Laser pulse code is an anti-jamming measures used in semi-active laser guided weapons.
On account of the laser-guided signals adopting pulse coding mode and the weak signal processing,
it need complex calculations in the frequency measurement process according to the laser pulse
code signal time correlation to meet the request in optoelectronic countermeasures in semi-active
laser guided weapons. To ensure accurately completing frequency measurement in a short time, it
needed to carry out self-related process with the pulse arrival time series composed of pulse arrival
time, calculate the signal repetition period, and then identify the letter type to achieve signal
decoding from determining the time value, number and rank number in a signal cycle by Using
CPLD and DSP for signal processing chip, designing a laser-guided signal frequency measurement
in the pulse frequency measurement device, improving the signal processing capability through the
appropriate software algorithms. In this article, we introduced the principle of frequency
measurement of the device, described the hardware components of the device, the system works and
software, analyzed the impact of some system factors on the accuracy of the measurement. The
experimental results indicated that this system improve the accuracy of the measurement under the
premise of volume, real-time, anti-interference, low power of the laser pulse frequency measuring
device. The practicality of the design, reliability has been demonstrated from the experimental point
The purpose of characterizing the image of large-sized photographic instrument is to make the directionality of three coordinate axises in the three-dimensional coordinate of the image and the directionality of three axises of coordinate in the frame of axes of the instrument keep the same direction. This problem was solved by a high-precision measurement system composed of double-theodolite and a set of communication system. Two cube prisms will be respectively placed on the image surface and the instrument. Every cube prism will stand for a three-dimensional coordinate from the image surface or the instrument. As a result, the interdependence of both coordinates from the image surface and the instrument can be obtained by measuring the interdependence of the both cube prisms with autocollimation survey axiom. In the survey system, two high-precision stations TDA5005 from Leica Company will be selected as double-theodolite and the interdependence of both coordinates can be achieved by moving the station only at one time. Therefore, this measurement system is a high efficient and high-precision surveying method to the image calibration of the large-sized photographic instrument. Based on the experiment, its measuring accuracy can reach arc-second level.
A kind of new optical interconnection element -- holographic Bragg grating with a red sensitive photopolymer is reported in this paper. Grating-splitting boards with equal intensity are designed and fabricated on a red sensitive photopolymer by Lloyd's interferometer of the special design, and they are successfully demonstrated in application of optical butterfly interconnection network.
We report the fabrication of waveguides gratings coupler in photoresist by using a volume holographic gratings and that of the holographic gratings by Red Sensitive Photopolymer at 632.8 nm. The holographic gratings can produce diffracted light of 0 and -1 orders with equal intensity. The two diffracted light beams yield the interference fringe of period in near field, which is as laser sources to expose the photoresist on waveguide.
A scheme of holographic Bragg grating for achieving optical butterfly interconnection is presented in this paper. Its essential structure units are Bragg grating-slitting board of volume phase holography (splitting ratio 1:1). Photopolymer with red light is used as holographic recording medium of making gratings. The effect of the scheme has been demonstrated.
We fabricated a digitized dual-frequency coupling gratings. And it was demonstrated experimentally that a two level digitization of the analog profile performs the waveguide interference between two free space waves.
A chirped grating was fabricated on CdSxSe1-x doped glass waveguide characterized by intensity dependent refractive indices to use for all-optic tunable interconnection. The focal line move of 80000 nm was observed when the power density of the guided wave was changed. Five possible locations of the focal line for optical interconnection are determined.