US 10648876

I'll search for authoritative information on US 10648876 before summarizing.

Verification of the search

I searched for the literal identifiers 10648876, US10648876, and US10648876B2, including targeted queries against litigation/PTAB/CAFC dockets. No district court case, ITC investigation, IPR/PGR, or CAFC appeal involving US 10,648,876 was found. The only "hits" for the bare string 10648876 in unrelated sources were numeric coincidences (a Czech contract registry ID, a UK company number, a Russian shoe-registry entry, a DOI, and a PubMed ID 10648876 for an unrelated kappa-opioid paper). Those are not the patent and I did not treat them as such. Note also that other OFS Fitel litigations exist (e.g., OFS Fitel v. Sterlite Optical Technologies, N.D. Ga. 1:02-cv-02149; the DSM IP Assets ITC §337 action) but neither involves this patent number, and I did not conflate them.

Caveat on method: I could not query PACER/PatentCenter directly from this session. So "no litigation found" means no public web-visible record, not a certified litigation-free status. Treat that as a limitation, not a finding of non-assertion.

US 10,648,876 B2 — bibliographic record

Source: https://patents.google.com/patent/US10648876/en and https://patents.justia.com/patent/[10648876](/patent/10648876)

Abstract (as printed): An optical cable comprising a plurality of cable sensors helically wound around a support and an outer jacket disposed on/surrounding the cable sensors. Each cable sensor comprises an optical fiber having an optical core with cladding, a primary coating, a deformable material surrounding the fiber, and an outer tube surrounding the deformable material; the fiber is of equal length to the outer tube; and allowable strain at zero fiber stress is given by equations (1) and (2), where ε = π²dD/p² ≈ 10dD/p², and percent elongation/contraction = ε × 100, with d = fiber clearance in the tube, D = average pitch diameter, p = average pitch length.

Independent claim 1 — plain-language overview

A cable claim with five structural requirements plus a mathematical limitation:

1. Multiple cable sensors helically wound around a support (the "cable sensor" = a loose-tube-buffered sensing fiber; the support is the central strength member).
2. An outer jacket on and surrounding those sensors.
3. Each cable sensor contains an optical fiber built up as: optical core → cladding → primary coating.
4. A deformable material surrounding the optical fiber, enclosed by an outer tube.
5. Length differential: the optical fiber must be longer than the outer tube by 0.5 to 1.5% ("excess fiber length" / EFL).
6. Design equation: the cable's allowable strain with zero stress on the fiber must satisfy eq. (1), ε = π²dD/p² ≈ 10dD/p², and eq. (2), percent elongation/contraction = ε × 100, where d = fiber-to-tube clearance, D = average pitch diameter of the sensor bundle, p = average pitch length of the helix.

In effect: a small-diameter stranded loose-tube DTS cable where the helix geometry (short pitch, defined clearance) is sized so the fiber can drift radially inside its loose tube and absorb cable strain before any strain reaches the glass.

Dependent claims 2–13 add: an optional tape wrap over the sensors (2); selection of p and D to keep the fiber at zero strain (3) or within ±2% (4); support at the center of the helix (5) and being ductile metal or polymer (6); tape wrap polymer rated >150 °C (7) and being fluoropolymer/perfluoropolymer/copolymer (8); outer jacket being fluoropolymer/perfluoropolymer/copolymer (9); 2 or more sensors (10); specifically 4 sensors (11); deformable material being air (12); outer tube OD 1.5–2.0 mm and ID 0.8–1.2 mm (13).

Independent claim 14 — plain-language overview

A method claim mirroring claim 1: helically winding a plurality of the same cable sensors around a support, then disposing an outer jacket so it surrounds the sensors. It carries the same cable-sensor construction, the same 0.5–1.5% excess fiber length, and the same equations (1) and (2) and variable definitions. Dependent claims 15–16 add placing a tape wrap between the jacket and the sensors (15) and applying the jacket by extrusion (16).

Two things worth flagging

(a) Internal inconsistency on fiber length — likely a prosecution amendment. The abstract, the Summary, and one passage of the Detailed Description all state the fiber is "of equal length to the outer tube." Yet both independent claims require the fiber to be 0.5 to 1.5% longer than the tube, and the description elsewhere says 0.1–2% (with 0.5–1.5% and 0.7–1.4% alternatives). The specification also contains a passage asserting equal length in the context of the neutral position. The prosecution record shows a non-final office action (2019-03-19), a response (2019-08-28), and a notice of allowance (2020-01-03) — consistent with the length limitation having been added during prosecution. I am inferring the amendment; I have not read the file wrapper, so treat the "why" as unverified. Substantively, this written-description tension between "equal length" and "0.5–1.5% longer" is a plausible claim-construction/§112 focal point.

(b) Equation (1) is a validity/reach limitation, not just description. Because both independent claims recite the equation, the "d" and "p" values cannot be used to invalidate a claim while the equation itself is treated as descriptive only. Conversely, a design that achieves the same strain isolation by another relationship would arguably fall outside the claims — a narrowness point relative to the divisional US 10,983,018 B2.

Worked example from the spec (useful for infringement mapping): D = 2.2 mm, tube OD/ID = 1.5/1.0 mm, fiber OD = 0.250 mm → d = 0.75 mm, p = 28.5 mm. Plugging in: ε = 10(0.75)(2.2)/28.5² ≈ 2.0%, matching the stated ±2% allowable cable strain at zero fiber strain, with ~356 N (80 lbf) required for 2% elongation. I verified this arithmetic myself; it was not in the source.

Uncertainty statement: Bibliographic data above comes from the Google Patents and Justia records for this exact number and is internally consistent. The absence of litigation/PTAB/CAFC activity is based on web-visible records only and is not authoritative — a paid PACER/Docket Navigator or USPTO PatentCenter check would be required to state that with confidence.

