US 10502585

I'll search for authoritative information on this patent number, including any litigation/docket references.

US Patent 10,502,585 — Summary

Note on scope: I was able to verify bibliographic and claim data against the authoritative Google Patents record for US10502585B2 and cross-checked against Justia, Patents-Review, and Patents Encyclopedia. However, my searches of CAFC 2026 dockets returned no results connecting patent 10,502,585 (or its application 14/522,462) to any Federal Circuit appeal. I therefore cannot confirm, and do not claim, that this patent has been the subject of any 2026 CAFC docket activity. Treat that as an explicit uncertainty rather than a negative finding.

Abstract

A method comprises supplying an optical input to an interferometric fiber optic gyro (IFOG) at a first frequency and then a different second frequency; detecting a difference in responses of the IFOG to the optical input at the first and second frequencies; and computing a gyro rate as a function of the difference and a correction term.

Plain-Language Overview of the Independent Claims

Claim 1 — Method of operating an IFOG (multi-frequency, self-correcting).
Supply light to the fiber gyro at a first frequency, then at a second, different frequency. At each frequency, detect the phase variation between the counter-propagating optical signals, then take the difference between the two measured phase variations. From that difference plus a correction term, determine the rotation rate (gyro rate) of the IFOG. In plain terms: measure the gyro twice at two different light frequencies, subtract one reading from the other, and use a stored correction value to back out the true rate — without needing to know (recalibrate) the current absolute scale factor.

Claim 7 — System (the same idea in hardware form).
An IFOG plus a fiber-optic light source that can emit at a first frequency and then a different second frequency; a photodetector that measures the phase variation of the counter-propagating beams at each frequency; and a processor that computes the rotation rate from the difference of the two phase variations and a correction term. This mirrors claim 1 as an apparatus/system claim.

Claim 13 — Method of determining the gyro's own correction term (calibration method).
Apply a known (reference) rate to the IFOG and establish the scale factors for inputs at the first and second frequencies. Then run the gyro at the first frequency and record the first phase variation, switch to the second frequency and record the second phase variation. Using the difference between those two measured variations, together with the known applied rate and the two scale factors, derive the IFOG correction term — where that correction term represents the sum of time-dependent errors in the two measurements. In plain terms: this is the factory/bench procedure for "learning" the correction constant that claims 1 and 7 later rely on.

Dependent-Claim Themes (brief)

• Correction-term meaning (2, 8): it represents the sum of time-dependent errors in the two IFOG responses.
• No calibrated scale factor (3, 9): the gyro rate is expressly not computed as a function of a calibrated (live) scale factor — the key alleged advantage over conventional IFOGs, which require recalibration as bias/scale factor drift.
• Pre-computed correction (4, 10): the correction term derives from initial/original scale factors at the two frequencies (e.g., computed at the factory before service).
• Tolerance to drift and to coil darkening (5, 11): the rate computation can keep repeating without recalibrating both scale factors so long as time-dependent errors or a degrading event cause both scale factors to shift roughly equally.
• Governing equation (6, 12, 14): Ω = ((Δn₁/Δt) − (Δn₂/Δt) − C) / (1/SF₁ − 1/SF₂), where SF₁ and SF₂ are predetermined scale factors for the two frequencies and C is the correction term. (Note: in the printed claims, the "Δn₂Δt" term appears with a missing division slash in the OCR/HTML text — a typographical artifact.)

Technical Core

The patent builds on the IEEE Std 952-1997 IFOG model s₀·(Δn/Δt) = (I+E+D)·s₀ₑᵣ and recasts each frequency's response as (Δn/Δt) = Ω + Df, so that subtracting the two responses cancels the common-rate term and leaves the difference of the time-dependent error terms, Df₁ + Df₂ = C. Because that correction term is stable as long as the two scale factors shift together, the gyro can be operated without periodic recalibration — the stated advantage over conventional IFOGs, where drift, fiber degradation, or coil "darkening" would force a scale-factor recalibration.

Related Family

A later Boeing continuation/related filing (US 10,466,067 B2, 2019-11-05, "System and method for gyro rate computation for a Coriolis Vibrating Gyroscope") applies analogous two-frequency/self-correcting reasoning to a CVG.

Uncertainty statement: All patent bibliographic, claim, and description content above is grounded in the authoritative patent record and is high-confidence. The stated absence of CAFC 2026 docket activity for this patent is based on searches that returned no matching results; it is not a definitive confirmation that no such proceeding exists, and the search was capped before exhaustive docket-level verification. Anyone needing a litigation-clear answer should confirm directly against PACER/CourtListener and the Federal Circuit docket with the patent number and application number 14/522,462.

I'll search for litigation involving US patent 10502585.

Let me try more specific litigation databases.

Let me search more targeted litigation resources.

Results of Search for Litigation Involving U.S. Patent No. 10,502,585

I found no known litigation involving U.S. Patent No. 10,502,585.

Searches of patent-litigation aggregators and court-document sources (including the Unified Patents litigation portal, Justia/CourtListener dockets, and Federal Circuit materials) returned no case, complaint, docket entry, PTAB proceeding, or CAFC appeal in which U.S. Patent No. 10,502,585 is asserted, challenged, or otherwise at issue.

Critically, the queries returned several similar-but-different patent numbers that must NOT be confused with the patent at issue. Per the strict rule, I flag these as distinct and not responsive:

Summary table

Important caveats and context

1. The patent itself is a Boeing patent. Per the authoritative full text, U.S. Patent No. 10,502,585 B2 ("Gyro rate computation for an interferometric fiber optic gyro") issued 2019-12-10 to inventors Shaun M. Detloff and James K. Gingrich, assigned to The Boeing Company. Google Patents lists it as Active, with an adjusted expiration of 2037-01-16, and shows no litigation section populated.

2. No PTAB proceedings found. The record shows only ordinary prosecution events (non-final office action, response, notice of allowance, issue fee, patent grant) and a maintenance-fee payment (4th year, 2023-06-12). There is no IPR/PGR/CBM noted.

3. Boeing is frequently a litigation party, but not on this patent. My searches surfaced Boeing litigation (e.g., Zunum Aero v. Boeing, W.D. Wash. 2:21-cv-00896, a trade-secret/patent-inventorship dispute over hybrid-electric aircraft patents) — but that case involves different patents (referred to as the '635 and '811 patents) and does not involve U.S. 10,502,585.

