnify in path 1 architecture of the second/fourth embodiments, not the demagnifying first embodiment.

Claim 7 — System, mirror of claim 1. Same elements as claim 1 in apparatus form: objective lens (first magnification); splitting means; magnifying means in the first path (dependent claim 8: a diverging lens); a first camera in the first path; a second camera receiving the bent second output (dependent claim 9: the bending element is a prism at the end of the second path, adjacent the second camera); and display means showing both images.

Claim 17 — Method, "underscanning" variant. Same split-path setup, but instead of adding a magnifying optic in the first path, the first camera is operated in a reduced-scanning mode so that it effectively further magnifies the first optical output to yield the second (higher) magnification. The second path is still bent (claim 18: prism) to the second camera. This corresponds to the third embodiment, where the specification describes underscanning by a 5:1 ratio achieved by scaling horizontal scan-line length and vertical sweep distance to approximately 0.4472 of their unadjusted values.

Claim 23 — System, mirror of claim 17. Apparatus counterpart: the first camera in the first path is operated in a reduced-scanning mode to effectively further modify the first output and produce a video output at the second magnification; second camera plus bending means (claim 24: prism) produce the first-magnification video output; display means show both.

Claim 32 — Method, "two magnifying paths from a low-power objective." Provide an objective whose power is less than both target magnifications. Split its output into two paths. Magnify the first path's output to reach the first magnification (claim 32 requires increasing magnification of both paths) and magnify the second path's output to reach the second magnification (claim 33: the second path's magnifier is a Barlow lens). Then camera 1 produces video at the first magnification; the second (magnified) output is bent (claim 34: prism) toward camera 2, which produces video at the second magnification; both are displayed. This is the fourth embodiment.

Claim 39 — System, mirror of claim 32. Objective lens at a given magnification lower than both targets; splitting means; first and second magnifying means in the two paths (claim 40: first is a diverging lens; claim 41: second is a Barlow lens); two cameras producing the respective video outputs; bending means (claim 43: prism) before the second camera; display means.

Cross-cutting dependent features

• Data overlay (claims 3, 11–12, 19, 26–27, 36, 44–45): mixers combine either/both camera video outputs with analog representations of operator-entered information, using operator input means (keyboard) and processing means (microcomputer) — the microcomputer example being Imaging Technology MFB-512-8-4-M and MFB-512-8-1-M boards.
• Hardcopy (claims 4, 13–14, 20, 28–29, 37, 46–47): photographic printers either downstream of the displays (via slave monitors) or fed by direct optical output from the cameras.
• Objective selection (claims 5, 15–16, 21, 30–31, 38, 48–49): multiple selectable objectives, each built as a negative-diopter lens with a superimposed positive-diopter lens spaced at a predetermined distance so no refocusing is needed after a lens change (the rotary turret of FIGS. 5A/5B).
• Lithography lens (claims 6, 10, 22, 25, 35, 42): the objective may be a lithography lens.

Literal-text discrepancies I am not auto-correcting

1. Parent application number. The US 4,651,200 text (Google Patents) states the CIP parent is "U.S. Ser. No. 697,930," while the reissue document as returned by search states "U.S. Ser. No. 697,730." I am reporting both as found rather than reconciling them; the family listing associates US 4,673,973 with application 06/697,930.
2. Reissue scope change. The RE34,622 text shows the "bending" / "direct it toward" language struck out of independent claims 1 and 7 (shown as ~~bending~~), meaning the reissue broadened those claims to no longer require the prism/bending element. Two separate reissues appear in this family: RE34,622 (from application 07/324,779, 1989) and RE33,883 (granted 1992-04-14, titled "Split-image multi-power microscopic image display system and method").

Uncertainty statement

• I have no authoritative confirmation of any litigation or Federal Circuit proceeding involving US 4,651,200, and specifically none in 2026. Given that Google Patents records the patent as "Ceased" with anticipated expiration 2005-02-04, a 2026 CAFC appeal on its merits would be atypical (past-damages appeals are possible, but I found none).
• Assignee/inventor addresses and the "corp of New York" designation come from the assignment record as reproduced in the patent front-matter; I did not independently verify current ownership.
• If you need a definitive docket check, the authoritative sources are USPTO Patent Center / Patent Public Search for the application, and the CAFC CM/ECF docket system or PACER — neither of which I was able to query directly here.

I'll research litigation involving US Patent 4651200 across patent litigation databases.

The first search returned an irrelevant trademark registration (No. 946,120), not our patent. Let me search more targeted litigation sources.

Let me query litigation-specific databases directly.

Summary: No litigation found for US Patent 4651200

I was unable to identify any litigation — district court, CAFC, ITC, or PTAB — involving US Patent 4,651,200 specifically. I found no case in which this patent number appears as an asserted patent, and I am not going to invent a docket number, court, or outcome to fill that gap.

What I searched

• Google Patents page for US4651200 (including its "Cited By," "Similar Documents," and family/legal-events sections) — no litigation tab or litigation entries are present; only patent citations and related-family members.
• Targeted queries for "4651200" / "4,651,200" combined with litigation, infringement, lawsuit, and complaint.
• Litigation-portal content (Unified Patents portal case lists) and court-document repositories surfaced in results.

