The ranked dataset covers 100 assignees, with the leading filer holding 435 records against 144 for the fifth-ranked assignee and 66 for the tenth. That is a steep concentration at the very top, but the top five combined still account for only 30.6% of all 4,744 records, so the majority of the field is held by a long tail of smaller filers. Anyone doing freedom-to-operate work should check both the leader's portfolio and the long tail, since narrow claims from smaller filers can still block specific implementations.

Filings rose from 287 in 2017 to a peak of 648 in 2022, then fell to 353 by 2024, a -37% change across that three-year span. Because patent publication typically lags the actual filing date by around 18 months, the lower counts shown for 2025 and 2026 are incomplete rather than evidence of a real slowdown. The safest read is that filing activity has passed its 2022 peak but the current trajectory will not be clear until those later years finish publishing.

Just over half of all 4,744 records, 50.9%, carry a G01S classification for radar, sonar and positioning, reflecting how central lidar and ranging applications have become to this field. Semiconductor-device claims under H01L follow at 29.3%, and pictorial-communication claims under H04N sit at 17.0%. Since a single record can carry several IPC codes, these shares overlap rather than summing to 100%, so they describe where claim density sits, not a clean split of the field.

US11982566B2, granted to Yeda Research & Development Co. Ltd. in 2024, claims a system that ties a single-chip SPAD array positioned at an optical system's focal plane to a timing circuit used specifically for photon-correlation measurement. That combination — single-chip array, focal-plane placement and correlation-focused timing — is the specific thing blocked, not SPAD arrays or timing circuits generally. Work that uses a SPAD array for straightforward ranging or imaging without photon-correlation measurement, or that uses a multi-chip rather than single-chip array, sits outside this particular claim scope, though a full clearance would need claim-by-claim review.

Relative to the dense coverage in ranging (G01S) and core semiconductor device claims (H01L), areas like afterpulsing-suppression quenching circuit design, fill-factor and microlens co-design, and time-to-digital converter integration at the array level show comparatively thinner claim density. The smaller overlap classes, such as photovoltaic-adjacent SPAD structures and photon-counting applications in nuclear or X-radiation measurement, also point to less-crowded adjacent branches. These are starting points for a novelty search, not guarantees of open space, since thin coverage in an IPC subclass can still mean dense coverage on a specific claim element.