I'll search litigation-focused sources for this specific patent number.

Initial searches returned only numeric coincidences. Let me run more targeted queries against litigation-specific databases.

Bottom line

No litigation involving US Patent No. 10,648,876 was found in any publicly web-visible source. I found no district court action, no ITC Section 337 investigation, no IPR/PGR/CBM proceeding, and no CAFC appeal naming this patent. The patent has not, so far as public records show, ever been asserted.

That is a negative finding, not a certified clean title. See the method caveats below.

Searches run (all against the literal number only)

I searched the following, deliberately using only the exact identifiers 10648876, US10648876, and 10,648,876, and rejecting near-miss numbers:

False positives I identified and discarded

Every bare-string hit for 10648876 was a numeric coincidence, not the patent:

• UK Companies House / Gazette entry 10648876 — "DECOMMORAMA LTD," a UK company number (https://www.thegazette.co.uk/London/issue/[828910](/patent/828910)/data.pdf).
• Czech public contracts registry — version ID 10648876 for a Prague hospital purchase order (https://smlouvy.gov.cz/smlouva/10648876).
• Russian Minpromtorg registry — entry 10648876 for "Полуботинки специальные кожаные модель 985," a safety-shoe registration.
• Brazilian CTNBio filing — SEI process number 10648876.
• Protonomaly color value 10648876 in a color-conversion PDF.

I did not treat any of these as the patent. The prior section of this analysis flagged the same pattern (including a PubMed ID coincidence), and my searches reproduce it.

Adjacent OFS Fitel enforcement — confirmed to exclude this patent

Because the assignee (OFS Fitel, LLC) is a known litigant, I checked its campaigns specifically. None involves US 10,648,876, and most are chronologically incapable of doing so since they predate the patent's 2017-07-25 priority date:

This matters for the client's freedom-to-operate picture: OFS Fitel is an active enforcer, but the '876 and its divisional (US 10,983,018 B2) appear never to have been deployed.

The divisional

The continuation/divisional US 10,983,018 B2 (app. 16/844,795, issued 2021-04-20) likewise returned no litigation, IPR/PGR, or appeal in any search. Consistent with the parent.

Method caveats — read these before relying on the negative

1. PACER, Docket Navigator, Lex Machina, and USPTO PatentCenter were not directly queryable from this session. The docket aggregators that are web-indexed (CourtListener/RECAP, UniCourt, Docket Alarm, Justia dockets) do not surface this patent. RECAP coverage is incomplete for older and sealed filings, and confidential settlements may never appear.
2. Unified Patents' caselist indexes litigation and PTAB activity but is not exhaustive — it focuses on NPE/PAE-type assertions and may miss ordinary competitor suits.
3. A patent this new (issued 2020-05-12) and this specialized (small-diameter stranded loose-tube DTS cable for offshore oil pipelines) would plausibly see assertion only against a narrow set of cable manufacturers — Halliburton, Schlumberger, TechnipFMC, Prysmian, Nexans, Sterlite, LS Cable, AFL, or similar. Public web search cannot rule out a sealed or arbitration-confidential dispute.
4. No IPR/PGR exists only if none was filed — I searched PTAB-adjacent sources and found none; the absence is consistent but not certified.

Recommendation: before opining on assertion history, run this patent's number through (a) USPTO PatentCenter "Patent Litigation" tab / the USPTO Patent Examination Data System, (b) Docket Navigator or Lex Machina (USP 10648876 field search), (c) PTAB's API for IPR/PGR/DER against 10648876, and (d) PACER for the assignee OFS Fitel as plaintiff. Those four checks convert the finding from "none visible" to "none found."

Note on dates: this task header states the current date as April 26, 2026, while the patent fetch and session date are 2026-09-22. I ran the searches at the later date; the result is unaffected, but the discrepancy is flagged rather than silently corrected.

Uncertainty statement: I am confident that no assertion of US 10,648,876 appears in web-indexed docket or PTAB sources. I am not in a position to represent that the patent has never been litigated, licensed under dispute, or asserted in a confidential or arbitration setting. The list of "adjacent OFS Fitel matters" above is illustrative of the assignee's enforcement history, not a complete docket of that entity.

I'll verify the structured "no proceedings" finding with targeted web searches before reporting.

Let me run a couple more targeted checks for any PTAB/CourtListener activity involving this patent or its owner.

Proceedings overview

Total AIA trial proceedings on file for US 10,648,876: 0. The structured USPTO Open Data Portal "PTAB proceedings on file" block for this patent returns an empty set, and my independent web checks (PTAB/E2E petition documents surfaced by search, PTAB FWD text, CourtListener, and owner-name sweeps for OFS Fitel) surfaced no IPR, PGR, or CBM naming US 10,648,876 — breakdown by status is therefore 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution denials. Bottom line for a defendant: you are facing a virgin claim set. All 16 claims stand exactly as issued on 2020-05-12 — nothing has been canceled, narrowed, or construed by the Board, and no petitioner has burned any art against this patent, so no § 315(e)(2) estoppel exists against anyone.

There is consequently no proceeding to walk claim-by-claim. What follows is the verification record, then the defensive analysis that actually matters.

Verification record (why the count is zero)

Limitation, stated plainly: I could not query PTAB E2E or the ODP API live from this session; the "zero" rests on the structured block plus web-visible corroboration. A paid Docket Navigator / Lex Machina check or a direct PTAB E2E party search (https://ptacts.uspto.gov/ptacts/) would be required to certify it. I found no proceeding numbers, so I have deliberately listed none — inventing them would be worse than an empty list.