The searches returned only false positives that must not be conflated with this patent:

• A TTAB trademark cancellation (Poly-America v. Illinois Tool Works) concerning Trademark Registration No. 946,120 — a trademark, not US 4,651,200.
• Various unrelated patent suits (Versata/Ford, Stratasys/Bambu, Celonis/SAP, Illumina/Affymetrix, Unified Patents PTAB matters). None assert US 4,651,200.

Why the absence is plausible (not proof of absence)

• The patent is recorded as Ceased, with anticipated expiration 2005-02-04, and its term began from a 1985-02-04 priority date. Any enforcement window is long closed.
• The patent was reissued as US RE34,622 (reissue application filed 1989-03-16; reissue granted 1994-05-31). Reissue family members (RE34,622 and the sibling RE33,883 in the "Similar Documents" list) are the more likely vehicles for any assertion, though I found no litigation for those either in these searches.
• The assignee, National Biomedical Research Foundation (a nonprofit research foundation), does not appear in the litigation records I retrieved as an active patent plaintiff.
• Coverage caveat: pre-1990 district court filings and older PATSTAT/Docket Navigator-era records are unevenly indexed, and PACER does not provide free full-text search of historical complaints. So a 1987–1995 enforcement action could exist without surfacing in the sources I could reach. I could not confirm one.

Key patent facts (for the record, per source)

Bottom line

No litigation involving US 4,651,200 was identified. If you need a negative-confirmation suitable for a clearance or due-diligence memo, the next steps would be a paid Docket Navigator / LexisNexis Patent Litigation search on 4,651,200, RE34,622, and RE33,883, plus a manual PACER name search for "National Biomedical Research Foundation" and "Ledley" as plaintiffs — none of which I can run from the tools available here. I'd flag this explicitly as "not found in searched sources," not as "confirmed never litigated."

I'll verify the canonical (empty) list against what's publicly searchable before writing up.

Proceedings overview

There are zero AIA trial proceedings on file for US 4,651,200 — no IPRs, no PGRs, and no CBM reviews, in any status (active, instituted, settled, or denied) — so the breakdown by status is 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution denials, and the defensive posture is not "this patent has been hardened through PTAB"; it is the rarer and much simpler posture that the patent has been expired since 2005-02-04 and was never tested at the PTAB because the AIA trial regime post-dates its entire enforceable life.

---

Proceedings (none on file)

No proceedings to enumerate

• Canonical source. The structured "PTAB proceedings on file" block supplied with this task — sourced from the USPTO Open Data Portal API — returns no AIA trial proceedings for US 4,651,200. Per the operating instructions, that block is the canonical list, and I found nothing to displace it.
• Independent verification attempts (negative). I searched for the patent number alone and in combination with "IPR," "PTAB," "AIA trial," the assignee ("National Biomedical Research Foundation"), and the inventor ("Robert S. Ledley"), and for its reissue numbers (RE34,622 / RE33,883). Results returned only the patent documents themselves, unrelated litigations involving other patents (e.g., a Silicon Graphics v. ATI Markman opinion referencing a different '200 patent containing a "host processor" limitation — not this patent), and unrelated IPR petitions. No petition, institution decision, Final Written Decision, or CAFC appeal for US 4,651,200 surfaced in any search.
• Because no proceeding exists, I cannot report — and will not fabricate — a proceeding number, petitioner, judge panel, institution date, grounds, claim-level disposition, or appeal docket. Every such field would be invention.
• Why the absence is expected rather than probative. AIA trials became available on 2012-09-16. This patent's priority date is 1985-02-04 and its anticipated expiration is 2005-02-04 — more than seven years before the first IPR could be filed. A CBM review was likewise unavailable (CBM was limited to financial products/services; a microscope imaging system would not qualify). So the null PTAB record here does not carry the usual signal ("no one bothered to challenge it"), because for most of the relevant period there was no forum to do so and no live term to defend.

Adjacent non-AIA post-issuance events (context, not AIA trials)

These are not PTAB proceedings, but they are the only post-issuance adjudicative history this patent has, and a defendant will want them on the list:

Two defensive observations a defendant should put to work immediately (both are hypotheses to verify against the file history, not conclusions I can certify from the front-matter data alone):

1. § 251(d) two-year window. A reissue that broadens the claims must be applied for within two years of the original grant. The '200 patent granted 1987-03-17; the reissue application is recorded as filed 1989-03-16 — by my arithmetic, one day inside the window. If any part of the reissue broadening was effected or perfected after 1989-03-17, or if the 1989-03-16 date is not the operative § 251 filing date, the broadened claims would be invalid under § 251(d). This is a cheap, high-leverage check.
2. Recapture. If the "bending"/prism limitation was added during original prosecution over the cited dual-magnification art (e.g., US 3,451,464 Optical dual magnification system; US 3,488,104 Dual focal plane microscope; US 3,895,854 Chromatic method and apparatus for conducting microscopic examinations at a plurality of magnifications), deleting it in reissue is classic impermissible recapture under § 251.

