Ultra-Wide, No-Distortion Optics <BR>for Drone and UAS Gimbal ISR Payloads

An EO/IR dual-sensor gimbal payload must satisfy two separate wavelength requirements at once, each falling to a different sensor. The electro-optical (EO) channel covers the visible band and extends into the near-infrared, typically spanning roughly 400–900 nm [29] — closely matching the 435–940 nm band Theia’s lens line is corrected across, discussed below. The IR channel, by contrast, is a separate thermal-imaging path operating in long-wave infrared (LWIR), 8–14 micron [30]. A mid-wave infrared (MWIR, 3–5 micron) channel is available as a higher-performance alternative to LWIR, but MWIR detectors typically require cryogenic cooling. The two subsections below cover the pieces of this wavelength budget that bear directly on lens selection: the optical correction a lens needs to hold focus across both the visible and NIR portions of the EO channel, and the practical reach of onboard NIR illumination at night.

Why Does NIR Correction Matter?

A lens designed only for visible wavelengths experiences focus shift when switching to NIR, because different wavelengths focus at different optical positions. A properly wavelength-corrected lens holds focus without a mechanical refocus step when a gimbal camera switches between color-day and monochrome-IR-night modes, useful for a lens sealed inside a gimbal ball with no in-flight manual-adjustment capability. In ISR missions, this can enable a single visible/NIR-corrected lens to support Day/Night EO/IR imaging, rather than requiring separate optics for daytime visible imaging and nighttime NIR imaging.

What Is the Practical Range of Onboard Illumination?

Onboard drone illuminators are a close/medium-range tool, not a substitute for passive thermal imaging at longer standoff: illumination intensity falls off with the inverse square of distance [32], so longer-range detection is handled by passive thermal (LWIR, 8–14 micron) imaging rather than active illumination [30].

Ultra-wide lenses for this role are typically corrected across a visible-through-NIR band (435–940nm), though coverage varies by model:

The Requirement

For a lens mounted to an aircraft gimbal, the mission need is simple to state and hard to meet: hold image quality through sustained shock and vibration, with no drift in focus, no element shift, and no mechanical failure.

MIL-STD-810 is the U.S. Department of Defense's environmental engineering standard for proving that equipment can survive the shock, vibration, temperature, and other stresses it will face over its service life.

It isn't a single pass/fail spec. It's a library of test methods — Method 514 for vibration, Method 516 for shock, and Methods 501/502/503 for temperature and thermal shock, among others — that each program tailors to its own platform and mission profile. The reference levels drawn from these methods are commonly cited as baseline expectations for avionics/vetronics equipment [22].

How Theia's Lenses Measure Up

Theia lenses have demonstrated performance above the commonly cited MIL-STD-810 avionics/vetronics reference levels (see Figure 5)..

Testing of Theia’s ultra-wide lenses was run against a customer statement-of-work specification, not a formal MIL-STD-810 certification plan [33]. But both the shock and vibration tests were conducted at magnitudes above the standard's commonly cited functional-shock and general aircraft-equipment vibration reference levels. Remaining fully functional at those magnitudes indicates Theia's lenses surpass the shock/vibration performance typically expected of MIL-STD-810-referenced avionics equipment.

Two Configurations, Further Ruggedized

The MY125M-E and MY23F go beyond the mechanical design shared across the rest of the line: • MY125M-E — reinforced C-mount housing; focus and iris rings locked with a thumbscrew-and-setscrew mechanism to prevent element and ring shift under shock/vibration. Weight penalty is minimal: 103 g vs. 99 g for the standard MY125M. • MY23F — elements fixed directly within a metal housing rather than a standard barrel; focus ring locked with three setscrews; C-mount/M12 mount integrated directly into the housing rather than attached as a separate ring, eliminating the mount-separation failure mode that threaded, non-integrated mounts can suffer under impact.

