Sky High Tech: UltraCam advanced lens technology
29 April 2024
UltraCam lens design
GOING THE EXTRA MILE
With customers spread all over the world, the environmental conditions in which Vexcel cameras operate couldn't be more different—from oceans and mountains to glaciers and forests, humid and dry climates, stable and rapidly changing weather conditions. Wherever in the world, our customers share one goal—to max out the available flight time and collect as much high-quality data as possible. At the heart of achieving this ambitious goal is the choice and design of lenses for an aerial camera.
In this blog post, we'll explore the qualities that define a good lens and explain why we opt for custom lens design.
In our UltraCam Merlin and UltraCam Eagle camera lines, we have effectively implemented a true nadir camera concept without the need to tilt the nadir cones. To also achieve the large footprints of these systems, a large image circle is crucial as it allows us to accommodate multiple sensors behind a single lens. Additionally, in our UltraCam Osprey and UltraCam Dragon lines, the large image circle enables us to perform sensor shifts in the left and right oblique cones, maximizing image content utilization. Watch the video from Stefan Piller about the sensor shift here.
The need for a large image circle, combined with the high optical quality level that our UltraCams require to meet demanding standards, necessitates a custom lens design for our applications. This specialized approach guarantees that our camera systems provide the exact performance necessary for advanced aerial imaging tasks.
High precision. Custom lens technology contributes significantly to the high quality of UltraCam data.
Lens design: Reaching the diffraction limit is key
Recognizing the critical importance of lens design in aerial imaging, Vexcel has constantly prioritized optical excellence to achieve superior image quality. Our long-term collaboration with QiOptiq, a premier lens manufactured based in Germany, has been instrumental in developing exclusive, world-class lenses specifically tailored for our UltraCam aerial cameras. In general, there is a principal limit to the resolution of any optical system, due to the so-called physics of diffraction.
So one of the main goals in the design of any optical system should be reaching its diffraction-limitation, which means that resolution is limited only by the laws of physics and not by structure, type of glass, etc. While common lenses on the market today are far from this limit, we see diffraction-limited optical systems as absolutely necessary. Our lenses fully resolve the high-resolution CMOS sensors and are critical to achieve the strict quality requirements we set for aerial images.
Adapting to temperature variations
Temperature plays a pivotal role in lens performance. All aerial cameras on the market – including our UltraCam systems – use fixed-focus lens systems. When flying at low or high altitudes or in different climate zones, temperature changes inevitably result in slight changes of the focal length – a fact we do not want to accept.
To compensate, we equip each of our lenses with temperature sensors based on many years of research into the temperature behavior of lenses. This knowledge allows us to measure and precisely model any slight change of focal length for each lens to ensure a consistent focal length under any temperature conditions.
For more information about our patented Altitude Compensation method, watch the video with Marc Muick here.
Harnessing high dynamic range for optimal data collection
When flight days are limited by unfavorable weather conditions, but strict delivery deadlines must be met, flying during less-than-ideal lighting becomes a necessity. Here, the high dynamic range of our lenses comes into play. UltraCam lenses are designed for speed, gathering ample light and producing sharp images from the widest aperture without vignetting.
Coupled with sensitive, state-of-the-art image sensors, our UltraCam systems can operate in challenging conditions – be it low sun angles or overcast skies – without compromising image quality.
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High dynamic range allows for better visibility into shadows because it can capture a wider range of light intensities
Ensuring flexibility & versatility
A crucial aspect of our lenses includes their mechanical shutters, designed for easy field replacement without recalibration. This feature ensures immediate operational readiness, even after shutter lifecycle completion or replacements.
Furthermore, our UltraCam Eagle 4.1 camera series offers multiple lens kits with varying focal lengths, allowing customers to tackle different project requirements with a single camera. Like shutter replacement, lens exchanges can be easily done on-site by the trained user without recalibration, highlighting the Eagle's versatility as a mapping camera ready for a broad spectrum of project demands.
The exceptional design and composition of the UltraCam’s optical system delivers the performance our customers need to meet tight deadlines and adverse conditions, ensuring the delivery of the highest quality aerial data in the market today.
Explore the UltraCam product lines