---

Strategic summary

Claim status: CANCELED vs. SUSTAINED vs. UNTESTED. No claim of US 4,651,200 was ever canceled, narrowed by estoppel, or held unpatentable in any AIA trial — there were no trials. But "all claims sustained" would be a misleading way to say it. The original 49-claim set was surrendered and substituted by the RE34,622 claims on 1994-05-31; the reissue claim set is the only claim set that defined the patent right for the last decade of its life. Original independent claims 1 and 7 were broadened in reissue (bending/prism element struck); the remaining independent claims (17/23, the "underscanning" pair, and 32/39, the "two-magnifying-paths / Barlow lens" pair) appear unchanged in substance. Today, all 49 original claims and all reissue claims are UNTESTED at the PTAB and EXPIRED as a matter of term. For a defendant, the practical taxonomy is not canceled/sustained — it is expired.

Estoppel landscape. Because no IPR/PGR/CBM petition was ever filed, no § 315(e)(2) estoppel exists against anyone. There is no petitioner whose grounds are locked out, no real-party-in-interest or privity chain to trace, and no defensive-aggregator trail (no Unified Patents, RPX, or similar involvement is visible in any record I could find). The entire prior-art field — including all 20 references cited on the face of the patent plus everything the examiner never saw — remains formally available to any defendant. The two real gates are instead: (a) § 286's six-year damages look-back, which for a patent that expired 2005-02-04 means any pre-expiration recovery is long time-barred absent tolling or a government-defendant scenario (see 28 U.S.C. § 1498), and (b) § 252 intervening rights (absolute and equitable), which protect a defendant against liability on the broadened reissue claims for activity commenced before the reissue grant.

Pattern signals. There is no pattern to read: one inventor (Ledley), one institutional assignee (National Biomedical Research Foundation), one CIP family (US 4,673,973 → '200 → US 4,769,698, plus EP 0209591 / WO 1986/004758 / CA 1,295,863), and two reissues. The patent owner never litigated the patent to a PTAB appeal, and no party ever petitioned against it. The family's commercial footprint is a 1987 New York Times note about "the double-power lens" — an era of patenting, not assertion.

---

Recommended next steps

If you are a defendant and the demand letter cites US 4,651,200:

1. Demand the claim chart be run against the live claim set, not the printed patent. The enforceable claims after 1994-05-31 are the RE34,622 claims. Link and quote the reissue disposition directly: US RE34,622 on Google Patents and the amended claim text at FreePatentsOnline RE34622 (independent claim 1 as amended reads: "providing the second optical output to a second camera which produces a second video output characterized by the first magnification" — with bending and direct it toward struck). Any infringement theory built on the un-amended original "bending/prism" language is directed at surrendered text.
2. Run the term/limitations calendar first. Anticipated expiration 2005-02-04; § 286 six-year look-back; § 252 intervening rights. If the accused conduct is post-2005-02-04, the patent is facially incapable of being infringed. If the letter asserts the original claims rather than the reissue claims, ask for the § 252 basis.
3. Order the 07/324,779 reissue file history (USPTO Patent Center, application 07/324,779, filed 1989-03-16) and check (i) the § 251(d) filing date against the 1987-03-17 grant, and (ii) whether the deleted "bending" limitation was added during original prosecution over US 3,451,464 / US 3,488,104 / US 3,895,854. Either finding is a validity defense to the broadened reissue claims.
4. Confirm the RE33,883 relationship. If RE33,883 is a reissue of the parent US 4,673,973 rather than of the '200 patent, that matters for which claim set a demand letter could ever invoke. I could not establish this from the retrieved data — verify before relying on it.
5. PTAB is a dead end here and should not be budgeted. There are no proceedings to join, no estoppel to exploit, and — critically — an expired patent cannot be challenged in an IPR for prospective relief; the only reason to file would be to knock out a past-damages claim, and the damages window appears closed. Spend the money on the priority/term defenses and the reissue file history instead.

If you are the patent owner: the honest answer is that there is no PTAB posture to report. The patent's record is an empty set, and the term expired 2005-02-04. Assertions resting on this patent are vulnerable on term alone, independent of any validity question.

Verification sources used (all returned nothing for this patent): USPTO PTAB E2E, PTAB API / decisions, CourtListener, Google Patents US4651200A.

Confidence statement. High confidence that no AIA trial proceeding exists — the canonical ODP list is empty and independent searches corroborate it. Lower confidence (and explicitly flagged rather than asserted) on: the parenthetical details of the RE33,883 reissue; the full text of the RE34,622 dependent claims 2 and 9, which returned truncated ("wherein one of the …"); and the § 251(d)/recapture analysis, which is arithmetic and inference from front-matter data and must be confirmed against the actual file history.

I'll research the assignment record for this patent, starting with the bibliographic data already in the patent text and then checking external sources.

Assignment & Ownership Reconstruction — US 4,651,200

Sourcing caveat (read first): I was cut off before completing live queries against the USPTO Assignment Center (https://assignmentcenter.uspto.gov/) and its indexed mirror (https://assignment.uspto.gov/patent/index.html). The assignment data below is drawn from the Google Patents legal-events record reproduced in the authoritative patent text (which mirrors the same underlying USPTO reel/frame records) plus the public sources I did retrieve. One field the task specifically asks for — the correspondent of record — was not exposed in the data I could pull, and I am not going to invent it. That gap is flagged in place.

---

Inventors

Unusual-pattern check — no departure pattern. The "all inventors leave within 12 months of filing" precursor is not present. Ledley founded NBRF in 1960 and remained its head for ~50 years, retiring in 2010 and dying 2012-07-24. This is the opposite of a fire-sale precursor: inventor and assignee are the same controlling person for the life of the organization. (Confirms: NBRF "chartered in 1960"; "Ledley would lead the NBRF until his retirement in 2010." Source: Wikiwand/Wikipedia Robert Ledley.)

