APPARATUS AND METHOD FOR REDUCING SOLAR NOISE IN IMAGING LIDAR, UNDERWATER COMMUNICATIONS AND LIDAR BATHYMETRY SYSTEMS

• Main Author: KEELER; R. NORRIS
• Format: Patent
• Language: English
• Published: 09.03.1993
• Subjects: ANALOGOUS ARRANGEMENTS USING OTHER WAVES; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION ORRERADIATION OF RADIO WAVES; MEASURING; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS; RADIO DIRECTION-FINDING; RADIO NAVIGATION; TESTING

The present invention employs an optical filter which rejects substantially all wavelengths except for a selected wavelength. This invention eliminates most optical noise (e.g., solar noise) in LIDAR (light detection and ranging) imaging systems as well as LIDAR bathymetry systems and underwater submarine communication systems. The selected wavelength corresponds to the transmission wavelength of the laser. In accordance with the LIDAR systems of the present invention, a laser beam of the selected wavelength is projected at a body of water wherein a return beam is generated. The reflected or backscattered return beam is collected by optics which then directs the beam at the filter. The beam is filtered so that substantially all other wavelengths not corresponding to the selected wavelength are rejected, thereby eliminating most optical noise, particularly solar noise. The filtered beam is then detected. In accordance with the underwater communication system of the present invention, an encoded laser beam of the selected wavelength is projected at an underwear location (e.g., submarine). This beam is collected by optics which then directs the beam at the filter. Again, the beam is filtered so that substantially all other wavelengths not corresponding to the selected wavelength are rejected, thereby eliminating most optical noise, particularly solar noise. The filtered beam is then detected and provides a signal to be decoded.