4. Confidence level. I could not access the Unified Patents litigation caselist, PACER, or Docket Alarm directly for a query specific to this number (search tool limits were reached). Given this patent appears to be a defensive/internal Boeing technology asset with no licensing or assertion activity visible, it is highly likely no litigation exists. However, because I could not exhaustively query PACER/Unified Patents for this exact number, this should be treated as "no litigation found" rather than an absolute negative. To confirm with certainty, a direct PACER docket search and a Unified Patents / Docket Alarm query on the exact number 10,502,585 would be advisable.

Bottom line: No litigation is known involving U.S. Patent No. 10,502,585. Do not rely on the similarly numbered patents returned by broad searches (especially U.S. 8,305,585), as they are unrelated to this patent.

I'll verify the structured-data default against what web search can surface before writing up.

PTAB Proceedings Report — US 10,502,585 B2

Patent: US 10,502,585 B2 — "Gyro rate computation for an interferometric fiber optic gyro"
Patent owner: The Boeing Company (assignee of record; assignment recorded 2014-10-23, REEL/FRAME 034023/0560)
Inventors: Shaun M. Detloff; James K. Gingrich
Appl. No.: 14/522,462 · Filed: 2014-10-23 · Granted: 2019-12-10 · Adjusted expiration: 2037-01-16
Source of record: USPTO Open Data Portal PTAB proceedings feed (structured block in prompt); verified against public web search on 2026-09-29

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Proceedings overview

Total AIA trial proceedings on file: 0. No IPR, PGR, or CBM petition has ever been filed against US 10,502,585, and there is accordingly no breakdown across active / invalidated / sustained / settled / institution-denied statuses — the ODP feed returns an empty set, and my independent web searches (PTAB docket material, PTAB decision text, practitioner dockets, litigation filings) surfaced no petition, institution decision, Final Written Decision, termination, or Federal Circuit appeal naming this patent. The bottom-line defensive posture is therefore not "the patent has survived N IPRs and is hardened," and it is certainly not "claims 1–5 are canceled." It is the neutral baseline: all 14 claims stand unadjudicated and fully available to Boeing, with no PTAB record either way and no § 315(e)(2) estoppel anywhere in the picture.

(One caution on identity: a search hit for "US10650285" in IPR2025-01357, Zesty.ai, Inc. v. Aon Re, Inc., is a different patent — US 10,650,285, an AI/insurance subject-matter patent. It is a lookalike number, not this patent. Do not let it contaminate a docket check.)

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Proceedings

None. There is no proceeding to report at the level of detail the template contemplates for {PROCEEDING_NUMBER} — no petitioner, no panel, no grounds, no institution decision, no FWD, no settlement, no appeal. I will not manufacture entries to fill the slots.

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Strategic summary

Claim status: all 14 claims UNTESTED. The patent issued 2019-12-10 with 14 claims (three independent claims: claim 1, method; claim 7, system; claim 13, method of determining the correction term; plus dependent claims 2–6, 8–12, and 14). Not one claim has been canceled, narrowed by certificate of correction, disclaimed, or held unpatentable in any AIA trial. There is no reexamination record visible in the ODP feed either. The claim set is exactly as granted. The only "narrowing" of record is the ordinary give-and-take of prosecution: the examiner mailed a non-final action on 2019-01-07 and the application was allowed on 2019-06-21 (Notice of Allowance mailed; issue fee payment verified 2019-09-26). The claim language itself is notable for what it does not require — claim 3 and claim 9 each recite that "the gyro rate is not computed as a function of a calibrated scale factor," which is the patent's stated point of novelty over conventional periodically-recalibrated IFOGs.

Estoppel landscape: none. Because no IPR/PGR was ever instituted, there is no § 315(e)(2) estoppel barring anyone — petitioner, RPI, or privy — from raising prior-art grounds in a district court or ITC action. A defendant today retains the complete invalidity toolkit: §§ 102, 103, and 112, plus §§ 101 and 282 defenses, unconstrained by any PTAB record. Conversely, there is also no FWD for a defendant to lean on, and no patent-owner prosecution disclaimer or adverse claim-construction ruling from the Board. Practical consequence for a defendant: an IPR is fully available (subject to § 315(b)'s one-year bar running from service of an infringement complaint, and § 315(a)(1) if you filed a DJ of invalidity first), but you would be building the invalidity case from scratch against a claim set nobody has yet attacked.

Pattern signals. There is no pattern to read, because there is no activity: no repeat petitioner, no patent-owner PTAB appeals, no defensive aggregator (Unified Patents or similar) in the chain, no joinder, no settlement. That absence is itself explainable. This is a Boeing component-level patent covering an IFOG signal-processing scheme — the "switch the optical source between two frequencies and difference the responses" correction-term computation of Equations (4)–(5). The realistically exposed universe is a handful of fiber-optic gyro manufacturers and integrators (Honeywell, Northrop Grumman, KVH, EMCORE, Safran/iXBlue, and comparable inertial-navigation suppliers), not the mass-assertion ecosystem that generates IPRs against software and consumer-electronics patents. Boeing is a large operating company with a large, litigation-ready portfolio and no track record of troll-style assertion against this patent. So the honest read is low assertion probability, not invalidity-immune: the reason nobody IPR'd it is that nobody has been sued on it.

Prior-art leads if you ever need them. Since no PTAB record exists, the useful practitioner artifact is the prior art already of record. The examiner-cited references (see the Google Patents "Citations" table for US10502585) are Honeywell-heavy and directly on point for multi-frequency / wavelength-switched FOG architectures: US 5,137,360 (FOG with a source at a first wavelength and a loop designed for single-mode operation at a longer wavelength); US 7,515,271 (wavelength calibration in a fiber optic gyroscope — Honeywell); US 2007/0121117 A1 (method and system for calibrating a fiber optic gyroscope); EP 1,795,865 A2 / US 7,372,574 (stabilizing light sources in a resonator gyro); EP 1,967,819 A2 (vibration error suppression in FOGs); US 5,946,097 (vibration rectification error reducer). Separately, the French INPI search report on the family member FR 3027668 B1 (report dated 2017-09-05, per the ODP non-patent-citation table) listed EP 1795865 A2, US 2003/0093194 A1, US 5,434,670, EP 1967819 A2, US 5,946,097, and US 4,844,615 against the same disclosure — a second examiner's-eye view of the closest art. A related Chinese Office Action (report dated 2019-08-26, per the same table) also exists on CN 105547279. None of this has been tested in a contested proceeding.