Related-inventor note: NBRF's later filings are in the name of Fred D. Ledley (e.g., US 8,483,966; US 8,438,042; and 2017/2019 published applications), i.e., a family-adjacent inventor — useful for tracing the NBRF entity's continued existence, but not relevant to inventorship of this patent.

---

Original assignee

National Biomedical Research Foundation, 3900 Reservoir Road N.W., Washington, D.C. 20007, "a corp. of New York" (per the issued patent front-matter and the 1985-12-16 assignment record).

• Line of business: Nonprofit biomedical/computer research organization founded 1960 by Robert S. Ledley. Its mission was to spur computer use in biomedical research. It published journals (e.g., Pattern Recognition) and operated the Protein Identification Resource (PIR) protein-sequence database; revenue sources by ~1980 included federal/university/corporate support plus "publication of journals and the sale of electronic instruments, software, and patents."
• Did it ship a product embodying these claims? No evidence. NBRF's commercially notable hardware was the ACTA whole-body CT scanner (1970s), commercialized through a spun-off corporation, Digital Information Science Corporation (DISCO/Digital), not a product of the split-image microscope display system of US 4,651,200. I found no commercialization of the claimed dual-path microscope/TV apparatus. Treat "no product for this patent" as an evidence-based negative, not proof of non-practice.
• Current status: Appears to still exist as an entity.
  • It continued to file patents/trademarks into at least 2019 (uspto.report entity page for National Biomedical Research Foundation).
  • Ledley retired from NBRF in 2010 and died 2012-07-24 (NYT obituary, 2012-07-25).
  • No bankruptcy, dissolution, or Chapter 7/11 filing found for NBRF.

Related-entity aside (not an assignment of this patent): the NBRF's 1970s scanner business, Digital/DISCO, was liquidated and its assets distributed to a residual entity (per Rotolo v. Comm'r, T.C.). That liquidation is about the pre-patent CT-scanner business, predates US 4,651,200, and did not convey this patent. Do not read it as a fire-sale of this patent.

---

Assignment timeline

The patent text's legal-events record shows exactly one recorded assignment in the chain, plus post-issuance reissue activity (same owner — not assignments).

• 1985-12-02 (executed) / recorded 1985-12-16 — Reel 004488 / 0138

  • Conveyance: Assignment ("ASSIGNMENT OF ASSIGNORS INTEREST")
  • Assignor: Robert S. Ledley
  • Assignee: National Biomedical Research Foundation, 3900 Reservoir Road N.W., Washington, D.C. 20007, a corp. of New York
  • Correspondent: Not retrievable from the sources available to me. The Google Patents legal-events record reproduces the reel/frame and the assignor/assignee but not the recording correspondent's name, firm, or address. Per the task's own instruction, I am not fabricating it; this field requires a direct USPTO Assignment Center lookup to confirm.
  • Context: Original inventor-to-employer assignment (standard capture of employee/inventor rights by the operating nonprofit assignee). Not a sale, not an NPE transfer.

• Post-issuance reissue — no new assignee. Application 07/324,779 filed 1989-03-16; granted as US RE34,622 (issue date 1994-05-31). Reissue is a re-grant to the same owner and does not appear as a conveyance.

• A certificate of correction was recorded 1987-08-18 (administrative, not a transfer).

Family reissue cross-reference (flagging a discrepancy, per instructions): The earlier generated summary noted two reissues in this family — RE34,622 and RE33,883 (granted 1992-04-14). The Google Patents "Related Child Applications" list for US 4,651,200 shows only US 07/324,779 → US RE34,622, which is the reissue of this patent. RE33,883 carries the identical title ("Split-image multi-power microscopic image display system and method") and is associated in NBRF listings with application 07/367,300. On the evidence available, RE33,883 appears to be the reissue of a sibling "split-image" patent (most plausibly the CIP parent US 4,673,973 or another NBRF member of the family) rather than of US 4,651,200 itself — but I could not conclusively resolve which underlying patent each reissue number belongs to, so I am reporting the uncertainty rather than reconciling it. Neither reissue changes ownership.

Conclusion of the transfer search: After the single 1985 assignment, no further recorded assignment was found — no LLC formation, no sale, no security interest, no merger, no license record. The chain terminates where it started: NBRF was still the owner at the last recorded event, and the patent is recorded as Ceased, with anticipated expiration 2005-02-04.

---

Timeline diagram

timeline
    title Ownership of US 4651200
    1985 : Application filed 4 October
         : Ledley assigns rights to NBRF
    1987 : Patent issued 17 March
    1989 : Reissue application filed
    1992 : Reissue RE33883 granted
    1994 : Reissue RE34622 granted
    2005 : Patent term expires
    2010 : Inventor retires from NBRF
    2012 : Inventor Ledley dies

---

NPE / troll-pattern signals

---

Verdict

Insufficient data — per the rubric's own definition ("no records, or only the original assignment").

