The rotation mirrors synchronization block for separation of optical channels

Pap, VO, Hlushchenko, YM, Medvedskiy, MM
Kinemat. fiz. nebesnyh tel (Online) 2021, 37(3):84-90
https://doi.org/10.15407/kfnt2021.03.084
Start Page: Instruments and Devices
Language: Ukrainian
Abstract: 

As it is known, the satellite laser ranging method is to measure the transit time of a laser pulse from a transmitter to the satellite and back to the receiver. A special feature of the TPL telescope is that the transmitting and receiving of the laser signal are performed with the same telescope. This requires additional equipment to separate these signals. Besides, this telescope is also used for visual tracking of the object, which adds complexity to the optical design. In most cases, the signals are separated mechanically, i.e. using rotating mirrors. In one position, the mirrors transmit the signal to a specific channel, in the other one, they reflect the optical signal into another channel. Each mirror splits one optical channel into two channels. The rotational speed corresponds to the frequency of the laser transmitter. Both mirrors rotate at the same frequency but with a different phase. A logic circuit, which is built on two D-triggers and one 2-input NAND element, is used as a phase detector. The article discusses the scheme and principle of the operation of the mirror synchronization device by signals of the control computer and mirror position sensors. This device has been successfully used at the “Riga-1884” laser location station of the University of Latvia.

Keywords: laser location of the Earth artificial satellites, optical channel separation, phase detector, TPL-1 telescope
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