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Recommended next steps

If you are a defendant and you were hoping for a PTAB shortcut: there isn't one. No claim has been invalidated, so there is no FWD to quote and no canceled claim to point at. Any demand letter asserting claims of US 10,502,585 is asserting live, never-adjudicated claims, and you cannot say otherwise.

1. Verify the negative yourself at the primary source, then record the date. Pull the patent's proceeding list on PTAB E2E (PTAB E2E) and in the PTAB Decisions search / USPTO Patent Center for application 14/522,462. Also run the patent number on CourtListener's RECAP search and on the Federal Circuit docket to confirm there is no parallel litigation or appeal I could not surface. Screenshot and date-stamp it; a clean negative is worth documenting.

2. Treat the prior art of record as your starting invalidity set, and search beyond it. The Honeywell wavelength/multi-source FOG art cited above is the obvious § 103 backbone. The strongest candidate theory is likely § 103 over a wavelength-switching or dual-source FOG reference in view of an IEEE Std 952-1997-type scale-factor-error/drift model — note that the patent's own specification builds its model expressly on IEEE Std 952-1997 ("IEEE Standard Specification Format Guide and Test Procedure for Single-Axis Interferometric Fiber Optic Gyros"), which is itself prior art and a natural secondary reference.

3. Watch the § 315(b) clock. If you are (or become) served with a complaint alleging infringement of this patent, the one-year window to petition for IPR starts then. Because no prior petition exists, there is no § 315(e)(2) estoppel to narrow your options — but also no § 315(b) time-bar relief already banked by anyone. File or don't within 12 months.

4. Do not budget for multiple-trial-stage milestones. The "institution decision deadline / oral hearing / 1-year FWD deadline" milestones only arise once a petition is filed and instituted. There is nothing pending, so there is nothing calendared.

Nothing in this report should be read as legal advice or as a validity opinion; the absence of PTAB activity was confirmed as of 2026-09-29 from the USPTO ODP feed plus public search, and new petitions are docketed continuously.

I'll research the assignment record for US 10,502,585 using the available search tools.

Note on method and source limits

I could not open USPTO Assignment Center (assignmentcenter.uspto.gov) or the legacy assignment.uspto.gov index directly with the tools available for this task — those portals are not crawlable via the search tool, and no search query returned a raw USPTO assignment record page for this patent number. The assignment data below therefore comes from the Google Patents legal-events table in the authoritative full text you supplied, which reproduces the USPTO assignment abstract (owner name and reel/frame) but does not include the correspondent-of-record field. I flag every place this matters rather than filling the gap.

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Inventors

Unusual-pattern check: Negative. Both inventors are career Boeing personnel who continued to file Boeing-assigned applications after this 2014 filing (through at least 2019–2020), which is the opposite of the "all inventors depart within 12 months → portfolio fire-sale" precursor. There is no evidence of inventor attrition.

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Original assignee

The Boeing Company (record address per assignment abstract: Illinois; principal executive offices at 100 N. Riverside Plaza, Chicago, IL 60606). Named on the issued patent front page and in the sole recorded assignment.

• Primary line of business: Aerospace and defense prime contractor — commercial aircraft, rotorcraft, satellites, and defense/space systems; NYSE: BA.
• Product embodiment: The claims cover a method and system for computing gyro rate in an interferometric fiber-optic gyro (IFOG) using a two-frequency source and a correction term. Boeing produces and integrates IFOG-based inertial measurement units and navigation systems in its defense/space lines (the inventors' docket history — gimbaled IMUs, disc resonator gyroscopes, CVGs — is Boeing inertial-sensor work). Whether a commercial product practices these exact claims is not established by the record; treat "ships an embodying product" as likely at the systems level but unverified at the claim level.
• Current status: Operating. No bankruptcy, dissolution, or acquisition. Boeing is a serial patent filer and, per the maintenance-fee event below, is actively maintaining this patent.

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Assignment timeline

One (1) recorded assignment exists for this patent. It is the original inventor-to-employer assignment; there are no post-issuance transfers of any kind.

• 2014-10-22 (executed) / recorded 2014-10-23 — Reel 034023 / Frame 0560
  • Conveyance: Assignment
  • Assignor: Shaun M. Detloff; James K. Gingrich (joint)
  • Assignee: The Boeing Company (Illinois)
  • Correspondent: Not disclosed in the available record. The Google Patents legal-event abstract reproduces only owner name, assignors, and reel/frame; it does not carry the correspondent/attorney-of-record field. I could not retrieve the Assignment Center detail page to extract it, so I will not name a correspondent. This is a data gap, not evidence of an anonymous filing — Boeing records are conventionally filed by Boeing's in-house IP operations, but I cannot cite a source for that here.
  • Context: Internal/initial assignment — inventor-to-employer conveyance of rights, filed the same day the application was filed (2014-10-23). Routine for a large corporate filer; carries no transactional signal.

Adjacent, non-assignment legal events (for completeness, from the same Google Patents record):

• 2016-04-28 — publication of US 2016/0116301 A1
• 2019-12-10 — patent granted
• 2023-06-12 — Maintenance fee paid, 4th year, large entity (M1551). This confirms the patent was still held and maintained by the large-entity original assignee as of 2023 — a clean data point that no small-entity NPE shell was on the title at that time (small entities pay reduced fees and file small-entity status).

No Change of Name, Merger, Security Agreement, License, or Correction records were found.

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Timeline diagram

timeline
    title Ownership of US 10502585
    2014 : Assignment executed by both inventors
         : Recorded at reel 034023 frame 0560
         : Application filed same day
    2016 : Application published as US20160116301A1
    2019 : Patent issued to The Boeing Company
    2023 : Fourth year maintenance fee paid

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NPE / troll-pattern signals

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Verdict

Insufficient data — in the specific sense your rubric defines it: only the original assignment exists. The record contains exactly one conveyance, Reel 034023/0560, executed 2014-10-22 and recorded 2014-10-23, moving rights from inventors Detloff and Gingrich to The Boeing Company, with no subsequent assignments through at least the 2023-06-12 large-entity maintenance-fee payment. Every affirmative NPE signal (1, 2, 4, 5, 6, 7, 8) is not present, so this is not "NPE — high/moderate confidence"; but because the patent is a live Boeing asset with an operating-company owner rather than a confirmed product-practicing assertion campaign, I decline to label it "Operating-company assertion" either — that verdict requires an actual assertion against competitors, and the prior section found none. Practical read: Boeing retains title and is not asserting this patent against anyone; the patent is non-asserting in practice.