Note the cross-reference to the previously generated litigation section: that section also found no public district court, ITC, or CAFC case involving this patent. The two absences are consistent with each other and point the same direction — this is an operating-company patent (OFS Fitel, LLC, a Furukawa Electric subsidiary) that has not been asserted publicly, not a litigation-driven NPE asset. That is a meaningful difference from a patent whose claim set carries an IPR history.

Strategic summary

Canceled vs. sustained vs. untested. Not a single claim of US 10,648,876 has been tested. Claims 1 and 14 (the independent cable and method claims) are untested, and dependent claims 2–13 and 15–16 are equally untested. This matters more than it sounds: there is no FWD construing the two most consequential limitations — the "0.5 to 1.5%" excess-fiber-length requirement and the equation (1)/(2) limitation — and no Board finding on whether the AFL Telecommunications reference (US 2014/0056553 A1, the sole examiner-cited art) teaches the helix-geometry strain-isolation relationship. A defendant gets no free ride from someone else's work, but also inherits no adverse constructions.

Estoppel landscape. There is no § 315(e)(2) estoppel against anyone, because there has been no petitioner and no final written decision. Practically, that means the entire prior-art universe remains available to a first-filing petitioner: every patent and printed publication, in any § 102/§ 103 combination, is unencumbered. The one procedural clock that matters is § 315(b) — an IPR petition is barred if filed more than one year after the petitioner (or a real party in interest or privy) is served with a complaint alleging infringement of this patent. If a demand letter or a complaint has already been served on you, calendar that date now. If only a demand letter has been sent, § 315(b) has not been triggered and you still have a clean runway. A civil action challenging validity does not itself trigger the bar, but service in a counterclaim-served posture can.

Grounds available — and one that is not. Because this patent issued 2020-05-12, it is AIA-first-inventor-to-file (filed 2018-07-20), so IPR is available under § 311 for § 102/§ 103 grounds on patents and printed publications. PGR is time-barred — it must be filed within nine months of grant (§ 321(c)), i.e., by 2021-02-12. That is a real cost for a defendant, because the § 112 written-description problem flagged in the earlier section — the abstract, the Summary, and one Detailed Description passage saying the fiber is "of equal length to the outer tube," versus the claims' "longer than the outer tube by an amount of 0.5 to 1.5%" — cannot be raised in an IPR. It is a district-court invalidity and claim-construction argument only (and a prosecution-history-estoppel lever, given the 2019-03-19 office action → 2019-08-28 response → 2020-01-03 allowance sequence, which is consistent with that limitation having been added by amendment — an inference, not a verified file-wrapper finding). Do not let anyone plan an IPR around § 112; it will be denied as outside § 311(b).

Pattern signals. No repeat-petitioner pattern (no petitioners), no PTAB appeals by the patent owner (no decisions to appeal), and no defensive aggregator in the chain — no Unified Patents, RPX, or similar challenge appears. Independent of litigation posture, the absence of any IPR is itself the signal: well-asserted, high-revenue patents attract challenges within a year or two, and this one has now gone six years since grant with none. Treat the patent as commercially quiet and procedurally fresh — which cuts both ways: no claim is dead, but no claim is preserved by anyone's victory either.

Recommended next steps

1. Confirm the zero yourself before relying on it. Run a PTAB E2E party/patent search at https://ptacts.uspto.gov/ptacts/ and check the ODP API directly. If a recently filed petition exists that the ODP ingest missed, it would appear there first. If you are already served, immediately calendar the § 315(b) one-year bar.
2. If you intend to invalidate, build the IPR around the equation and the pitch parameters, not § 112. The claims' core novelty is arguably the numerical relationship ε = π²dD/p² (≈ 10dD/p²) tied to a short-pitch helix. That is a printed-publication/§ 103 target: look for prior DTS cable art disclosing small-pitch helically stranded loose-tube construction and the fiber-clearance geometry, and for art disclosing the 0.5–1.5% excess fiber length. The examiner only cited one reference (US 2014/0056553 A1, AFL Telecommunications), which is a thin search record.
3. Exploit the written-description inconsistency in district court and at the Markman stage. The "equal length" vs. "0.5 to 1.5% longer" tension is the cleanest § 112 / claim-construction hook on this patent, and it is unavailable at the PTAB. Pair it with a prosecution-history review of the 2019 amendment to assess prosecution history estoppel on the length limitation.
4. Mind the sibling. The divisional US 10,983,018 B2 (from app. 16/844,795, issued 2021-04-20) is a separate patent with its own claims and its own § 315(b) clock. Clearing US 10,648,876 does not clear the family; freedom-to-operate work should cover both.
5. If you are the patent owner or a licensee, the flip side: with no PTAB history, the claims are at full breadth and untested, and the DTS operating claims (temperature range −45 °C to +125 °C, ±2% strain tolerance) are still intact to market. The earlier "narrowness point" — that a competitor achieving the same strain isolation by a different geometric relationship may fall outside the equation-limited claims — remains the principal assertion risk.

Uncertainty statement: The empty proceedings list is drawn from the structured ODP block and corroborated by web search only. I found no proceeding number, FWD, panel, or appeal to report, and I have not created any. No litigation or PTAB activity involving US 10,648,876 or its divisional was located on publicly visible records as of 2026-09-22 — that is a limitation of open-source checking, not a certification of non-assertion.

I'll verify the assignment record and cross-reference ownership before writing the analysis.

I verified the ownership chain against Google Patents' legal-events record, the Furukawa corporate filings, and OFS's own litigation history. Here is the analysis.

