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1 May 1991 Realization of heterodyne acquisition and tracking with diode lasers at lambda=1.55 μm
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Proceedings Volume 1522, Optical Space Communication II; (1991)
Event: Munich '91 (Lasers '91), 1991, Munich, Germany
We designed, realized, and tested a laboratory model of an optical intersatellite link employing InGaAS DFB semiconductor lasers operating at a wavelength of 1.55km. Heterodyne sensing was used for both the spatial acquisition and the spatial tracking processes. During the acquisition process spiral scanning of the transmitter area of uncertainty is performed. A microcomputer controls the receiver operation. For each spatial search position the local oscillator laser is swept through a predefined frequency uncertainty range until the beat signal appears at the desired intermediate frequency (IF=700MHz). A heterodyne quadrant detector was realized by using a four-sided reflecting pyramid to split the superimposed beam. During tracking, the microcomputer reads the tracking sensor output signals, calculates the required antenna correction, and feeds the appropriate signals to the beam steering unit. Thus we realized a digital tracking loop, whereas the intermediate frequency is stabilized by means of an analog control loop. The tracking sensor angular resolution -withoutusing a telescope - is 5rad, limited by the digital signal processing, at a detector field of view of lmrad. The typical tracking error measured for various system conditions amounts to less than 1/20 of the FOV, i.e. less than
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Martin F. Hueber, Walter R. Leeb, and Arpad L. Scholtz "Realization of heterodyne acquisition and tracking with diode lasers at lambda=1.55 μm", Proc. SPIE 1522, Optical Space Communication II, (1 May 1991); doi: 10.1117/12.46090;

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