Title:
LASER DOPPLER CURRENT METER
Document Type and Number:
Japanese Patent JP3279116
Kind Code:
B2
Abstract:
PURPOSE: To measure an object, whose flow velocity is measured in a wide range in high accuracy.
CONSTITUTION: Semiconductor laser 20 undergoes frequency modulation with a sawtooth-shape injection current. The oscillated light is transmitted into an optical fiber through a collimeter 24 and an optical isolator 26. The light is split by an optical splitter 32. The laser light is transmitted into a probe 42 through optical fibers 28 and 30 having the difference in optical path lengths and condensed on a condenser part 44. The light, which is scattered with the condenser part 44, is transmitted into a photodetector 48 through the probe 42 and an optical fiber 46. Only the Doppler frequency is detected by heterodyne detection. The offset frequency can be arbitrarily set when the frequency modulation and the difference in optical. path length are determined at the appropriate values. Thus, the object, whose flow velocity is measured in the wide range, can be measured in high accuracy.
Inventors:
Satoru Kato
Hiroshi Ito
Tadashi Ichikawa
Manabu Kagami
Hiroshi Ito
Tadashi Ichikawa
Manabu Kagami
Application Number:
JP4093395A
Publication Date:
April 30, 2002
Filing Date:
February 28, 1995
Export Citation:
Assignee:
Toyota Central R & D Labs.
International Classes:
G01F1/66; G01P3/36; G01P5/26; G01P5/00; G01S17/58; G01S17/95; (IPC1-7): G01P5/00; G01F1/66; G01S17/58
Domestic Patent References:
| JP2201165A | ||||
| JP2107988A | ||||
| JP3131764A | ||||
| JP63200085A | ||||
| JP5759173A |
Attorney, Agent or Firm:
Atsushi Nakajima (1 person outside)