Optical feedback photodetection apparatus
US5614708A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 25, 1996 |
| Grant date | Mar 25, 1997 |
| Priority date | — |
| Expiry date | Jan 25, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S2301/02
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An optical feedback photodetection apparatus of the present invention achieves high-speed response while minimizing noise to obtain a high S/N ratio and a wide dynamic range. In the apparatus, on the basis of a modulated drive signal from a drive signal output circuit, a semiconductor laser outputs a light beam modulated at a frequency f.sub.0 to irradiate an object to be measured through an optical system, and the light beam reflected by the object is fed back to the semiconductor laser through the optical system. The intensity of the light beam from the semiconductor laser having an optical amplification function varies due to the return light beam. A photoconductive light-receiving device to which a modulated voltage signal at the frequency f.sub.0 from a voltage application unit is applied receives the light beam from the semiconductor laser and having an intensity varying due to the return light beam, thereby performing synchronous detection. A modulated current signal flowing through the photoconductive light-receiving device is converted to a voltage signal by a current/voltage conversion unit, and the low-frequency component of the voltage signal is extracted.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.