| 摘要 |
PROBLEM TO BE SOLVED: To obtain a photo-acoustic analyzer in which a plurality of measurements can be made repeatedly in a short time by irradiating a specimen with a plurality of monochromic lights subjected to amplitude modification by reference signals having different carrier frequency. SOLUTION: In order to detect the concentration of a light absorbing substance in a specimen, the specimen is irradiated with a plurality of monochromic lights having different wavelength. The monochromic lights are subjected to amplitude modification by reference signals having different carrier frequency. Furthermore, sound waves produced through photo-acoustic effect are demodulated by the difference carrier frequencies. More specifically, lasers 112, 113 oscillate lights of wavelength λ1, λ2 which are subjected to intensity modulation by optical modulators 120, 121 according to reference signals 204, 205. An organism 150 is irradiated simultaneously with these lights. The absorption of light takes place in the organism 150 and a pressure wave is generated through volume expansion caused thereby. The pressure wave is converted through a piezoelectric element 171 and an acoustic coupler 172 into an electric signal which is fed through an amplifier 18 to demodulation circuits 181, 182 and demodulated. |
