MWIR Thermal Lens

A: LightIR 16-180 mm f/3.6 continuous zoom lens is a compact, folded design that reduces size while maintaining a long effective focal length (EFL). It uses fewer optical elements than similar focal-length lenses to reduce weight. It is designed with low power consumption to meet design criteria.

A: Almost any application can benefit from reducing size, weight, and power, but in some applications it is essential. Drone and UAV designers are constantly balancing the size and lift capacity of aerial vehicles with the sophisticated technology needed in the payloads. The LightIR 16-180 mm f/3.6 lens allows for a sophisticated, long-range MWIR sensor while limiting the payload size, weight, and power consumption. This makes it ideal for airborne gambles on SWaP-constrained platforms. It is specifically designed to enhance imagery in MWIR 640x512 10 µm pitch sensors preferred by engineers with SWaP constraints.

A: Even though SWaP constraints limit size, weight and power, the performance required of the systems cannot be compromised. Imaging systems must maintain the ability to produce clear, crisp images for the end user. OUR LightIR 16-180 mm f/3.6 lens maintains excellent MTF (modulation transfer function) as well as maintaining focus throughout the zoom. It also includes fast zoom and focus, tight boresight, low power consumption, wide operational temperature range, and high durability in harsh environmental conditions. WE have created a unique design that implements strict quality control to achieve the best images any given sensor can produce.

A: Maintaining high performance in any lens begins in the design phase, the key to the designs is to build in performance and manufacturability. Near diffraction limit MTF with a design that allows for some minor tolerances in the build cycle leads to a superior product that meets or exceeds its testing requirements. OUR state-of-the-art manufacturing facilities maintain tight quality control over the entire manufacturing process from design to delivery, to ensure a superlative product.

A: Single- and dual-FOV (field of view) lenses are not well suited to SWaP constraints. Single FOV does not provide the flexibility required by systems engineers and dual-FOV cannot meet size and weight constraints. OUR LightIR 16-180 mm f/3.6 lens provides a wide FOV for detection and situational awareness and continuously narrowing FOV for identification of objects of interest. The folded optical design allows this in a smaller volume package perfect for SWaP design constraints. In order to withstand harsh environmental conditions, the lens is offered with high durability (HD) and low reflection hard carbon (LRHC) AR coatings.

A: Drone and UAV design engineers are perpetually balancing size and capability requirements for each aerial system. Larger aerial vehicles have larger lift capacities, but cannot be readily moved by the people who operate them. Smaller aerial vehicles have limited range and limited lift capability. In order to balance these constraints, design engineers detail the size, weight, and power requirements for each subsystem used in a particular design. WE works with sensor manufacturers as well as drone and UAV designers to provide the best optics to meet these rigorous needs. LightIR 16-180 mm f/3.6 is the culmination of this teamwork between optics designers and the end users of complex aerial systems.

A: When it comes to developing optical components and optical systems for UAV payloads, three factors must be measured. These factors can be summarized by the acronym SWaP – size, weight, and power consumption. UAV payloads, especially for smaller commercial UAVs, impose strict size and weight restrictions. Power consumption must be reduced to minimize fuel usage, thus maximizing flight time.

The optical payloads for small autonomous aerial systems must be able to provide high optical performance despite their compact form. Detectors are increasing in both resolution (number of pixels) and format (size) while decreasing in pixel size, which puts pressure on optical manufacturers to make smaller, lighter optics with lens quality that will still allow for maximum imaging performance.
Various technologies are being used to meet these optical needs. These technological solutions include innovative optical and mechanical designs, free-form optics, and unique lens coatings.

A: Over the last 10 years, multi-spectral optical systems have been used by system integrators in the defense and aerospace industries, in surveillance and monitoring, and certain commercial applications. Multi-spectral optics enable many new possibilities for defense and national security missions on land and sea. Multi-spectral imaging systems enable the combining of multiple cameras into one, to significantly improve performance without increasing size and weight. These systems generally have long focal lengths and are meant for long-distance surveillance, possibly tens of kilometers. The multi-spectral optics enable maximum error correction and allow for a wider field of view, performing to a high level across a wide range of wavelengths (Short-wave IR, Mid-wave IR, Long-wave IR, Visible and Near IR). They allow for high day/night performance in situations where vision is obscured, such as low lighting and adverse weather conditions.