Justification: The record contains only the original assignment — Ledley → National Biomedical Research Foundation, executed 1985-12-02, recorded 1985-12-16, Reel 004488/0138 — with no subsequent recorded conveyance of any kind. Because no post-issuance transfer exists, there is nothing to score against the shell-entity, known-asserter, cascading-transfer, pre-litigation, privateering, or defensive-aggregator tests, so the chain yields no NPE evidence either way. Substantively, every affirmative NPE signal is absent: the patent stayed with its original nonprofit research assignee (NBRF) from 1985 until it ceased, and it expired 2005-02-04 — meaning it was long off-term before any modern assertion campaign could exist. This is best characterized as an original-assignee / non-asserting situation, but under the forced-choice rubric the correct label is Insufficient data.

Two items to close the record with a direct lookup (which I could not run):

1. The correspondent of record on Reel 004488/0138 (needed to formally clear signal #3).
2. Confirmation there are no post-1985 recordings (security agreements, name changes, or later sales of the NBRF portfolio) that Google Patents' legal-events feed may not surface.

Verify at the USPTO Assignment Center:
https://assignmentcenter.uspto.gov/ (search by patent number 4651200), mirror: https://assignment.uspto.gov/patent/index.html.

Caveat carried forward from the prior section: I found no litigation and no 2026 CAFC docket naming this patent; that docket search is negative/incomplete, not affirmative proof of absence. Given the "Ceased" status and 2005 expiration, a 2026 merits appeal would be atypical.

I'll verify US 4,651,200 in the USPTO record and pull details on each cited reference. Running targeted searches now.

Prior-Art Analysis — US 4,651,200

Source-verification note (read first). My searches returned the authoritative text of US 4,651,200 and its reissue (US RE34,622) via Google Patents/patentimages, plus Justia and FreePatentsOnline mirrors. I was not able to run a query directly against USPTO Patent Public Search/Patent Center in this session, so the "USPTO database" portion of your request is satisfied indirectly through those records rather than by a native USPTO screen. Where the record and the printed patent disagree, I flag it and do not auto-correct.

Scope note. US 4,651,200 is a 1985-10-04 CIP (priority 1985-02-04) and is pre-AIA, so the cited art is §102(a)/(b)/(e) art. Critically, the independent claims (1, 7, 17, 23, 32, 39) all require a camera producing a video output and display means processing that video output. That single limitation defeats single-reference §102 anticipation for every reference on the examiner's list, because none of the 20 references discloses a split-path microscope feeding two TV cameras whose video outputs are processed to two displays. Accordingly, the cited art functions mainly as §103 material, with a handful of references being plausible §102 art against narrow dependent claims. I say this explicitly rather than manufacturing anticipations.

---

The 20 references cited on the face of US 4,651,200

---

Which claims are actually at risk

No cited reference anticipates any independent claim (1, 7, 17, 23, 32, 39). Every one of those claims requires, in combination: (a) a beam split off a single objective's output, (b) two optical paths, (c) two cameras each producing a video output at a different magnification, and (d) display means processing both video outputs to show two images. No single cited reference teaches (c)+(d). References 8, 9, and 19 cover parts of (a)–(b); references 12/16 cover fragmented parts of (c); together they are §103 material, not §102 art.

Dependent claims where §102 is genuinely arguable (subject to element-by-element verification against the full reference texts, which I could not retrieve in full here):

• Claims 3, 11–12, 19, 26–27, 36, 44–45 (data overlay) ← reference 18 (US 4,245,252, Sony character-display TV camera), buttressed by US 4,245,252's teaching of superimposing display data on camera video.
• Claims 17 and 23 (reduced-scanning / underscanning magnification) ← reference 16 (US 4,199,785, Honeywell electronic zoom), if its raster control maps onto the claimed "reduced-scanning mode."
• Claims 33 and 41 (Barlow lens) ← reference 13 (US 3,871,741, Clave), which expressly claims a Barlow amplifier inserted to raise magnification without refocusing. This is the cleanest single-reference hit in the set, though it is not a split-path system.
• Claims 5, 15–16, 21, 30–31, 38, 48–49 (selectable objectives; negative-diopter + superimposed positive-diopter, no refocusing) ← references 13 (Clave, "without refocussing") and 5–7 (Bausch & Lomb variable-power/zoom), but none shows the specific negative+positive diopter pair, so these are §103 rather than §102 challenges.
• Claims 2, 9, 18, 24, 34, 43 (prism bending) — the cited art is replete with bending prisms (e.g., refs. 8, 9, 19 use deflecting prisms/mirrors), so the prism sub-limitation adds little; the question is whether it is at the end of the second path adjacent the second camera as claimed.

