Patent ID: 7050164

Claim:
A spectrophotometer having a light source for emitting a sample optical beam and a reference optical beam, a photodetector that changes in sensitivity with changes in applied voltage, an analog-to-digital converter by which electrical signals from said photodetector are converted into digital signals, a digital storage means for storage of said digital signals corresponding to the light of said beam, and a control means for controlling a voltage applied to said photodetector, wherein said control means is further equipped with an applied voltage storage means for previously storing said applied voltage corresponding to a wavelength thereof, said applied voltage being corrected so as to be in a proper range, wherein when measuring a sample, so as to detect said sample optical beam and said reference optical beam, a voltage value corresponding to said wavelength to be measured is read out from said applied voltage storage means so as to apply a voltage having said voltage value to said photodetector.