Method of measuring Raman spectra and laser Raman spectrophotometry system

Claim 2

A laser spectrophotometry system, comprising: a first laser source (1) for emitting a first laser beam of a first wavelength; a second laser source (2) for emitting a second laser beam of a second wavelength different from said first wavelength; first optical means (3, 9) for alternately and periodically transmitting said first and second laser beams at a predetermined frequency and directing the first and second laser beams along a substantially same path to a specimen to be measured; second optical means (13, 14) for detecting a light signal generated from the specimen and converting the light signal into an electrical signal; and phase-sensitive detecting means (18) for phase- sensitively detecting the electrical signal at said predetermined frequency to detect a different signal essentially formed by subtracting a signal component corresponding to said second laser beam from a signal component corresponding to said second laser beam.

Claim 3

A laser photometry system according to Claim 1, wherein: said first optical means (3, 9) includes reference signal means (32, 33) for generating a reference electrical signal having said predetermined frequency and a constant phase relation with said alternately transmitted first and second laser beams, the reference electrical signal being supplied to said phase-sensitive detecting means (18).

Claim 4

A laser spectrophotometry system according to Claim 1 or 2, further comprising: controller means (22) for controlling the intensity of said second laser beam emitted from said second laser source (2).

Claim 5

A laser spectrophotometry system according to Claim 1 or 2, wherein: said first optical means (3, 9) further includes bladed sector (31) having transmitting part and shutting part of equal width.

Claim 6

A laser spectrophotometry system according to Claim 2, wherein: said reference signal means (32, 33) includes a beam splitter means (32) for splitting part of the transmitted first laser beam and light detector means (33) for receiving and converting the splitted first laser beam into the reference electrical signal.

Claim 7

A laser spectrophotometry system according to Claim 3, wherein: said controller means (22) is capable of varying the intensity of said second laser beam in such a range that the output of said phase-sensitive detecting means is compensated for a noise component which is substantially insensitive to exciting wavelength.

Claim 8

A laser Raman spectrophotometry system for spectrometrically analyzing a specimen material to be examined, comprising: a first laser light source (1) for emitting a first laser light beam (4) of a first wavelength for producing Raman-scattered light from said specimen (11); a second laser light source (2) for emitting a second laser light beam (5) of a second wavelength for producing noise component light from said specimen (11); means (22) for regulating intensity of said second laser light beam (5); optical switch means (3, 31) for transmitting therethrough said first and second laser light beams (4, 5) alternately and periodically at a predetermined frequency; optical path joining means (9) for joining optical paths of said first and second laser light beams (4, 5) with each other so that both of said laser light beams (4, 5) follow a same path thereafter, said joining means being located downstream said optical switch means (3); first condenser means (10) for focusing said laser light beams transmitted through said optical path joining means (9) at a position of said specimen (11); second condenser means (12) for collecting lights including luminescence and Raman-scattered light produced at said specimen under excitation by the laser beams focused by said first condenser means (10); spectrometer means (13) for receiving said luminescence and said Raman-scattered light transmitted through said second condenser means (12) for dispersing into spectrum; opto-electrical detector means (14) for converting components of said luminescence and Raman-scattered light dispersed by said spectrometer means (13) into corresponding electrical signal; and phase-sensitive detecting means (18) for performing phase sensitive detection of said electrical signal produced by said opto-electrical detector means (14) at said predetermined frequency of said optical switch means.

Claim 9

A laser Raman spectrophotometry system for spectrometrically analyzing a specimen material to be examined, comprising: a first laser light source (1) for emitting a first laser light beam (4) of a first wavelength for producing Raman-scattered light from said specimen (11); a second laser light source (2) for emitting a second laser light beam (5) of a second wavelength for producing noise component light from said specimen (11); means (22) for regulating intensity of said second laser light beam (5); optical switch means (3, 31) for transmitting therethrough said first and second laser light beams (4, 5) alternately and periodically at a predetermined frequency; optical path joining means (9) for joining optical paths of said first and second laser light beams (4, 5) with each other so that both of said laser light beams (4, 5) follow a same path thereafter, said joining means being located downstream said optical switch means (3); first condenser means (10) for focusing said laser light beams transmitted through said optical path joining means (9) at a position of said specimen (11); second condenser means (12) for collecting lights including luminescence and Raman-scattered light produced at said specimen under excitation by the laser beams focused by said first condenser means (10); spectrometer means (13) for receiving said luminescence and said Raman-scattered light transmitted through said second condenser means (12) for dispersing into spectrum; opto-electrical detector means (14) for converting components of said luminescence and Raman-scattered light dispersed by said spectrometer means (13) into corresponding electrical signal; and phase-sensitive detecting means (18) for performing phase sensitive detection of said electrical signal produced by said opto-electrical detector means (14) at said predetermined frequency of said optical switch means.

Claim 10

A method of adjusting the laser Raman spectrophotometry system for spectrometrically analyzing a specimen material to be examined according to Claim 7, wherein the luminescence signal component is eliminated from the output signal produced from said phase-sensitive detector means (18) with only the Raman-scattered light signal component being phase-detected, comprising adjusting intensity of luminescence produced at said specimen (11) under excitation by said second laser light beam (5) to the level of intensity of luminescence spectrum produced under excitation by said first laser light beam (4) destined for exciting the Raman scattering through adjusting said adjusting means (22).