---

Things you must not misread

1. Forward citations are not prior art. The "Cited By" list (Intel US 4,680,635; Bally US 4,864,410; View Engineering US 4,872,052; Abbate US 2004/0001145; Soler US 2007/0064143; etc.) and the "Families Citing this family" list are later documents and cannot be §102 art against US 4,651,200. Likewise the related applications US 4,673,973 (CIP parent, 1987-06-16) and US 4,769,698 (CIP child, 1988-09-06) are same-family/same-inventor documents, not prior art.
2. Two reissues exist, and the reissue broadened the independent claims by striking the "bending"/"direct it toward" language from claims 1 and 7 (see RE34,622), converting the prism limitation into a nominal "further inverting" dependent claim (RE34,622 claim 18 / claim 24). Any anticipation analysis keyed to the issued US 4,651,200 wording changes if you analyze the reissue claims instead — the reissue claims are broader, so the §102 analysis above is more favorable to an anticipator under RE34,622 than under the original.
3. Literal-text discrepancies I am not reconciling (per the no-auto-correct rule):
   • The US 4,651,200 specification (Google Patents) recites the CIP parent as "U.S. Ser. No. 697,930"; the RE34,622 document as returned by search recites "U.S. Ser. No. 697,730 … now U.S. Pat. No. 4,673,973." Both strings are reported verbatim.
   • The patent's own "generally pertinent" list names 13 patents (2,527,719; 2,699,092; 2,950,649; 3,030,861; 3,057,259; 3,353,891; 3,459,464; 3,488,104; 3,503,684; 3,871,741; 3,895,854; 4,218,112; 4,440,475), whereas the front-page examiner citation list contains 20, adding 2,685,820; 3,525,803; 3,835,246; 3,883,689; 4,199,785; 4,245,252; 4,546,771. Also note that two different reissues appear in the family: RE34,622 (from 07/324,779, 1989) and RE33,883 (1992-04-14). I have not assumed one is an error for the other.

Bottom line: the examiner's 20 references are dominated by variable-magnification/zoom optics and dual-view microscopes. Only US 3,459,464 (Vickers), US 3,488,104 (Fairchild), US 4,440,475 (CAMECA), US 3,871,741 (Clave), US 4,199,785 (Honeywell), and US 4,245,252 (Sony) rise to "material," and each maps to a different feature (dual magnification / beam splitting / dual-magnification switching / no-refocus magnification change / electronic zoom / on-video character overlay). The patent's novelty resides in the combination — simultaneous split-path, dual-magnification, dual-camera, dual-monitor display — which is why this set reads as an obviousness (over the combination) rather than an anticipation set.

I'll ground the obviousness analysis in the actual prior-art references cited on the face of US 4,651,200. Let me pull details on the most relevant ones.

Now the electronics/photometer-side references.

Obviousness analysis — US 4,651,200 under 35 U.S.C. § 103

Builds on the earlier Summary and Litigation sections (I do not repeat the claim architecture, family, or reissue findings). Two things established there carry directly into this analysis and are not restated: (a) independent claims 1/7, 17/23 and 32/39 map onto the second, third and fourth embodiments respectively — no independent claim covers the "most preferable" first (demagnifying) embodiment; and (b) reissue RE34,622 struck the "bending / direct it toward" language from claims 1 and 7.

---

1. Framework and evidentiary caveats

Legal standard applied: pre-AIA § 103 as construed in KSR Int'l v. Teleflex — the claimed subject matter is obvious if the differences over the prior art are such that the subject matter as a whole would have been obvious to a PHOSITA at the time the invention was made, and the analysis must consider (i) scope/content of the prior art, (ii) differences, (iii) level of ordinary skill, and (iv) secondary considerations. Because the claimed subject matter is a combination of old elements each performing its own known function (optics + video cameras + monitors + printers + turret), the controlling rationale is KSR's "predictable variation" / "known technique to improve similar devices in the same way" line of reasoning, and the combination produces no more than the predictable sum of its parts.

PHOSITA (as of Feb. 1985): a microscope/video-microscopy designer with a BS in optics or EE plus ~2–4 years' experience in microscope optics and CCTV microscopy; routinely capable of designing relay/demagnifying lens trains, selecting beam splitters and folding prisms, and adjusting raster scan timing in a vidicon or other camera tube. This is a mature, crowded art — the classic KSR / In re Kahn situation.

Prior-art dates. All references discussed below issued between 1950 and 1985. US 3,459,464 (1969), US 3,488,104 (1970), US 3,895,854 (1975), US 3,871,741 (1975), US 4,199,785 (1980) and US 4,245,252 (1981) all comfortably pre-date the 1985-02-04 priority date and are § 102(a)/(b) art. Two care points: US 4,440,475 issued 1984-04-03 and US 4,546,771 issued 1985-10-15 (after the filing date), so the latter is available at most as pre-AIA § 102(e) art on the strength of its 1982-03-04 filing date — I would not lead with it.

Evidentiary caveat (important). I could not retrieve the actual examiner's § 103 rejections or the file wrapper for application 06/784,615, nor the reissue prosecution. What follows is my independent reconstruction from the reference disclosures. I retrieved full or substantial text for US 3,459,464, US 3,488,104, US 3,895,854 and US 3,871,741, and the key passage of US 4,199,785. For US 4,245,252, US 4,218,112, US 3,030,861, US 3,057,259 and US 4,440,475 I am working from the titles/abstracts on the patent's front page and flag them as unverified in full text. Note also that the cited US 3,648,602 (Clave) appears in the text of US 3,871,741 but is not itself of record in US 4,651,200.

Source for the authoritative patent text: https://patents.google.com/patent/US4651200/en

---

2. The prior-art set on the face of the patent, and what each actually teaches

Patentee admissions usable against the claims. The Background recites that switching magnification and refocusing wastes "much time" and is "inefficient and inconvenient"; and the specification treats the multi-position lens turret as known ("In the prior art, it is well-known to provide a lens switching arrangement wherein lenses of differing magnification may be rotated into position"), the microcomputer boards, the mixers, the tricorder head (Olympus), and the printer (47th Street Photo Speed Printer) as off-the-shelf items. These are admissions that the non-optical elements are conventional apparatus elements. This is precisely the posture in which § 103 combination analysis is most favorable to a rejection.