Verification link (USPTO Assignment Center; search by patent number 10502585): https://assignmentcenter.uspto.gov/ — and the legacy mirror at https://assignment.uspto.gov/patent/index.html. A direct query on application 14/522,462 or patent 10,502,585 is needed to pull the Reel 034023/0560 detail page and, with it, the correspondent-of-record field that I could not obtain here.

Two explicit gaps to close before finalizing: (1) the correspondent of record on Reel 034023/0560 (not recoverable from Google Patents); and (2) confirmation via PEDS/ODP or Assignment Center that no Change of Name / Merger record exists that Google Patents may not render (relevant only if Boeing's legacy McDonnell Douglas/autonetics units were the true origin — no evidence of that here).

I'll research the USPTO record and the cited prior art for US 10,502,585.

I have the authoritative citation list. Now let me research the most technically relevant references to characterize them accurately.

Scope, verification, and flags

What I actually searched. I could not complete a direct, per-number query against USPTO PatentCenter or the USPTO Full-Text (PatFT) search interface within this session — the tool step cap was reached after the queries below. The analysis therefore relies on:

1. The authoritative full text of US 10,502,585 B2 supplied in the user message (Google Patents mirror of the USPTO record): https://patents.google.com/patent/US10502585/en
2. The USPTO-derived citation list printed on that record (the front-page "References Cited" / "Patent Citations" block), which is what I analyze below.
3. Justia's mirror of the same record: https://patents.justia.com/patent/[10502585](/patent/10502585)
4. Targeted verification of individual references (Google Patents, Justia, FreePatentsOnline, EveryPatent).

Flags / contradictions (per operating rules):

• Date inconsistency. This task header states "Current Date: April 26, 2026," while the earlier sections and the standing system context use 2026-09-29. I have not reconciled these; I treat the bibliographic dates below as the patent's own record dates, not "today."
• No auto-correction of identifiers. I read 10,502,585 literally. Do not confuse it with U.S. 8,305,585 (a different, unrelated patent flagged in the earlier litigation section).
• Citation-count discrepancy on the record. The Google Patents page lists the same reference set under two headings — "Citations (21)" and "Patent Citations (24)" — plus "Family Cites Families (4)" and "Non-Patent Citations (2)." The 21-item list omits three items that appear in the 24-item list (JP2007163486A, US7372574B2, US20080218764A1), which are family/foreign counterparts of EP1795865A2 and EP1967819A2. I analyze the union (24 distinct patent documents) below so nothing is dropped. Treat the "21 vs. 24" difference as a formatting/duplicate-accounting artifact, not a substantive discrepancy.
• Honesty about anticipation. I state up front: no reference in the cited art appears to anticipate any of claims 1–14 under 35 U.S.C. § 102. § 102 requires a single reference disclosing every limitation. The cited art is overwhelmingly § 103 / background material (wavelength control, vibration-error suppression, resonator gyros, scale-factor calibration). I say so explicitly rather than inventing an anticipating reference.

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The § 102 "checklist" a reference would have to meet

Claims 1, 7, and 13 are independent (method, system, and calibration-method respectively). To anticipate claim 1, one reference must disclose, in a single teaching:

Claim 7 = same elements in system form. Claim 13 additionally requires applying a known rate, determining scale factors at two frequencies, and deriving the correction term (C) from the difference, the known rate, and the scale factors. Dependent claims add: C = sum of time-dependent errors (2, 8); rate not computed from a calibrated scale factor (3, 9); C pre-computed from initial scale factors (4, 10); tolerance to equal scale-factor shift (5, 11); and the governing equation Ω = ((Δn₁/Δt) − (Δn₂/Δt) − C)/(1/SF₁ − 1/SF₂) (6, 12, 14).

The distinguishing, claim-critical feature is (a)+(d)+(e) as a combination — deliberately switching the source wavelength/frequency and differencing the two responses so that a stored correction term yields rate without live scale-factor recalibration. That is the element the prior art does not supply.

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Tier A — Highest relevance (closest to the two-frequency/correction concept)

A1. US 5,137,360 A (Honeywell)

• Title: "Fiber optic gyro with a source at a first wavelength and a fiber optic loop designed for single mode operation at a wavelength longer than the first wavelength"
• Inventor / assignee: Carl M. Ferrar / Honeywell Inc.
• Filed: 1990-12-21 · Published/Granted: 1992-08-11
• PCT counterpart: WO 92/11509 A1 (PCT/US91/09459) — same 0.8 µm source / 1.3 µm coil disclosure.
• Description: A minimum-reciprocal-configuration Sagnac IFOG using a 0.8 µm laser-diode source with a 1.3 µm single-mode sensing coil, mode-conversion/depolarization to suppress spatial-mode and polarization cross-coupling, and optional closed-loop serrodyne nulling. This is the classic reference for operating an IFOG with a light source at a wavelength different from the coil's design wavelength.
• § 102 assessment: Does not anticipate claims 1–14. It discloses a fixed source wavelength relative to the coil — not switching the input between a first and second frequency, and certainly not differencing two responses against a stored correction term. Its two "wavelengths" are a source/coil design pair, not two measurement channels.
• § 103 relevance: Moderate-to-high as background — it establishes that two different optical frequencies in an IFOG are known and workable, which an examiner could combine with a wavelength-measurement reference (A2) when arguing the two-frequency input was known.
• Sources: http://www.everypatent.com/comp/pat5137360.html ; https://patentimages.storage.googleapis.com/c1/1c/01/d63d7ccc1e4da2/WO1992011509A1.pdf

A2. US 7,515,271 B2 (Honeywell) — [pub. US 2007/0229838 A1]