Inventors

Pattern check — no red flag. All four are OFS Fitel employees-inventors, and the chain of title is a straight employee→employer assignment (documented below), not a post-hoc purchase. I found no public evidence that any of the four departed OFS within 12 months of the 2017-07-25 priority date — but note that absence of such evidence is a scope limitation, not an affirmative finding; inventor-employment continuity is not systematically tracked in free sources. The relevant point for your NPE screen is that the patent never left the operating company, so an inventor-departure fire-sale could not have occurred regardless.

Original assignee

OFS Fitel, LLC — Norcross, Georgia (2000 Northeast Expressway, Norcross, GA 30071). Named as original and current assignee on the face of US 10,648,876.

• Primary business: operating company. Designs and manufactures optical fiber, fiber-optic cable, connectivity/FTTx products, and specialty photonics — explicitly including oil-and-gas distributed temperature sensing (DTS) fibers and cables marketed under names like GeoSil® and AcoustiSens® (the exact commercial field of this patent). It is not a licensing vehicle.
• Ownership: wholly owned subsidiary of Furukawa Electric Co., Ltd. (Tokyo; founded 1884). OFS traces to the 2001 purchase of Lucent's U.S. optical fiber business. (Furukawa Electric release, 2024-07-11; OFS company statement)
• Current status: operating. In 2024–2025 Furukawa reorganized its global optical fiber/cable business into a holding company (Lightera Holding G.K.) and a new brand, Lightera™, launched 2025-04-01. OFS Fitel, LLC (US) is being folded in as "Lightera, LLC (US)." This is a parent-level internal reorg, not a transfer to an NPE. (Furukawa release; AusOptic/Lightera summary)
• Product/assertion posture: OFS is a practicing entity that has historically asserted its patents against actual competitors — e.g., OFS Fitel LLC v. Sterlite Optical Technologies, 1:02-cv-02149 (N.D. Ga. 2002); suits against Nufern and YOFC (2005); an Alcatel action in N.D. Cal. This is classic operating-company enforcement, not NPE behavior.

Assignment timeline

The Google Patents legal-events record for this patent shows exactly one assignment event (code AS) and nothing after grant. Reconstructing it:

• 2018-07-24 → 2018-08-09 (executed) / recorded 2018-09-25 — Reel 046963 / Frame 0122
  • Conveyance: Assignment (of assignors' interest)
  • Assignor: DYER, ROBERT S; LI, JIE; PACINI, JOHN E; VIOLETTE, BRIAN
  • Assignee: OFS FITEL, LLC (Georgia)
  • Correspondent: Not exposed by the sources available to me. The Google Patents legal-events docket text gives only ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:DYER, ROBERT S;LI, JIE;PACINI, JOHN E;AND OTHERS;SIGNING DATES FROM 20180724 TO 20180809;REEL/FRAME:046963/0122 — the correspondent-of-record field is a USPTO Assignment Center/PEDS field I could not query from this session. For a large operating assignee this is ordinarily the company's own IP department (OFS legal, Norcross GA) or its regular outside patent counsel, not a repeat NPE-filing attorney — but I am flagging this as unverified rather than asserting it.
  • Context: original employee-inventor → employer assignment. Secures title for the applicant before grant. No acquisition, no fire-sale.

No other recorded assignments. There is no second reel/frame, no security agreement, no merger, no change of name, and no transfer to any licensing entity. The "subsequent events" in the record are prosecutorial/administrative, not conveyances:

• 2020-04-09 — divisional US 16/844,795 filed (slated to issue as US 10,983,018 B2 on 2021-04-20). This is a continuation of the family by the same owner, not an assignment.
• 2020-05-12 — patent granted.
• 2023-11-13 — 4th-year maintenance fee paid by a large entity (M1551). The original assignee is still paying to keep the patent alive, which is affirmative evidence it still owns it.

I could not open the USPTO Assignment Center page directly from this session, so the "single assignment" conclusion rests on the Google Patents legal-events mirror; it is consistent with, but not a substitute for, a live Assignment Center query.

Timeline diagram

timeline
    title Ownership of US 10648876
    2017 : Provisional filed by OFS inventors
    2018 : Filed as US application 16 040 950
         : Inventors assign to OFS Fitel LLC
    2019 : Pre-grant publication
    2020 : Patent granted to OFS Fitel LLC
         : Divisional filed by same owner
    2021 : Divisional issues as US 10983018
    2023 : Fourth year maintenance fee paid
    2025 : OFS folded under Lightera brand

NPE / troll-pattern signals

1. Shell-entity transfer — NOT PRESENT. No assignment to any "IP / Holdings / Licensing / Ventures" entity exists. The only recorded conveyance (Reel 046963/0122, 2018-09-25) runs to the operating manufacturer, in the opposite direction from an NPE setup.

2. Known asserter in the chain — NOT PRESENT. Neither OFS Fitel, LLC nor Furukawa Electric appears on the enumerated NPE lists (Acacia, Marathon, IV, IPNav, Wi-LAN, Conversant/Mosaid, Vringo, Pendrell, Round Rock, Spangenberg entities, etc.). OFS is the target of no such list; it is a Fortune-scale fiber-optic manufacturer.

3. Repeat correspondent across the chain — NOT PRESENT (and not detectable). With a single assignment record, there is no recurrence to detect, and a lone correspondent appearance is in any event not a finding under your rubric. The correspondent field itself was not retrievable here (see timeline caveat).

4. Cascading transfers — NOT PRESENT. No chained-LLC transfers; nothing within 24 months; no intermediate assignees at all.

5. Pre-litigation transfer — NOT PRESENT. There is no infringement suit naming US 10,648,876 (confirmed earlier in this analysis: no district court, ITC, PTAB, or CAFC matter is web-visible against this number). There is therefore no 6-month pre-suit assignment.

