Title:
DIFFRACTED LIGHT DETECTOR
Document Type and Number:
Japanese Patent JP2989380
Kind Code:
B2
Abstract:
PURPOSE: To enhance sensitivity by making an opening at a position of an optical sensor, disposed on the diffracting plane of laser beam irradiating a specimen, irradiated with 0 order diffracting light and introducing the diffracting light through the opening into a cylindrical member thereby suppressing effect of the diffracting light on the sensor.
CONSTITUTION: Laser beam 2 emitted from a semiconductor laser 1 passes through a lens system 3 to produce a parallel beam 3 for irradiating a thread 10 being carried at high speed in the direction normal to the paper face. The thread 10 is carried while vibrating and fluff part 11 passes some times. The light beam 2a is then condensed through a lens system 4 so that a Fraunhofer diffraction pattern is formed at the position of an optical sensor 20. The sensor 20 comprises pin photodiodes with an opening 20a being provided in the vicinity of the optical axis and the sensor 20 is secured to a board 21 having a coaxial opening 21a. Light passes through the openings 20a, 21a and enters into a metal pipe 5. The pipe 5 has interior painted black so that incident 0 order diffraction light is caught as much as possible. This arrangement prevents 0 order light from entering into the sensor as stray light thus realizing high sensitivity detection.
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Inventors:
KATSURA SHINICHI
KAWAHARA HIROSHI
OOTA TAKASHI
KAWAHARA HIROSHI
OOTA TAKASHI
Application Number:
JP17984792A
Publication Date:
December 13, 1999
Filing Date:
July 07, 1992
Export Citation:
Assignee:
ONO SOTSUKI KK
International Classes:
G01N21/47; G01N21/89; G01N21/892; (IPC1-7): G01N21/89; G01N21/47
Domestic Patent References:
| JP495863A |
Attorney, Agent or Firm:
Masaki Yamada (1 person outside)
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