Validated Beyond the Test Bench

The MY23F's construction has also held up outside the formal shock and vibration test program: in Theia's vehicle crash-test case study, it held focus and showed zero failures across more than 45 automotive impact tests. The MY125 has been used in Aeronautics training and NASA drone applications without reported failure.

Bottom line: every configuration in the line has documented shock/vibration test data, two are purpose-built for the harshest environments, and the toughest of those has real-world crash-test evidence to back it up.

What About Temperature?

MIL-STD-810 addresses thermal stress through Method 501.7 (High Temperature), Method 502.7 (Low Temperature), and Method 503.7 (Temperature Shock), each tailored to a program’s climatic category [22]. As with shock and vibration, formal temperature qualification is performed at the system level by the gimbal or platform integrator. At the lens level, the relevant figure is the operating temperature range for equipment mechanical function and imaging performance. Again, Theia’s ultra-wide, no-distortion lenses operate reliably from -20°C to +60°C.

This range spans the ambient conditions of the - environmental engineering standard for proving that equipment can survive the shock, vibration, temperature, and other stresses it will face over its service life per U.S. Department of Defense's MIL-STD-810 standard for Basic Hot (A2, 30 to 43°C) and Hot Dry (A1, 32 to 49°C) climatic categories, however on the cold side Theia’s lenses only meet the Mild Cold (C0, -19 to -6°C) designation.

Since the environmental qualification is determined at system level, as discussed above, temperatures beyond the lens's own −20°C to +60°C operating range are where platform-level mitigation applies. On the cold side that means the harsher MIL-STD-810 categories introduced above — Basic Cold (C1), Cold (C2), and Severe Cold (C3) beyond the Mild Cold (C0) edge the lens's −20°C floor reaches. Where cold-side mitigation is needed, integrators typically rely on window and battery/mechanical heaters and, less often, passive heat-sinking rather than active cooling — sized and verified against the specific mission's climatic category rather than assumed by default [23] [24] [25]. On the hot side, by contrast, the lens's +60°C ceiling already clears MIL-STD-810's most severe standard category, Hot Dry (A1), so heat rarely requires this kind of mitigation.

Storage temperature — what the lens must survive unpowered and optically idle before and after it flies, whether in a case, a shipping container, a forward staging area, or a vehicle cargo bay — tells a similarly favorable story. Storage ranges for imaging lenses typically run wider than their operating ranges [26], and Theia’s −30°C to +70°C storage range lines up well against MIL-STD-810’s most demanding standard heat category: Hot Dry (A1)’s 33°C to +71°C induced/storage range [22], as well as clearing Mild Cold (C0)’s −21°C to −10°C induced/storage range.

Which Iris Type Fits a Vibration-Optimized Application?

Gimbal payloads accumulate continuous vibration exposure over the operational life of the aircraft, and a lens is judged on mechanical simplicity as well as optical performance [34]. Three iris types are common in ultra-wide gimbal optics:

The fixed-iris configuration removes a moving part entirely from a payload where weight and reliability, not variable exposure control, are the binding constraints — the stronger recommendation for small UAS integrations where the mission doesn’t call for field-adjustable exposure.

Manual iris remains the more common configuration where some field-set exposure control is wanted without the continuous-actuation wear of a third type: DC auto-iris.

DC auto-iris lenses remain common elsewhere in the camera market because they continuously compensate for gradual, all-day ambient light changes — a function historically carried by the lens in analog CCTV/security-camera designs, rather than by camera electronics [35].

Day/night mode switching (removing the IR-cut filter to shift from color to monochrome/IR imaging) is a related but separate function; in most modern cameras it's triggered by the sensor's electronic gain crossing a threshold, not by the auto-iris drive signal itself [36].

For a gimbal payload, where exposure control and day/night switching are already handled digitally by the sensor and gimbal electronics, DC auto-iris doesn't solve a problem the platform hasn't already solved elsewhere — which is why manual or fixed iris remains the better fit for a weight- and vibration-optimized gimbal integration.