6. Bankruptcy fire-sale — NOT PRESENT. OFS/Furukawa have not filed bankruptcy; the 2024 restructuring is a solvent intra-group reorganization under a Japanese parent. No Chapter 7/11 sale.

7. Privateering — NOT PRESENT. No transfer to a third-party asserter acting for OFS. OFS litigates in its own name.

8. Defensive aggregator — NOT PRESENT. The chain does not terminate at RPX, AST, LOT, Unified Patents, or OIN.

Verdict

Insufficient data (no records, or only the original assignment).

The choice of this option is dictated by the constraint, not by ambiguity about ownership: the record contains only the original assignment — Reel 046963/0122, recorded 2018-09-25 — from the four named inventors to OFS Fitel, LLC, with no post-issuance conveyance of any kind. That is an explicitly benign form of "insufficient data": the patent simply was never transferred. It is not in an NPE chain, not in a defensive-aggregator chain, and not subject to any current assertion. The assignee remains the original operating manufacturer (OFS Fitel, LLC, a Furukawa Electric subsidiary, now being rebranded under Lightera), which continues to pay maintenance fees (2023-11-13) and whose corporate parent has never filed for bankruptcy. No signal in the enumerated set is present.

Verification links: USPTO Assignment Center — https://assignmentcenter.uspto.gov/ ; legacy search — https://assignment.uspto.gov/patent/index.html (query patent number 10648876; I could not execute the query from this session, so re-run it to confirm the single-record finding). Family/legal events: https://patents.google.com/patent/US10648876/en .

I'll ground this in live searches before writing anything.

Good grounding so far. Let me pin down the cited reference and check for any additional citations on the face of the patent.

1. Search scope and method caveat (read this first)

I ran targeted queries for the literal string 10648876 and the identifiers US10648876 / US10648876B2, and separately for the patent's citation list, via web-accessible mirrors of the USPTO record (Google Patents, Justia, FreePatentsOnline, PatentImages full-text PDFs). I could not open the USPTO's native PatentCenter/Patent Application Information Retrieval or the file-wrapper (IFW) image set from this session, so the citation list below is the one printed on the face of the granted patent as mirrored, not a certified reproduction of every paper in the file wrapper (e.g., unprinted IDS submissions, Form 892/1449 lists, or references cited only in a terminal-disclaimer-era IDS).

Disambiguation warning — directly responsive to your "do not return results for similar numbers" instruction. One of my searches surfaced an international search report (for PCT/US2018/029650, published as WO2018200874A1) that categorizes US 6 106 476 A (Corl, Paul D., 2000-08-22) as an X-reference. The string 106476 is a different patent number (US 6,106,476 — a 2000 intravascular-device patent), and the OCR of 10648876 can also collapse to 106476. I did not treat US 6,106,476 as a citation to the patent at issue, and it is not part of the 10648876 record. Likewise, the earlier-flagged coincidence hits (a PubMed ID 10648876, a Czech contract-registry ID, a UK company number) are not this patent.

2. The citation(s) on the face of US 10,648,876 B2

The 10648876 record shows exactly one patent document cited and considered:

Important structural point for the § 102 analysis: US 2014/0056553 A1 is the pre-grant publication of application 13/877,018, which is the same application that issued as US 9,557,231 B2. The two share a specification. For anticipation purposes the operative disclosure is what the published document showed as of 2014-02-27; the granted claims of US 9,557,231 B2 are relevant only insofar as they reflect subject matter that was also in the published description.

3. Brief description of US 2014/0056553 A1

Grounded in the published text:

• Field/purpose: sensing cables for detecting external pressure, strain, temperature and acoustics, expressly for oil-and-gas downhole, logging and data-logging use; the specification notes BOTDR/BOTDA-type distributed sensing and the difficulty of separating pressure from strain. (https://www.freepatentsonline.com/y2014/0056553.html)
• Core structures disclosed: (a) a slotted core, a one-piece integral member with a plurality of channels on its perimeter extending along the length of the core — and the channels "may extend along the length of the slotted core in an arrangement parallel to a longitudinal axis of the slotted core, or may extend along the length of the slotted core in a helical arrangement"; (b) a stranded wire core of coupled wires, and (c) a cable core structure with holes/slits through a protective member.
• Fiber-in-tube architecture: an exposed component (optical fiber or wire) sits in a channel; an unexposed component (optical fiber or wire) is encased by a protective member — and the reference states "the first protective member and the second protective member may be protective tubes."
• Stranding/central member: "the first protective member and the second protective member may be stranded together"; "the second protective member may be stranded around a central part of the first protective member"; and "the sensing cable may also include a central strength member disposed along the length of the cable, and the cable core structure may be stranded around a central part of the central strength member."
• Outer layer: "The sensing cable may further include a protective layer which surrounds the cable core structure … a protective tube structure or a plurality of wires."
• Stress relief / clearance idea: the reference describes the exposed component being shielded by wires, and (in the shared specification) a "small gap between each of the wires and the exposed component. This gap will protect the exposed component from the external stress," while still letting it sense pressure; and it states that the stranded core "can be helixed to allow for increased strain window in components … and improve coupling of components," and that the design "can reduce creep and core slippage."
• Materials: protective members/layers may be PVC, PE, PFA, PVDF, TEFZEL, TEFLON, PTFE, PBT, PP, etc.; the sensor cable may be used as oil well cables, downhole cables, data logging cables.

What the reference does not state (as far as the retrieved text shows): it does not state a quantitative excess fiber length (fiber longer than its tube by 0.5–1.5%), it does not set out the helix pitch/clearance design equation ε = π²dD/p² ≈ 10dD/p², and I did not find any disclosed OD/ID dimensional ranges for the protective tubes in the portion of text I could retrieve. I flag those as "not found in the retrieved text," not as affirmative absences from the document.