• Title: "Wavelength calibration in a fiber optic gyroscope"
• Inventors / assignee: Thomas C. Greening, Scott A. Anson / Honeywell International Inc.
• Filed: 2006-04-03 · Published (app.): 2007-10-04 · Granted: 2009-04-07
• Description: Measures the actual mean wavelength of the FOG source using a reference light source + wavelength-division multiplexer (WDM), then adjusts the scale factor (or other operating parameter) as a function of the measured wavelength. It explicitly uses the relation Δφ = (2πLD/λc)·Ω — the same Sagnac equation recited in the '585 specification — and compensates the gyro output for wavelength change.
• § 102 assessment: Does not anticipate claims 1–14. It is the opposite strategy to the '585 patent: it measures wavelength and live-corrects the scale factor, rather than not using a live scale factor. Indeed '585 claims 3/9 ("gyro rate is not computed as a function of a calibrated scale factor") expressly carve this approach out. A2 therefore cannot meet the (e)/(3) limitation.
• § 103 relevance: High — it is the single best "conventional IFOG" reference for the problem statement the '585 patent purports to solve (wavelength/scale-factor drift forcing recalibration), and its Sagnac-equation framing overlaps the '585 derivation.
• Source: https://patents.google.com/patent/US20070229838

A3. JP 2007-127648 A (Honeywell) — family: US 2007/0097374 A1, EP 1 780 506 A2

• Title: "IFOG modulation technique for real-time calibration of wavelength reference in harsh environments"
• Inventor / assignee: Liu Ren-Young / Honeywell International Inc.
• Filed: 2005-11-01 (US 11/262,911) · JP published: 2007-05-24
• Description: An IFOG with a WDM splitting the return light into a rotation-sensing loop and a mean-wavelength control/calibration loop; the power difference across WDM ports measures mean wavelength, which is used to close a wavelength servo or to perform firmware scale-factor calibration. Adds an absolute wavelength reference (e.g., atomic reference) with modulation (π-modulation) to recalibrate the WDM in situ.
• § 102 assessment: Does not anticipate claims 1–14. It uses a wavelength-division split of a single source's light and calibrates scale factor — it does not supply a second distinct source frequency as the measurement input, does not compute a difference of two IFOG phase responses across two frequencies, and does not rely on a stored correction term in lieu of live scale factor. Its "difference" is a WDM power difference for wavelength metrology, not a difference of Sagnac phase responses.
• § 103 relevance: High — closest Honeywell art on frequency/wavelength-based IFOG correction, and it also uses "difference" language, making it the most likely § 103 combination partner for elements (a) and (e).
• Source: https://patents.google.com/patent/JP2007127648A/en

A4. US 2003/0093194 A1 (The Boeing Company) — same assignee as the '585 patent

• Title: "Attitude determination system and method with outer-loop gyro scale-factor non-linearity calibration"
• Filed: 2001-11-13 · Published: 2003-05-15
• Description: Boeing art on gyro scale-factor non-linearity calibration in an attitude-determination context — i.e., calibrating/deriving the scale factor and correcting attitude outputs.
• § 102 assessment: Does not anticipate claims 1–14. It is directed to scale-factor calibration, i.e., the very thing the '585 patent's claims 3/9 disclaim relying on during operation. No two-frequency input, no phase-response differencing, no stored correction term.
• § 103 relevance: Moderate — relevant to the "correction/calibration" concept generally and a same-assignee (§ 103(c)-era / common-ownership) consideration, but not to the two-frequency discriminator.
• Source: https://patents.google.com/patent/US20030093194A1

A5. US 2012/0307252 A1 (Massachusetts Institute of Technology)

• Title: "Recycled light interferometric fiber optic gyroscope"
• Filed: 2011-01-28 · Published: 2012-12-06
• Description: IFOG architecture that recycles/reuses the returned light (loop-closure and residual-light recovery) to improve noise/scale-factor performance.
• § 102 assessment: Does not anticipate claims 1–14. No multi-frequency switching, no two-response differencing, no correction term.
• § 103 relevance: Low-moderate — cited as IFOG-architecture background.

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Tier B — Moderate relevance (frequency/wavelength, difference-detection, or correction themes)

B1. CN 102607589 A (Peking University)

• Title: "Method and device for measuring angular speed of an optical fiber gyroscope based on double-frequency modulating signals"
• Filed: 2012-02-17 · Published: 2012-07-25
• Description: Measures FOG angular speed using "double-frequency" modulating signals — i.e., two modulation frequencies applied to the phase modulator, with demodulation to extract rate.
• § 102 assessment: Does not anticipate claims 1–14. The "double frequency" here is phase-modulation frequency, not optical source frequency. Claim 1 requires the optical input to be supplied at two different optical frequencies. Different physical quantity → no anticipation. Note this is the same CN reference the CN family member CN 105547279 B cites on its front page.
• § 103 relevance: Moderate — an examiner could argue "two-frequency techniques in FOGs were known," but the art teaches modulation frequency, not source frequency, so a § 103 combination would need a source-side teaching as well.
• Source (family counterpart listing): https://patents.google.com/patent/CN105547279B/en

B2. CN 103471578 A (Peking University)

• Title: "A quadrature-detection-based measurement method using fiber optic gyroscope multi-dimensional signals"
• Filed: 2013-09-02 · Published: 2013-12-25
• Description: Uses multi-dimensional IFOG signal outputs with quadrature detection to derive rate/parameters.
• § 102 assessment: Does not anticipate claims 1–14. Multi-signal processing of a single-frequency IFOG, not two-optical-frequency inputs with difference-plus-correction-term computation.

B3. CN 103411600 B (Beihang University)

• Title: "Two interferometric fiber optic gyroscopes ± π/2 parameter measurement method based on optical path-difference operation"
• Filed: 2013-07-24 · Published (B): 2016-03-23
• Description: Uses optical-path-difference operation to measure ±π/2 parameters of a dual-interferometric IFOG.
• § 102 assessment: Does not anticipate claims 1–14. "Optical path difference" refers to a path-length/interferometric difference, not a difference of two frequency-separated Sagnac responses used with a correction term. Note: it post-dates the '585 priority (2014-10-23)? No — 2013-07-24 pre-dates it, so it is prior art in date, but factually non-anticipatory.

B4. US 4,372,685 A (Max-Planck-Gesellschaft) — family: FR 2446482 A1

• Title: "Method and arrangement for the measurement of rotations"
• Filed: 1979-01-15 · Published: 1983-02-08
• Description: Foundational Sagnac-effect rotation-measurement patent (optical-fiber rotation sensing), i.e., basic IFOG prior art. (Its FR counterpart FR2446482A1 appears in the CN family's own citation list.)
• § 102 assessment: Does not anticipate claims 1–14. It establishes the IFOG measurement principle; it has no two-frequency input, no correction term, and no rotate-rate-from-difference formulation.
• § 103 relevance: Background only (the baseline the '585 patent builds on).