---

3. Element mapping — independent claim 32 (the most vulnerable claim)

Claim 32 (low-power objective → magnify both paths) is the closest to being met by a single reference plus a trivial substitution:

The only genuine differences are (1) eyepieces vs. the claimed "magnifying means" and (2) giving each path its own camera/monitor rather than routing by wavelength to one sensor — a difference the reference itself suggests. The remaining step is to substitute a Barlow/diverging magnifier for an eyepiece and to duplicate the camera-monitor pair, i.e., a predictable variation using known elements, each performing its known function, with no change in the principle of operation.

---

4. The combinations I would assert, with motivation

Combination A — Claims 1, 2, 7, 8, 9 (and their dependents)

Primary: US 3,895,854 (Coulter). Secondaries: US 3,488,104 (Fairchild) and US 3,459,464 (Vickers).

• Motivation to combine: All three are in the same field (optical microscopy, two outputs from one objective) and address the same problem the patent itself identifies — obtaining more than one magnification from a single specimen without interrupting or re-establishing the view (US 3,459,464: no "temporary interruption"; US 3,895,854: alternative magnifications from one objective; US 3,488,104: two paths from one beam divider). KSR holds that a known technique used to improve one device, where a PHOSITA would recognize it would improve similar devices the same way, is obvious.
• What the secondaries supply: the beam-divider cube with a differential path containing an optical element (3,488,104) and the beam-deflecting means establishing two paths from one magnifying combination (3,459,464) — covering the "splitting means" and "bending… toward a second camera" limitations. The art's own folding hardware (45° mirror 38 in 3,895,854; pentapriston 49 in 3,488,104) makes prism-bending routine.
• Reasonable expectation of success: high. Each path behaves exactly as it would alone; two cameras fed by one splitter each display what a single camera would have displayed. No unpredictable interaction.
• Note on the "no-optics" second path of the second embodiment: this is the trivial deletion of the eyepiece that 3,895,854 shows in that path — a change in degree, not in kind.

Combination B — Claims 17, 18, 23, 24 (underscanning)

Primary: US 4,199,785 (Honeywell). Secondary: US 3,895,854 or US 3,488,104.

• US 4,199,785 discloses exactly the claimed technique: magnifying by adjusting the horizontal scan voltage and vertical sweep so a fixed line count covers a smaller area, with resolution loss acknowledged and accepted. The numerical 0.4472 factors in the patent are simple consequences of √(1/5) — arithmetic, not invention.
• Motivation — and note this cuts strongly against the patentee: the specification itself argues that the preferred embodiment is preferred because fewer optical elements should be in the high-power path ("each optical element added to an optical path introduces some degree of degradation"; the first embodiment is "most preferable since … optical elements are introduced into the low-power path"). That is the patentee's own articulated reason to substitute electronic magnification for an added optic in the high-magnification path — i.e., the motivation for Combination B is supplied by the specification's own design rationale.
• Reasonable expectation of success: high; US 4,199,785 shows the technique works and characterizes the resolution trade-off as tolerable.

Combination C — Claims 32, 33, 34, 39, 40, 41, 43 (Barlow/magnify both paths)

Primary: US 3,895,854. Secondary: US 3,871,741 (Clave).

• Motivation: Two-lens magnifiers of the eyepiece/Barlow type are the standard way to raise microscope magnification, and US 3,871,741 expressly uses a Barlow amplifier to increase magnification "instantaneously … without refocussing," with path-length compensation. The patent itself calls element 184 a "magnifying lens or Barlow lens" — i.e., names a known commercial microscope accessory (Barlow lenses/teleconverters). Substituting one for the other is within the skill level and is a KSR "known technique" combination.
• Anticipated counterargument and rebuttal: 3,488,104 goes to some effort to equalize magnification across its two paths (correction means 30). That is not a teaching away: 3,488,104 equalizes because its purpose is overlaying a mask image on a wafer image at one eyepiece; it simultaneously teaches that magnification in a split path is a designable parameter set by the length and power of that path (lensed mirror face 48). 3,895,854 supplies the opposite, deliberate teaching of distinct magnifications in distinct paths.

Combination D — Claims 3, 6, 11, 12, 19, 26, 27, 36, 44, 45 (data overlay; lithography lens)

Overlay: US 4,245,252 (Sony, TV camera having a character display) + the primary of A/B/C.

• Motivation: specimen identification on the displayed image and on the eventual record — the cytology/chromosome screening context (US 3,503,684; US 3,525,803; the patent's own chromosome example). US 4,245,252 is a TV camera that generates its own character display; mixing that video with camera video through a conventional mixer is a predictable combination of two known video techniques. Caveat: I could not retrieve US 4,245,252's full text, so I cannot confirm the character-generation circuit detail; the title and the examiner's citation of it are my basis.
• Lithography lens (claims 6, 10, 22, 25, 35, 42): Motivation — US 3,488,104 is expressly a semiconductor mask/wafer inspection instrument, and the patent's own text states the rationale ("a lithography lens having a large field"). Choosing a large-field objective for the low-magnification path is a selection among known objective types for its known property.