For example, multi-spectral optics is integrated into the optical systems of large unmanned aerial vehicles (UAVs) for the long-distance aerial monitoring of agricultural field temperature using IR, as well as in the aerospace industry, for satellites and long-range telescopes.

A: A multispectral electro-optical system (EOS) combines multiple optical channels into one, allowing significantly improved performance while reducing size and weight – all thanks to the inclusion of large mirrors. An electro-optical day/night system built for aircraft payloads providing high performance in harsh weather conditions is a perfect example of a multispectral EOS.

A: Long-range defense, surveillance, and monitoring applications use multi-spectral optical systems. Certain commercial applications also use a multi-spectral EOS. For example, aircraft or large UAVs often carry a multi-spectral EOS with an integrated large mirror in the payload.

A: Unlike lenses that are often bandwidth-limited, large mirrors combine several imaging bands in the visible, NIR, SWIR, MWIR, and LWIR, allowing significantly improved performance without increasing the size and weight of the EOS. Large mirrors perform to a high level across a wide range of wavelengths including laser-based applications such as laser range finders (LRF) and laser designators.

A: With its name taken from Greek mythology, narcissus is one of the unwanted effects of thermal imaging, whereby a cold detector images the reflection of itself and displays it in the processed video output. Whenever the thermal detector senses variations in background radiation caused by reflections from lens surfaces, the phenomenon of narcissus may occur.

A: Typically, the narcissus effect comes from the detector cold shield. The cold shield is kept at cryogenic temperatures, while the lens' temperature is usually near ambient temperature. Narcissus occurs when the image of the cold shield is reflected from a surface in the lens train and is focused on the detector. In such cases, the image of the cold shield shows in the middle of the display as a dark or bright circle. Because of the difference in temperature between the cold shield and the lens assembly, every infrared zoom lens in a system with a cooled detector is prone to narcissus.

A: To test levels of narcissus when manufacturing a lens system, WE set up a narcissus simulation. Every surface of the lens system is examined through the entire zoom sequence, at many intervals. If the narcissus effect occurs at any point, it is measured and analyzed, and methods are put into place to correct it.

A: Narcissus reduction should be addressed during the manufacturing of a lens system. Here at WE, this is done through unique lens designs and anti-narcissus coatings that will prevent the production of back reflections that could focus on the detector and cause the narcissus effect.

A: OUR addresses boresight retention using tight tolerances for all optical and mechanical elements, as well as backlash-free design. Using OUR zoom lenses, once the zoom position is changed, the boresight is maintained, meaning that no adjustments are needed during optical system operation. This is an integral feature in zoom lens design, which we consider as part of the standard requirements and quality tests.

A: OUR boresight error ranges from 0.15 mm to 0.35 mm at the focal plane.

A: The focal length determines the field of view (FOV) of the thermal imaging camera. The longer the focal length, the smaller the FOV, which translates into more pixels across a target at a fixed range (meaning, the target angle divided by the IFOV angle).

A: Extenders allow flexibility. A lens can be replaced easily, using the same basic lens body, with no need for hardware or software modifications. This lowers the complexity of the design and can also result in reduced NRE costs. Yet, reduced cost is not always achieved. Size and weight are mostly a disadvantage, as a second optical assembly is added to an existing one.

A: Most of OUR lenses cover a wide range of temperatures, from -30°/40°C to 70°c, and even 85°c. Using proper coating and sealing techniques, the lenses are also resistant to high humidity. Dust and vibration are also environmental factors that are tested, to ensure resistance to harsh environmental conditions. Thanks to these features, OUR lenses answer a wide range of application demands. In commercial applications, such as UAVs and drones, vibration management is crucial, as is the temperature range.OUR key competitive advantage in IR zoom lenses is the ability to maintain a high level of optical performance, which is, for example, characterized by the modulation transfer function (MTF) throughout the temperature range, and in different environmental conditions. OUR lenses provide outstanding performance, and an MTF close to the diffraction limit, over the entire temperature range, which is a critical demand for many applications.