We propose an optoelectronic measurement system for testing the optical parameters of infrared seeker, such as the position of the image plane, the size of the diffused spot, and the diameter of the scanning circle. The measurement method and operating principle of the optoelectronic measurement system have been introduced. The source of the stray light in the optoelectronic measurement system have been analyzed by using FRED software, and the stray light have been restricted effectively by a co-centered mica plate which closes to the substrate of pinhole. Experimental results show that the test error for the size of the diffused spot is less than ±0.01 mm, the test errors for the position of the image plane and the diameter of the scanning circle are less than ±0.02 mm.
An optical attenuator with special performances, such as wide spectrum, high precision, polarization-independent, and lager dynamic range, is the key device for testing the communicat ion link performance in free-space laser communicat ion systems. We propose a polarizat ion-independent variable optical attenuator based on rhombic prism. Two rhombic prisms are used to balance the polarization aberrat ions, and the incident surfaces of the rhombic prisms are perpendicular to each other. We control the incident angle of the rays, which incident the reflected surfaces of the rhombic prisms, between the Brewster angle and the critical angle, then the attenuation coefficient of the attenuator can be changed. The results of theoretical analysis and numerical simulation show that the designed attenuator is polarization independent, the wavelength range is from 790nm to 1550nm, the dynamic range of attenuation coefficient is from -40 dB to -3 dB, and the wavefront aberration is less than /20@974nm.
In This paper, we present an experimental design of measuring thermal expansion coefficient of the
carbon fiber optical tube based on the heterodyne laser interferometry. In the course of the experiment,
the error caused by the temperature changes of the external environment was considered, and the
compensation is carried out. The data of the experiment was recorded and analyzed. The curve of the
thermal expansion coefficient of the carbon fiber optical tube was close. The measurement of the
thermal expansion coefficient was finished within a small range of temperature changes. The thermal
expansion coefficient of the carbon fiber optical tube was 6 0.78 x 10<sup>-5</sup><i>m</i>/ ° C − × , which was consistent
with the experience value. Athermalization for the supporting structure of the Cassette optical system
was designed according to the results of the experiment.
In view of the light energy loss in central obscuration of coaxial reflex optical system, the design method of a kind of hollow beam generator is introduced. First of all, according to the geometrical parameter and obscuration ratio of front-end coaxial reflex optical system, calculate the required physical dimension of hollow beam, and get the beam expanding rate of the hollow beam generator according to the parameters of the light source. Choose the better enlargement ratio of initial expanding system using the relational expression of beam expanding rate and beam expanding rate of initial system; the traditional design method of the reflex optical system is used to design the initial optical system, and then the position of rotation axis of the hollow beam generator can be obtained through the rotation axis translation formula. Intercept the initial system bus bar using the rotation axis after the translation, and rotate the bus bar around the rotation axis for 360°, so that two working faces of the hollow beam generator can be got. The hollow beam generator designed by this method can get the hollow beam that matches the front-end coaxial reflex optical system, improving the energy utilization ratio of beam and effectively reducing the back scattering of transmission system.
The space coherent laser communication is a very potential and attractive mean as it allows higher
speed communication between satellites. The space coherent laser communication makes use of local
oscillator laser power to improve the power of received optical signal by mixing local oscillator laser and
optical signal together. However, the power of the local laser oscillator can not be increased infinitely, too
large but reduces the detection sensitivity. In this paper, starting from the principle of the signal-to-noise ratio
of the space coherent laser communication, we found the optimum local oscillator laser power was 28.174mw,
under the condition of the selected photodetector specific parameters. It is a great significant for high
detection sensitivity and low data error of the actual coherent detection system.
The space coherent laser communication is a very potential mean for high-speed laser
communication in the future, because the excellent receiver sensitivities can be achieved by coherent
detection techniques. The best coherent receiver sensitivity amounts to -59.4dBm at a data rate of 10Gbit/s
and a bit error rate of 10<sup>-9</sup>, which is obtained with phase-shift keying modulation in combination with
homodyne detection. In this paper, we investigated optical homodyne detection based on Costas phase-locked
loop in the space coherent laser communication system. We obtain optimum loop bandwidth of Costas
phase-locked loop and the maximum permissible laser line width based on Costas phase locked loop.