A CW-CO2 laser range finder using heterodyne detection and on-off amplitude modulation
Abstract
A CO2 laser range finder that uses an acousto-optic modulator to obtain an amplitude modulated optical beam from a CW laser was built. An on-off deflected beam was obtained by driving the modulator with a carrier modulated by a periodic binary code. The received infrared radiation was heterodyne detected. After envelope detection of the heterodyne signal, the signal-to-noise ratio was improved by applying a digital integrator. Ranging was carried out by calculating the delay of the received code by cross correlation, using a minicomputer implemented in the system. Using 1 W average beam power and measuring time 1 sec, ranges of several kilometers were determined from stationary targets.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- August 1983
- Bibcode:
- 1983STIN...8421871L
- Keywords:
-
- Amplitude Modulation;
- Continuous Wave Lasers;
- Laser Range Finders;
- Optical Heterodyning;
- Acousto-Optics;
- Carrier To Noise Ratios;
- Digital Integrators;
- Signal Processing;
- Lasers and Masers