Views:3 Author:Site Editor Publish Time: 2020-06-03 Origin:Site
The Future Trends of infrared lens
Various methods are currently used to achieve athermalization. Using a combination of materials such as zinc sulfide, zinc selenide, and germanium can provide some passive optical athermalization. Hybrid passive / active mechanical athermalization technology is also used. The most commonly used structures include additional lens movements, which are also moved for other reasons such as zooming and focusing. These movements are calculated in real time or derived from a look-up table. The entire process includes careful selection of temperature sensors as part of the closed-loop system. Using glass replacement in the optimization process proved to be a feasible method to achieve passive athermalization of the infrared zoom lens system.
2. Diffractive optical element
Diffractive optical elements are increasingly used in visible and infrared optical systems. By reducing the number of lens elements, they can improve system performance while reducing cost and weight.
3. Quadric and aspherical
The use of quadric surfaces and aspheric surfaces is becoming more and more common, mainly because diamond turning technology is relatively easy to obtain these surface shapes.
The optical materials available in the infrared spectrum are still somewhat limited. Some materials, such as gallium arsenide, find greater use in special applications such as laser systems. Zinc selenide was selected as the material in the CO2 laser system because of its low absorption at 10.6 μm. Refractive index distribution-type lenses, commonly referred to as GRIN lenses, can reduce the number of lenses required in an optical system, thus reducing the overall size and weight of the system, and such lenses have been developed for use in visible light. However, before infrared gradient index lenses become a reality, there are still communication issues. Moreover, diamond turning aspheric surfaces can have the same effect in reducing aberrations. In addition, plastic materials can have a suitable refractive index in the infrared and are processed by injection molding for the infrared spectral band.
5. Detector technology
In recent years, with the development of line detector arrays, large area rectangular arrays and gaze arrays, infrared systems have also been developed. The advent of the gaze array eliminates the corresponding needs for scanning and pupil control. Therefore, contrary to afocal telescopes, there are more and more objective type systems. Infrared focal plane array has been developed and applied, it provides almost ideal photon-noise-limited. Uncooled arrays are also widely used in special applications.
The trend in infrared missile simulators is toward increasingly more realistic simulation of operational scenarios. The development trend of missile simulator is a more realistic simulation of operational scenarios. At the same time, the total number of optical components must be kept to a minimum in order to keep the radiation loss at a reasonable level. These conflicting requirements pose more difficult challenges for system designers.
7. Mirror Systems
The further use of mirror systems in infrared zoom applications is a practical trend now and in the future. Mirror systems may be particularly useful in multi-spectral applications in the visible and infrared regions. Unobstructed systems and off-axis systems offer certain advantages in terms of light energy collection and performance, compared to reflective systems with occlusion systems and refractive zoom lenses.
8. Wavelength Region
The shift from 8- to 12-μm to the 3- to 5-μm region has accelerated due to detector and system issues as well as the low cost of silicon as compared with germanium, zinc selenide, and zinc sulfide.
9. Optomechanical Considerations
For mechanically compensated zoom lenses, in some closed-loop applications, the cam is replaced by a stepper motor. Moreover, infrared zoom lenses and reflective systems will continue to become more compact.
10. Computer Optimization
The purpose of computer optimization is to reduce the optimization function to the minimum. The optimization function defines the performance of the optical system within some given boundary conditions. The obtained solution is a local minimum solution, which strongly depends on the starting point. Global optimization is a method where many local optimal solutions can be found, and the dependence on the starting point is relatively small. Some studies have shown that it is feasible to use global optimization to search for solutions to zoom lens design problems.