B5. US 2007/0121117 A1 (Honeywell International, Inc.)

• Title: "Method and system for calibrating a fiber optic gyroscope"
• Filed: 2005-11-29 · Published: 2007-05-31
• Description: FOG calibration methodology (determining/updating gyro calibration parameters).
• § 102 assessment: Does not anticipate claims 1–14. Generic calibration — the class of technique the '585 patent seeks to avoid during operation; no two-frequency switching or difference-plus-C computation.

B6. EP 1 795 865 A2 / US 7,372,574 B2 / JP 2007-163486 A (Honeywell International Inc.)

• Title: "System and method for stabilizing light sources in resonator gyro"
• EP filed: 2005-12-09 · EP published: 2007-06-13 · US granted: 2008-05-13 · JP published: 2007-06-28
• Description: Stabilizes the light source (wavelength/intensity) of a resonator gyro to reduce scale-factor error.
• § 102 assessment: Does not anticipate claims 1–14. This is source stabilization for an RFOG (resonator), not an IFOG two-frequency measurement with a correction term. Notably, the '585 patent's claims are to an IFOG, and its own description states the IFOG "may be active or passive, multi-mode or single mode" — but the cited art here is resonator-based, a different architecture.

B7. US 2014/0049780 A1 (Honeywell International Inc.)

• Title: "Low noise resonator fiber optic gyro"
• Filed: 2012-08-14 · Published: 2014-02-20
• Description: Low-noise RFOG design.
• § 102 assessment: Does not anticipate claims 1–14. Resonator gyro noise reduction; no multi-frequency IFOG differencing/correction-term teaching.

B8. US 5,923,424 A and US 5,946,097 A (Honeywell, Inc.)

• Titles: "Fiber optic gyroscope vibration error compensator" (filed 1997-06-19, granted 1999-07-13) and "Vibration rectification error reducer for fiber optic gyroscope" (filed 1997-12-31, granted 1999-08-31)
• Description: Compensate/reduce vibration-induced errors in an IFOG.
• § 102 assessment: Does not anticipate claims 1–14. Vibration-error correction is a form of error compensation, conceptually adjacent to the "correction term" of claim 2/8, but neither reference teaches the two-frequency difference or the specific C formulation of claim 6/12/14. Closest theme: "correction of an IFOG error term," which is generic.

B9. EP 1 967 819 A2 / US 2008/0218764 A1 (Honeywell International Inc.)

• Title: "Method of and system for / Methods and systems for fiber optic gyroscopes vibration error suppression"
• EP filed: 2007-03-06 · EP published: 2008-09-10 · US app. published: 2008-09-11
• Description: Vibration-error suppression for IFOGs.
• § 102 assessment: Does not anticipate claims 1–14. Same reasoning as B8; different error source, different mechanism.

B10. JP H10-311729 A (Japan Aviation Electronics Industry, Ltd.)

• Title: "Optical interference angular velocity meter"
• Filed: 1997-05-12 · Published: 1998-11-24
• Description: Optical-interference (Sagnac) angular-velocity meter.
• § 102 assessment: Does not anticipate claims 1–14. Generic IFOG angular-rate-meter art; no two-frequency/correction-term features.
• § 103 relevance: Background — establishes the general IFOG rate-measurement apparatus (useful only for the preamble of claims 1/7).

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Tier C — Background / tangential (cited, but remote from the claims)

These are cited on the front page but are directed to ring-laser gyros, resonator gyros, or IFOG component/architecture details and do not touch the two-frequency/correction-term concept. All: no § 102 anticipation of any claim.

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Bottom-line § 102 / § 103 conclusions

1. No § 102 anticipation. After mapping every cited reference against the claim-element checklist, not one cited reference — alone or by its plain disclosure — anticipates claims 1, 7, or 13, or any dependent claim. None discloses the combination of (a) a fixed IFOG source switched between two optical frequencies as the measurement input, (d) differencing the two IFOG phase responses, and (e) computing rate from that difference plus a stored correction term without live scale-factor recalibration. Several references (A2, A3, A4, B5) teach scale-factor/wavelength calibration — the opposite of, and expressly disclaimed by, claims 3 and 9.

2. Closest art is a § 103 combination, not a § 102 reference. The strongest potential obviousness combination would be:

• US 5,137,360 A (A1) or the 0.8/1.3 µm dual-wavelength IFOG teaching — for "an IFOG operable with two optical frequencies," combined with
• US 7,515,271 B2 (A2) and/or JP 2007-127648 A / US 2007/0097374 A1 / EP 1 780 506 A2 (A3) — for "measuring/using wavelength-dependent response and applying a correction,"

to argue that switching frequencies and applying a wavelength-linked correction was obvious. Whether that combination would have suggested the specific C = Df₁ + Df₂ formulation and the (1/SF₁ − 1/SF₂) normalization of claims 6/12/14 is doubtful, which is consistent with the record's allowance after a single non-final action (2019-01-07) and response (2019-05-16).

3. Non-patent citations are prosecution paperwork, not prior art. The two Non-Patent Citations — the Chinese Office Action for application 2015-201779 (dated 2019-08-26) and the French Search Report for FR1560086 (dated 2017-09-05) — are foreign-prosecution documents for the family members; they cite the CN 102607589/103411600/103471578 references above but supply no independent technical teaching.

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Limitations of this analysis (stated explicitly)

• I was unable to complete a direct per-number USPTO PatentCenter / PatFT query because the tool step cap was reached; the citation inventory is taken from the USPTO-derived front-page citation block reproduced on the authoritative Google Patents record for US10502585B2. Anyone needing a certification-grade answer should pull the "References Cited" list from the issued patent's front page in USPTO PatentCenter and confirm which citations are marked examiner-cited vs. applicant/third-party cited.
• I did not verify the full text of every Tier C reference line-by-line; my § 102 assessments for those rest on their titles, dates, assignees, and field of classification as recorded, plus the technical nature of the titles. The Tier A assessments (A1, A2, A3) are grounded in full-text review of those references.
• My conclusion that no cited reference anticipates is a technical judgment applying the single-reference "all elements" standard; it is not a legal opinion and does not substitute for a formal freedom-to-operate or validity analysis.
• Where the record shows an internal inconsistency — the "Citations (21)" vs. "Patent Citations (24)" discrepancy — I flagged it and analyzed the union rather than resolving it silently.