4. § 102 analysis — which claim(s) US 2014/0056553 A1 potentially anticipates

Controlling law frame. The '876 patent's earliest effective filing date is 2017-07-25 (provisional 62/536,575), so the AIA version of § 102 governs. US 2014/0056553 A1 published 2014-02-27, which is more than three years before the effective filing date. It is therefore § 102(a)(1) prior art ("described in a printed publication") and, independently, § 102(a)(2) prior art as a U.S. application publication effectively filed 2011-09-30. Because the reference is AFL's and the '876 is OFS Fitel's, there is no § 102(b)(2)(C)/102(b)(1)(A) common-ownership or inventor-origination exception available. It also sits well outside any one-year grace period, so even under the pre-AIA rubric it would be § 102(b) art.

Element-by-element against independent claim 1:

Claim-by-claim verdict:

• Claims 1 and 14 (independent): NOT anticipated on the record as retrieved. Two limitations are unmet — the 0.5–1.5% excess fiber length and the eq. (1)/(2) pitch-clearance limitation. Both are express claim limitations, so a § 102 rejection cannot be sustained against either independent claim on this reference alone.
• Claims 2–13: NOT anticipated — every dependent claim incorporates all limitations of claim 1, including the two unmet ones. That said, the reference is most substantively close to:
  • claim 5 (support at the center of the helical winding) — directly taught ("stranded around a central part of the central strength member");
  • claim 6 (support = ductile metal or polymer) — consistent with the AFL disclosure of metallic wire cores and polymer protective layers, though I have not verified a literal "ductile metal or polymer" statement;
  • claim 10 (2 or more sensors) and claim 11 (4 sensors) — the AFL disclosure contemplates multiple components/channels; a literal "4" statement is not verified;
  • claim 12 (deformable material = air) — the "gap" teaching is the closest support;
  • claim 2 (tape wrap) and claim 13 (tube OD 1.5–2.0 mm / ID 0.8–1.2 mm) — not found in the retrieved text.
• Claims 15 and 16: NOT anticipated. Claim 15 incorporates claim 14; claim 16 ("extrusion" jacket application) is a manufacturing limitation for which I found no counterpart in the reference.

Net characterization: the examiner's citation of US 2014/0056553 A1 is best understood as § 103 / general-relevance art (loose-tube, helically stranded, centrally-supported sensing cable with a protective outer layer), not § 102 anticipatory art. This is consistent with the '876 having issued with both independent claims requiring the two extra limitations — and, more importantly, consistent with the earlier-flagged indication that the fiber-length limitation was likely added by amendment during the 2019-03-19 office action → 2019-08-28 response → 2020-01-03 allowance sequence. That amendment is precisely the kind of change that converts near-anticipatory art into § 103 art.

5. Additional relevant prior art — NOT on the face of US 10,648,876 (flagged separately)

You asked specifically about the patent citations for 10648876; the authoritative answer is the single reference in § 2. The following are candidate references I encountered during the search but which do not appear on the 10648876 citation list, offered only as a landscape note, with the verification limits stated. None of these should be reported as "cited against US 10,648,876" unless a file-wrapper check confirms it.

6. What would change this answer

1. A file-wrapper (IFW) pull would show the complete IDS/892 citation list. The Google Patents and Justia faces show one citation apiece, but IDS-submitted and non-examiner-cited references (particularly NPL and foreign documents) are frequently not printed on the front page of a granted U.S. patent. Treat "one citation" as the face-of-patent count, not the file-wrapper count.
2. A literal text comparison against the 2014-02-27 published document (not the later US 9,557,231 B2 text) is required for a defensible § 102 position, since a national-stage publication and the granted patent can diverge in the specification if amendments were made.
3. The § 112/claim-construction tension flagged in the previously generated section (abstract, Summary and parts of the Detailed Description saying the fiber is "of equal length to the outer tube" while claims 1 and 14 require the fiber to be 0.5–1.5% longer) interacts with this art directly: if the "0.5–1.5% longer" limitation were ever read out of the claims, US 2014/0056553 A1's disclosure becomes materially closer to the independent claims — the equation limitation would then be the principal distinguishing feature.

Uncertainty statement: the citation identification (one examiner-cited reference: US 2014/0056553 A1) is grounded in the 10648876 record itself and is internally consistent across Google Patents, Justia and FreePatentsOnline. The § 102 mapping rests on the retrieved text of that reference; I explicitly did not locate an excess-fiber-length disclosure or the pitch/clearance equation in it, but I cannot rule out that such content exists in portions of the document not returned by my searches. No litigation, IPR, or CAFC activity involving US 10,648,876 was found in web-visible sources — that remains a limitation of this search, not a finding of non-assertion.

I'll ground this in the actual prior-art references tied to this patent before analyzing. Let me pull the content of the examiner-cited reference and the closest "similar documents."

Good — that surfaced the key physics reference. Let me verify a few more of the page's prior-art entries.

Let me check the remaining page-listed references, and whether the helix-length equation appears in any of them.

Obviousness Analysis — US 10,648,876 B2 under 35 U.S.C. § 103

Scope note. The patent has an effective filing date of 2017-07-25 (provisional 62/536,575) and was filed 2018-07-20, so it is governed by the AIA versions of §§ 102/103. Every reference below must therefore qualify as prior art with a date before 2017-07-25. Date note: the task header says 2026-04-26 while the session/fetch date is 2026-09-22; the earlier section flagged this and I do not repeat it beyond noting the analysis is unaffected.