Combination E — Claims 5, 15, 16, 21, 30, 31, 38, 48, 49 (multi-objective turret; negative + positive diopter pair)

US 3,871,741 + US 3,030,861 / US 3,057,259 (Bausch & Lomb) + the patent's own admission that turrets are known.

• Motivation: the problem is stated in the patent's Background and solved by Clave for the express purpose of avoiding refocusing. The specific structure recited — a negative-diopter lens with a superimposed positive-diopter lens spaced at a predetermined distance — is the textbook afocal (Galilean) pair. By elementary optics, a negative/positive pair separated by the sum of their focal lengths is afocal and therefore does not alter the convergence of the emerging beam, so the image plane does not move; and its angular magnification is the ratio of the two focal lengths. In other words, the claimed "discovery" is a direct mathematical consequence of the afocal condition, and the patent claims it as an apparatus. This is the one group where I rate obviousness as strong but worth verifying against the file history, since the applicant presented it as an inventor discovery.
• Variable-power microscope objectives with interposed lens groups (Bausch & Lomb references; also US 3,353,891's simultaneous NA control) show turret-mounted magnifiers were known; combining them with an afocal pair for focus invariance is the predictable design step.

Combination F — Claims 4, 13, 14, 20, 28, 29, 37, 46, 47 (hardcopy)

Any of the above primaries + a conventional photographic printer (and, alternatively, direct optical take-off from the camera).

• Motivation: durable patient/archival records in a diagnostic workflow; the patent itself identifies the printer as an off-the-shelf device ("47th Street Photo Speed Printer"). Attaching a known printer to a known display (or to a known camera), with each element performing its ordinary function, is the paradigm KSR combination; there is no new cooperativeness and no unexpected result. I could not verify which of the cited references shows a photographic printer specifically, so I would pair this group with US 4,218,112 (scanning/recording photometer microscope, unverified) or rely on the admission that printers were commercial.

---

5. Claim-by-claim disposition (my assessment, not a record-based one)

Cross-cutting point on the "bending" limitation. The patent itself notes the double inversion caused by splitter 18 and prism 32 and re-orients camera 34 and monitor 36 to compensate — an admission that the bending element is a packaging/orientation expedient with a foreseeable image-orientation consequence. Folding mirrors at 45° and pentaprisms (US 3,488,104; US 3,895,854; US 3,459,464) are ubiquitous in this art. The reissue's deletion of "bending / direct it toward" from claims 1 and 7 is consistent with the patentee's own recognition that the bend is not the inventive contribution.

---

6. Counterarguments a patentee would raise, and why I think they fail

1. "Simultaneity." US 3,895,854 describes examining "at one magnification at a time" via filter-wheel selection. Rebuttal: the same specification expressly contemplates separate paths to separate sensors, and simultaneity is achieved by the trivially obvious step of populating both paths with sensors — which the reference's own alternative discloses. Also, the claims do not require simultaneity of display in a way that changes the apparatus.
2. "Teaching away" via US 3,488,104's equalization. Rebutted above: equalization for overlay purposes is not a disparagement of differential magnification in split paths; it teaches magnification as a controllable path parameter.
3. "Unexpected result / superior image quality by keeping optics out of the high-power path." This is a design rationale, not an unexpected result; it is the kind of predictable consequence a PHOSITA would anticipate (optical degradation from added elements was well known — indeed the patent says so). It also cuts for Combination B.
4. Secondary considerations. I found no objective evidence of nonobviousness: no known commercial success with nexus, no licensing, no copying, no long-felt unmet need evidence beyond the specification's own assertion of inconvenience, and (per the earlier Litigation section) no litigation or validity challenge in which such evidence would have been adduced. The 1987 New York Times mention noted in the Summary is a contemporaneous report of the grant, not evidence of nonobviousness. Absent nexus, secondary considerations do not rescue these claims.

---

7. Bottom line

On the face of the references the applicant's own specification lists as "generally pertinent," the independent claims break down as follows: claims 32/39 are the weakest (US 3,895,854 alone supplies the architecture, differing only in eyepiece-vs-Barlow and one-sensor-vs-two — the latter expressly suggested by that reference); claims 1/7 fall to 3,895,854 in view of 3,488,104 and 3,459,464; and claims 17/23 fall to US 4,199,785, with the motivation supplied by the patent's own stated preference for minimizing optics in the high-magnification path. The dependent groups (overlay, hardcopy, turret, lithography lens, prism-bending) each add one conventionally known element performing its known function, and the combination yields nothing beyond the predictable sum of the parts — the KSR fact pattern.

What I could not verify, stated plainly:

• I did not obtain the examiner's actual § 103 rejections or the reissue file wrapper, so I cannot say whether the Patent Office made any of these combinations. My analysis is independent.
• Full texts for US 4,245,252, US 4,218,112, US 3,030,861, US 3,057,259, US 4,440,475, US 2,527,719 were not retrieved within my tool budget; those points rest on front-page titles/abstracts and are flagged above.
• My tool budget was exhausted before I could check the prosecution history, so I do not know which reference(s) the examiner applied, or whether any reference of record was distinguished on the record. If a formal validity opinion is needed, the next step is the application 06/784,615 and reissue 07/324,779 file wrappers via USPTO Patent Public Search / Patent Center, and the RE34,622 reissue prosecution (which will reveal why the "bending" language was struck).