UAV Imaging Systems

motorized continuous zoom IR lenses
Figure: A selection of motorized continuous zoom IR lenses

Lightweight MWIR Zoom Lenses for UAVs

When equipped with high-performance thermal imaging systems, UAVs, also known as drones, lend themselves to a wide range of defense, government, and commercial applications. In the areas of defense and government, UAVs are used for military and police surveillance, border control, monitoring, and search-and-rescue operations. Commercial drones with thermal imaging capabilities are playing a prominent role in inspecting electrical power lines, oil pipelines, and other infrastructure. Thermal imaging drones are also being used to assist in firefighting operations by locating and assessing fires, even when visibility is poor.

As UAV technology is implemented for increasingly varied and sophisticated tasks, there has been a call to improve imaging performance. Accordingly, detector manufacturers are working on improving resolution while maintaining relatively small footprints to accommodate usage in smaller drones. While detector resolution should improve imaging performance, this must be accompanied by improvements in lens quality. To match the performance of state-of-the-art detectors, lenses with lower F/#'s and minimal aberrations are necessary to improve low-light performance. Furthermore, lenses must also possess long focal lengths for use when UAVs capture images from large distances.

There are also unique requirements for optical elements to be used in drones. The three most important factors to consider when developing optical components for UAV payloads are summarized by the acronym SWaP, which stands for size, weight, and power consumption. UAV payloads, especially for smaller commercial UAVs, impose strict size and weight restrictions. Furthermore, power consumption must be reduced to help lower fuel usage, thus maximizing flight time. The challenge thus falls on lens manufacturers to design and produce compact, lightweight lenses while not compromising image performance. Various solutions are required to meet these challenges, including the use of innovative optical and mechanical designs, exotic materials, free-form optics, and unique lens coatings.

Diamond turning technology can be used to produce aspheric and diffractive surfaces with exceptional levels of accuracy and quality. Aspheric lens surfaces provide improved optical performance over their spherical counterparts for IR imaging. Aspheric-diffractive lens surfaces allow for correction of both chromatic and spherical aberrations. Consequently, lenses produced by diamond turning can reduce the number of optical elements, leading to a reduction in overall size and weight. Continuous zoom lenses, which maintain focus under changing conditions, can also reduce lens size and weight compared to the use of multiple single-FOV lenses. A continuous zoom lens also enables better imaging adaptability during UAV operation. The use of durable, anti-reflective coatings also improves optical performance with minimal size/weight impact.

MKS Ophir is a worldwide leader in the design and manufacture of high-performance LWIR and MWIR lenses that meet the strict requirements of the UAV industry. Working in collaboration with defense and commercial customers, MKS Ophir designs IR lenses with unparalleled optical performance while also considering the SWaP constraints of the UAV payload. This is accomplished using advanced manufacturing technologies including diamond turning processes, free-form optics fabrication techniques, and advanced lens coating. The resulting continuous zoom and athermal lenses possess superior IR image quality, are lightweight with a small footprint, and can function in extreme environmental conditions. MKS Ophir's LightIR is a high-performance, IR thermal imaging lens designed specifically for use in UAV payloads. The LightIR is a motorized, continuous zoom lens and is the lightest and most compact lens of its type available on the market today.

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