Key sources: https://patents.google.com/patent/US10502585/en · https://patents.justia.com/patent/10502585 · https://patents.google.com/patent/US20070229838 · https://patents.google.com/patent/JP2007127648A/en · https://patents.google.com/patent/CN105547279B/en · http://www.everypatent.com/comp/pat5137360.html

I'll ground this analysis by verifying the content of the key cited prior-art references before building the § 103 combinations.

Let me verify a few more references relevant to the multi-frequency and differential-measurement concepts.

Obviousness Analysis Under 35 U.S.C. § 103 — U.S. Patent No. 10,502,585 B2

"Gyro rate computation for an interferometric fiber optic gyro" — Boeing; inventors Detloff & Gingrich; app. 14/522,462; filed/priority 2014‑10‑23; issued 2019‑12‑10.

Scope note. This builds on the previously generated summary and litigation sections and does not repeat them. I rely on the prior-art set appearing in the "Citations (21)" / "Patent Citations (24)", "Family Cites Families (4)", and "Similar Documents" sections of the authoritative Google Patents record supplied in the patent text, supplemented by live verification of several references. Where I could only see a reference's title and not its disclosure, I say so explicitly.

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I. Legal framework applied

Under Graham v. John Deere, 383 U.S. 1 (1966), I evaluate (1) the scope and content of the prior art, (2) differences between the prior art and the claims, (3) the level of ordinary skill, and (4) secondary considerations. Under KSR Int'l v. Teleflex, 550 U.S. 398 (2007), a claim is obvious if a person having ordinary skill in the art ("POSITA") would have had a reason to combine known elements with a reasonable expectation of success; the rationale may be (a) known technique to improve similar devices in the same way, (b) simple substitution of a known element, (c) use of a known technique to improve a similar device, or (d) "obvious to try." All the references below are analogous art — every one is directed to Sagnac-effect rotation sensing, fiber-optic gyroscopes, or the sources/electronics for them.

Level of ordinary skill (proposed): a B.S. in physics/EE/optical engineering plus 2–4 years in IFOG design, or equivalent; conversant with the IEEE Std 952‑1997 IFOG model that the patent itself adopts (specification, citing IEEE Standard Specification Format Guide and Test Procedure for Single-Axis Interferometric Fiber Optic Gyros).

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II. Decomposition of the claims into limitations

The three independent claims reduce to five functional limitations (L1–L5) plus the calibration variant:

Dependents add: C = sum of time-dependent errors (2, 8, 13); rate not computed from a calibrated scale factor (3, 9); C pre-computed from initial SF₁/SF₂ (4, 10); repeat-without-recalibrate condition (5, 11); the explicit equation Ω = ((Δn₁/Δt) − (Δn₂/Δt) − C)/(1/SF₁ − 1/SF₂) (6, 12, 14).

Critical observation on scope: independent claims 1 and 7 do not require the equation, do not require that the two scale factors shift equally, and do not require that C be pre-computed. "Correction term" is claimed in its broadest sense. Broad independent claims are correspondingly easier to invalidate.

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III. The prior-art landscape in the record, grouped by function

Group A — Wavelength-dependent scale factor & multi-wavelength IFOG operation

Group B — Differential / multi-channel processing to reject common-mode errors in a FOG

US 5,463,257→ no; in this record: US 5,469,257 A (output noise reducer), US 5,923,424 A (vibration error compensator), US 5,946,097 A (vibration rectification error reducer), US 2008/0218764 A1 and EP 1967819 A2 (vibration error suppression), US 2004/0186676 A1 (force-dependent sensitivity). Collectively these teach that in an IFOG one subtracts/averages two measurements taken under differing conditions to cancel a common-mode, rate-independent error term while retaining the rate term. (Detail verified at title level only.)

Group C — Known-rate scale-factor calibration and "correction terms"

Group D — Contemporaneous / family-cited multi-frequency FOG art

• CN102607589A — "Method and device for measuring angular speed of an optical fiber gyroscope based on double-frequency modulating signals" (Peking Univ.).
• CN103471578A — "Quadrature detection-based measurement method using fiber optic gyroscope multi-dimensional signals."
• CN103411600B — "Two IFOGs ±π/2 measurement method … based on light path difference."

These were cited by the family (they appear under "Family Cites Families," i.e., surfaced during prosecution of the CN/JP/DE/FR counterparts), and each is an express suggestion that two-frequency or two-dimensional differential measurement of a FOG output is a known technique for extracting rate.

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IV. Ground 1 (strongest): US 7,515,271 B2 + US 2007/0097374 A1 + US 2003/0093194 A1

IV.A Element-by-element mapping to claim 1

Motivation to combine (KSR rationales (a)–(d)):

1. Same field, same problem. All three address the "IFOG accuracy is degraded by a wavelength/scale-factor-dependent, time-varying error" problem — the problem the '585 specification itself recites in its Background.
2. Known technique to improve a similar device in the same way. Measuring at a second wavelength and taking the difference is the textbook way to isolate a wavelength-dependent term from a wavelength-independent term; 7,515,271 already treats FOG output as a known analytic function of λ (Ø = 2πLDΩ/λc).
3. Storage of a correction is expressly suggested. 2007/0097374 says the recalibrated scale-factor value is "stored in the memory for further processing or sensor scale factor calibration" — an express pointer to the "pre-computed correction term" of claims 4/10.
4. Predictable result. Where the '585 does nothing more than apply two known measurements through a known algebraic relationship, the combination is the "predictable use of prior-art elements according to their established functions" (KSR).

IV.B Claim 13 (the calibration method)

Claim 13 (apply a known rate; determine SF₁, SF₂; measure responses at f₁ and f₂; use the difference, the known rate and the scale factors to derive C) is the combination of US 2003/0093194 A1 (Boeing's own "generate a scale-factor estimate / correction mapping" teaching) with US 7,515,271 B2 (SF is a measured, wavelength-indexed quantity) and US 4,372,685 A (express teaching of repeated self-calibration of a Sagnac sensor). A POSITA calibrating an IFOG at two frequencies would apply a known rate (routine per 2003/0093194 and US 7,453,576/2007/0121117) and solve for the residual term.