1. The prior art, and exactly where each reference came from

The page you told me to work from has three prior-art-bearing sections: Citations (1) (examiner-cited), Similar Documents, and Families Citing this family. The third is not prior art — every entry post-dates 2017-07-25 (e.g., EP 3 816 686 A3, KR 102833549 B1, JP 6851102 B1, US 2022/0221676 A1, US 2023/0251444 A1, CN 115262862 B). I exclude them.

I flag that last row explicitly: US 4,695,128 is not one of the references listed in this patent's Prior Art pages. It surfaced from my own search. It is nonetheless the single most useful reference for this analysis, so I present it as supplemental art and label it as such wherever it does the work. (Note the near-miss: the page lists US 4,696,542 A, "Armored optical fiber cable," a different patent I did not verify.)

2. Claim 1, element by element

Claim 1 requires: (a) a plurality of cable sensors helically wound around a support; (b) an outer jacket on/surrounding them; (c) each sensor = optical fiber with core → cladding → primary coating; (d) a deformable material surrounding the fiber; (e) an outer tube surrounding the deformable material; (f) the fiber 0.5–1.5% longer than the tube; (g) the allowable strain "determined by" eqs. (1) and (2), ε = π²dD/p² ≈ 10dD/p².

The equation is ordinary algebra over the '128 geometry — not a patentable contribution

Equation (1) is exactly the fractional difference between the helix path length of a fiber pinned at the tube's outer wall (helix diameter D + d/2) and at its inner wall (helix diameter D − d/2):

ε = [√(π²(D+d/2)² + p²) − √(π²(D−d/2)² + p²)] / p

A first-order binomial expansion (legitimate here because π²D² ≪ p²) collapses this to ε ≈ π²dD/p² ≈ 10dD/p². I verified both the exact and approximate forms against the spec's own Example (D = 2.2 mm, d = 0.75 mm, p = 28.5 mm → 2.03%, matching the stated ±2%). Anyone of skill given the '128 helix equation and the '876's own geometry obtains eq. (1) in one algebraic step. The specification itself presents "= 10dD/p²" as a simplification, not an invention.

The strongest fact I found: the prior art already satisfies eq. (1) numerically

Running the '876 equation on US 9,529,169's own disclosed embodiment — free space d = 0.66 mm (0.92 mm tube ID − 0.26 mm fiber OD, matching the '876's definition of d exactly), lay length 70 mm on the second cable whose stranding layer gives a helix diameter D ≈ 3.6 mm — yields ε = 10(0.66)(3.6)/70² ≈ 0.49%, which is the '169 patent's stated strain-free window of ~0.49%. The first embodiment (lay 50 mm, D ≈ 1.6–1.9 mm) reproduces its stated 0.43% within roughly 15% (D is not explicitly stated there; I inferred it from component dimensions). In other words, the claimed equation is a restatement of the behavior the earlier cable already had. That is a powerful inherency argument: a cable meeting the geometry limitation necessarily meets the equation limitation.

3. Grounds of rejection

Ground A — Herbst '778 in view of Herbst '169, further in view of Siecor '128 (primary)

US 2011/0058778 supplies (a) through (f): a plurality of loose-tube sensors, excess fiber length, a central strength element, stranding, an outer jacket, radial fiber migration, a strain-free window of 0.1–4% (preferably 1–2%), and pipeline BOTDR monitoring. US 9,529,169 supplies the coil geometry — a helically wound tube at a stated lay length/pitch, an explicit quantitative statement that "the amount of strain free window depends on the lay length or pitch of the tube and the excess length of the optical fiber," and a demonstration of exactly the "small cable, strain-free fiber for accurate Brillouin temperature" problem the '876 addresses. US 4,695,128 supplies the helix-length relationship from which eq. (1) follows and confirms the radial-migration mechanism.

Motivation: the '169 patent states the design rule the '876 claims — you choose pitch and excess length to hit a target strain-free window. The '778 application says the same ("the layout of the gel-filled tubes, size of the tube, wall thickness, number of fibers, center member diameter and the starting excess fiber length… all play a role in the determination of the strain free window"). Two references that each tell the artisan "size p, D and d to set the window" are combinable on their face. There is no teaching away: the '876's fiber-moves-outward-on-contraction / inward-on-elongation behavior is the same behavior the '128 patent describes.

Ground B — AFL '553 in view of Herbst '169/'778

The examiner's sole citation, US 2014/0056553, teaches a sensing cable with exposed and protected sensing fibers, a protective member encasing the unexposed component, a central strength member, a surrounding protective layer, and — critically — helixing "to allow for increased strain window in components," with a gap between the armor wires and the component that "will protect the exposed component from the external stress." That is the same structural proposition (clearance gap ⇒ protected, strain-isolated fiber) in the same field (oil-and-gas downhole/distributed sensing). Combine with '778 (excess fiber length, stranding about a central element, outer jacket, Brillouin pipeline monitoring) and '169 (pitch/lay-length control of the window) and claim 1 is met.

Note that this reference is AFL art aimed at the same problem, which independently corroborates that the field was converging on the '876 solution. The claim's only remaining distinctions are the numeric EFL range and the equation — both addressed above.

Ground C — '169 or '778 in view of Draka '8,929,701

For the materials-dependent dependent claims, US 8,929,701 teaches a loose-tube cable with a fluoropolymer protective tube (claim 5), an optical fiber and tube "capable of operating at temperatures of at least about 200 °C" (claim 1), a longitudinal strength member, and an outer jacket — directly addressing the high-temperature/harsh-environment requirement the '876 recites as its advantage.

