For space target photoelectric detection, the false-alarm problem is analyzed using the radiation theory. Firstly, the mathematic equations are deduced about the radiation of space target and its background; Secondly, the numerical calculation is carried out by taking U.S. KH-12 as research object, and the false-alarm problem is analyzed. The results show that: the main false-alarm sources are sun, earth-atmosphere system, moon and Venus. This work can provide theoretical reference for the design of space-based all-weather imaging system.
The cat-eye effect echo of optical system can be detected based on CCD, but the detection range is limited within several kilometers. In order to achieve long-range even ultra-long-range detection, it ought to select APD as detector because of the high sensitivity of APD. The detection system of cat-eye effect echo based on unit APD is designed in paper. The implementation scheme and key technology of the detection system is presented. The detection performances of the detection system including detection range, detection probability and false alarm probability are modeled. Based on the model, the performances of the detection system are analyzed using typical parameters. The results of numerical calculation show that the echo signal-to-noise ratio is greater than six, the detection probability is greater than 99.9% and the false alarm probability is less tan 0.1% within 20 km detection range. In order to verify the detection effect, we built the experimental platform of detection system according to the design scheme and carry out the field experiments. The experimental results agree well with the results of numerical calculation, which prove that the detection system based on the unit APD is feasible to realize remote detection for cat-eye effect echo.
Seeker is the key component in the laser guided weapons. Although the seeker has many anti-jamming measures such as the narrowband filter in the front of the seeker and the tracking gate processing circuit in signal processing part, and these anti-jamming measures are always effective for the low power jamming laser. As far as the high power laser which can pass though the filter is concerned, it is easy to make the detector saturate, which will lead the seeker into losing the capturing and tracking capability for the target. In the past ten years, the applied research of organic nonlinear materials which is according to the optical limiting effect has had great development in the laser technology field. And some of these materials have been put into practicability phase. This kind of materials is characterized by its wide absorption spectrum, obvious nonlinear effect and quick response speed, all of which excel the mineral. If this kind of materials can be applied into the laser seeker, it will remedy the laser seeker's defect that its protective capability is weak for the high power jamming laser. The whole applied scheme is present in this paper. And the anti-jamming capability of seeker is analysed constructively before and after the organic matter is applied in the laser seeker. The result indicates that this kind of method is viable in theory.
In a Faraday optical-fiber current sensor, it has many kinds of linear double refraction inevitably because of the circular degree error of the optical fiber, deformation of pressure, temperature effect and other reasons. It results in an additional phase difference, which will affect the detecting sensitivity and even decrease it to zero. A new method that can eliminate the effect of linear double refraction is offered in this paper with phase conjugate device after analyzing the foundational operation principle of the Faraday optical-fiber current sensor and the effect of the linear double refraction.