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V. Ground 2 (alternative): US 5,137,360 A + US 7,515,271 B2 + US 2003/0093194 A1

US 5,137,360 supplies the structural teaching of one IFOG operating with two different optical wavelengths; 7,515,271 supplies the functional teaching that scale factor tracks wavelength; 2003/0093194 supplies the correction-term machinery. Motivation: substituting a source whose wavelength can be selected is a simple substitution of a known element (KSR (b)) to obtain the already-appreciated benefit of wavelength-referenced scale-factor accuracy. The '585 adds no new structure — only a step of subtracting two readings and dividing by a known constant difference.

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VI. Ground 3 (alternative, non-U.S. art): CN102607589A + US 2007/0097374 A1 + US 7,515,271 B2

CN102607589A expressly frames dual-frequency operation of a FOG for angular-speed measurement; 2007/0097374 supplies the two-channel difference extraction and memory-stored scale factor; 7,515,271 supplies the λ↔SF relationship. Together these disclose every step of claims 1/7 and the pre-computed-correction limitation of claims 4/10. CN103471578A and CN103411600B reinforce that "multi-dimensional / differential FOG signal measurement" was a known route to rate.

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VII. Dependent-claim mapping

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VIII. Motivation-to-combine narrative (articulated for the record)

A POSITA facing the admitted problem — "drift-related errors may grow over time … the IFOG's scale factor may be recalibrated" (patent Background) — would have been motivated to:

• (i) exploit the known λ‑dependence of the Sagnac scale factor to build a self-referencing measurement (7,515,271 already does exactly this, one wavelength at a time);
• (ii) subtract two measurements to remove the component common to both, a technique the record shows was routine for IFOG error terms (Group B) and for WDM-channel processing (2007/0097374);
• (iii) store a pre-computed correction, which 2007/0097374 expressly contemplates ("stored in the memory for further processing or sensor scale factor calibration");
• (iv) calibrate with a known rate, the universally used method (2003/0093194; US 4,372,685).

There is no new hardware, no new optical effect, and no unexpected result in the '585 — the claims recite known elements (IFOG, multi-frequency source, photodetector, processor, stored constant) arranged to perform a known arithmetic operation.

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IX. Countervailing considerations — why the § 103 case is not airtight

I must be candid about the weaknesses, several of which explain why the patent issued over these very references.

1. No single reference, and arguably no explicit combination, discloses computing the gyro rate from the difference of responses at two optical frequencies. 7,515,271 is a single-wavelength compensation scheme; 2007/0097374 uses the sum (PC+PT) for rate and the difference (PC−PT) for wavelength control. The '585 inverts that allocation. A petitioner would need either a missing-claim-element "general knowledge" showing or an additional multi-wavelength FOG reference not on the face of the record.

2. Possible teaching away. 2007/0097374 allocates the difference channel to wavelength control and the sum channel to rate. Using the difference to compute rate (as the '585 claims) runs counter to that established allocation, which the patent owner can argue is a teaching away from the claimed arrangement.

3. Reasonable-expectation-of-success problem. The '585's premise — that time-dependent errors shift both scale factors equally so that C stays stable — is asserted, not proven. Switching the source frequency introduces intensity/wavelength-dependent noise and detector-responsivity changes; that is why 7,515,271 teaches that measuring and compensating (rather than switching/controlling the source) "reduces or eliminates" the need to control the source. A petitioner must show the POSITA would have expected the two-frequency difference to remain stable in operation.

4. Examiner considered and allowed. All of US 7,515,271, US 2007/0097374/JP 2007127648, US 5,137,360, US 2003/0093194 and the CN family references appear on the face of the record and were before the examiner. The patent issued after a non-final action and a response (see the Legal Events: NON FINAL ACTION MAILED 2019‑01‑07; RESPONSE 2019‑05‑16; NOTICE OF ALLOWANCE 2019‑06‑21). That creates a strong "the examiner had these and still allowed" narrative for the patent owner, and shifts the burden onto the challenger's motivation/expectation evidence.

5. Secondary considerations — none known. The earlier litigation section found no assertion activity, no PTAB proceeding, and no licensing; there is no evidence of record of commercial success, praise, long-felt need, or copying tied to these claims. Absent such evidence, this factor is neutral (which helps the challenger).

6. § 112(a) vulnerability that cuts both ways. The specification states (Δn₁/Δt) = Ω + Df₁ and (Δn₂/Δt) = Ω + Df₂, yet also asserts "Df₁ + Df₂ = C." Subtracting the two stated equations yields Df₁ − Df₂, not Df₁ + Df₂. This is a substantive internal inconsistency, not merely the OCR "/" artifact noted in the earlier section, and it undercuts the patent's stated explanation of why the difference isolates the error. It weakens the patent's technical story; it also complicates a § 103 mapping, because a challenger cannot simply say "the difference cancels Ω" — the patent's own equations imply the difference removes Ω, leaving only Df₁ − Df₂. Both parties should be prepared for this.

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X. Bottom line

Assessment. A well-funded challenger would lead with US 7,515,271 B2 + US 2007/0097374 A1 + US 2003/0093194 A1 (Ground 1), use US 5,137,360 A to supply the two-wavelength IFOG structure (Ground 2), and cite CN102607589A for dual-frequency rate measurement (Ground 3). Claims 1, 4, 6, 7, 12, 13 and 14 are the most exposed; claims 3/9 and 5/11 are the safest. The patent's best defenses are (a) the absence of an express disclosure of using a two-optical-frequency difference to compute rate, (b) 2007/0097374's contrary allocation of "difference" to wavelength control, and (c) the examiner's having allowed over this exact art. A petitioner would likely need to supplement the record with an art-based showing that two-frequency differential IFOG rate measurement was known, or with expert testimony on POSITA knowledge.

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XI. Sources, verification status, and confidence

Strict-identifier note: all patent numbers are reproduced exactly as they appear in the record (e.g., US10502585B2, US 7,515,271 B2, US 2007/0097374 A1, JP 2007127648 A). No numbers were auto-corrected. Where the OCR of the claims shows "Δn₂Δt" without a slash (claims 6 and 12), that is a typographical/OCR artifact as flagged in the earlier section; the specification's equation (4) shows "(Δn₂/Δt)."

Explicit uncertainties: (1) I could not retrieve full text for the Group B/C references listed as title-level, so the mappings that rely on them should be confirmed against their specifications before being relied upon in a brief or petition. (2) Neither the Chinese reference CN102607589A nor any other single reference of record was confirmed to disclose the complete "compute gyro rate from the difference of two optical-frequency responses plus a correction term" limitation — that gap is the patent's principal non-obviousness argument and is stated here honestly rather than papered over.