4. Motivation to combine (KSR factors)

1. Same field, same problem, same art. All primary references address strain-isolated optical fiber sensing in oil/gas (DTS/BOTD(A/R)), where the fiber must remain strain-free for accurate temperature measurement. KSR permits combination where references are "from the same field of endeavor."
2. Common inventorship / common assignee. Brian Herbst is the named inventor of US 2011/0058778 and of US 9,529,169 (AFL Telecommunications LLC). Combining one's own earlier strain-free-fiber cable with one's own earlier helically-wound logging cable is not merely suggested — it is the natural next step. (I did not verify the assignee of the '778 application; the inventor overlap is confirmed.)
3. Express design rule. The '169 patent: "[t]he amount of strain free window depends on the lay length or pitch of the tube and the excess length of the optical fiber in the tube." The '876 claims precisely the relationship the '169 patent tells the artisan to exploit. This is the strongest possible "motivation" — a statement of the operative variable.
4. Known mathematical relationship. The helix length equation (and hence eq. (1)) was in the art since at least 1987 ('128). Using a known formula to predict the performance of a known structure is routine.
5. Predictable results / optimization. Nothing in the claims produces an unexpected result; selecting p, D and d for a target window is optimization of a known parameter space (KSR; In re Aller).
6. No teaching away. No reference disparages radial fiber movement, short pitch, or excess fiber length. '778 and '128 affirmatively embrace radial migration toward the cable center under tension — the same phenomenon described in the '876 FIG. 3.

5. Dependent claims 2–13, 15–16

6. Where the patentee has traction (and how strong it is)

Strongest patentee arguments:

1. The 0.5–1.5% excess-fiber-length range as a "critical" limitation. This is the element added during prosecution (consistent with the earlier section's inference from the 2019-03-19 office action → 2019-08-28 response → 2020-01-03 allowance). But there is no data in the specification showing criticality of 0.5–1.5% versus the disclosed alternatives (0.1–2%, 0.7–1.4%). Under In re Aller, a recited range without demonstrated criticality is an obvious optimization. This argument is weak unless the patentee can produce post-filing evidence.
2. Internal inconsistency — a real vulnerability. The abstract, Summary, and one passage say the fiber is "of equal length to the outer tube," while claims 1 and 14 require it to be 0.5–1.5% longer. This is a § 112 written-description/definiteness problem (the earlier section flagged it; I agree it is a plausible § 112 focal point), and it undercuts the claim's causal story: if a cable carries 0.5–1.5% excess fiber length, the strain-free window is the EFL contribution plus the radial-migration contribution — yet eq. (1) computes only the radial contribution. So the claim simultaneously requires two features that, as claimed, are arithmetically inconsistent. That is a § 112(a)/(b) attack and, in the alternative, an argument that the "determined by" limitation is indefinite.
3. Inherency cuts against, not for, the patentee. Because eq. (1) is exact for the geometry, a cable practicing the geometry inherently satisfies it. That makes the equation limitation nearly free to meet in an infringement case and nearly impossible to rely on for validity.

Weak patentee arguments: "the field did not combine loose-tube cable art with downhole sensing art" — but '778, '169, '553 and '701 all sit in precisely that intersection. Any commercial-success or long-felt-need argument must be tied by nexus to the claimed 0.5–1.5% EFL and the equation, since that (together with the sub-5 mm diameter) is the only arguable novelty.

7. Non-§103 theories worth noting alongside

• § 101 (brief). The claims arguably make the mathematical relationship the point of novelty. Because the equation is integrated into a manufactured cable, Alice step 1 is likely satisfied and the claim is probably eligible — but a § 101 challenge directed at the "determined by" clause is not frivolous and parallels the § 103 math-limitation point.
• § 112 (stronger than § 101 here). The "equal length" vs. "0.5–1.5% longer" contradiction; the unproven criticality of the range; the questionable premise that the equation governs a cable that also has positive EFL.

8. What I could not verify — do not rely on these

1. US 4,695,128 is not in this patent's listed prior art. I verified its existence, date, owner, claims and the helix-equation passage from the patent PDF and Justia/Google Patents records — but if you need a rejection grounded only on the references the examiner/Google lists, Grounds A and B must be reformulated around US 4,696,542 and the unverified Similar Documents, which I did not read.
2. Priority dates for US 2018/0329095 A1, US 10,739,169 B2 and CA 2 924 656 A1 are unverified. Two of them (the '095 publication and the '169 patent) post-date 2017-07-25 on publication/grant and can only be §102(a)(2) art if their effective filing dates qualify. Do not use them until checked in PatentCenter.
3. No file-wrapper inspection. My characterization of the 0.5–1.5% limitation as a prosecution amendment is an inference from the office-action/allowance dates. I did not read the amendment.
4. I did not verify the contents of US 4,696,542, US 6,404,961, US 2004/0258373, US 6,466,716, the Japanese references, DK 2674738 T3, or US 9,557,977. Several of these (particularly US 6,466,716 B1, "Optical fiber having a Bragg grating in a wrap that resists temperature-induced changes in length," and US 2004/0258373 A1, "Monitoring cable") look promising for claims 3–4 and should be read before finalizing.
5. My numerical reproduction of the '169 strain-free windows assumes helix diameters inferred from the '169 component dimensions, since that patent does not state D directly. The 70 mm-lay case matched to within ~1.4%; the 50 mm case matched to within ~15%. Treat the derivation as a strong but not exact confirmation.

Bottom line: the structural combination claimed in claim 1 appears obvious over US 2011/0058778 (Herbst) in view of US 9,529,169 (AFL/Herbst) and US 4,695,128 (Siecor) — and, on the examiner's own citation, over US 2014/0056553 (AFL) combined with the same teachings. The equation limitation is the algebraic consequence of the helix geometry already in the art, and the claimed 0.5–1.5% excess fiber length is an unproven, overlap-range optimization that is moreover internally inconsistent with the specification's "equal length" disclosure. The dependent claims fall with the independent claims, with claims 12 and 13 having the cleanest single-reference mappings ('169).