To strive for the goal of further improving the overall performance of low-light-level Gen.Ⅲ image intensifier tube, modifications and innovations in the making of GaAs photocathode are already underway revolving around the basis of existing research, through which the sensitivity of GaAs photocathode is considerably improved from 1200μA/lm to above 1800μA/lm, 2000μA/lm (typical value), and it won’t drop within the 1000hrs’ storage inside the station according to the experiment on the photoemission stability of high-sensitivity GaAs photocathode. In short, highly distinguished characteristics of high sensitivity GaAs photocathode like wide response range, superior quantum efficiency and 1.06μm infrared response wavelength, promise its remarkable significance in both the enhancement of the overall performance and the prolongation of the operational life-span of low-lightlevel Gen.Ⅲ image intensifier tube.
In order to project the laser command information to the proper distance , so a laser zoom projective lens with variable total track optical system is designed in the carrier-based aircraft landing system. By choosing the zoom structure, designing of initial structure with PW solution, correcting and balancing the aberration, a large variable total track with 35~× zoom is carried out. The size of image is invariable that is φ25m, the distance of projective image is variable from 100m to 3500m. Optical reverse design, the spot is less than 8μm, the MTF is near the diffraction limitation, the value of MTF is bigger than 0.4 at 50lp/mm.
When the field of operation of precision strike missiles is more and more complicated, autonomous seekers will soon encounter serious difficulties, especially with regard to low signature targets and complex scenarios. So the dual-mode sensors combining an imaging sensor with a semi-active laser seeker are conceived to overcome these specific problems. Here the sensors composed a dual field of view mid-infrared thermal imaging camera and a laser range finder have the common optical aperture which produced the minization of seeker construction. The common aperture optical systems for mid-infrared and laser dual-mode guildance have been developed, which could meet the passive middle infrared high-resolution imaging and the active laser high-precision indication and ranging. The optical system had good image quality, and fulfilled the performance requirement of seeker system. The design and expected performance of such a dual-mode optical system will be discussed.
For the realization of target detection and monitoring of a wide range with the unmanned aerial vehicle (UAV), an UAV-based reconnaissance and surveillance system was proposed. The main optical system was consisted of visible camera with narrow field of view (FOV), mid-wave infrared camera (MWIR) and long-wave infrared camera (LWIR). The aperture was shared and the spectrum was disparted in the terminal. The diameter of primary mirror was 170mm. The focal length was 880mm and field of view was 0.86º for visible camera with narrow FOV, the focal length was 880mm and field of view was 0.8º for MWIR camera, the focal length was 220mm and field of view was 3.2º for LWIR camera. Considering the influence of temperature on the imaging quality, a kind of material with good thermal property was used as mirror substrate. The athermalization method was introduced to realize a high image quality in a wide temperature range of -40℃～+65℃. Zoom optical system was adopted in the visible camera with middle FOV and wide FOV, the view of it was 3.4º～34º. The operating distance of laser channel was designed to 20km. The results of the design indicated that this set of optical system could be used for ground target detection and monitoring of a wide range, met user’s requirement.