Patent ID: 7212285

Claim:
An optical measurement device for measuring an optical spectrum, comprising: a diffraction grating for dispersing measurement light to be measured, to produce diffracted light of selected wavelengths; a focusing lens for converging the diffracted light to produce a converged beam; a slit for passing part of the converged beam as incident light therethrough; a slit control section for varying a slit width of said slit at a scan speed to open or close said slit, thereby varying a passing bandwidth for the incident light, the scan speed being indicative of an optical frequency change per unit time; and a light receiving/measuring section for measuring power of received light passed through said slit, obtaining a level function which is indicative of a gradient corresponding to a profile of an envelope of the optical spectrum corresponding to change in optical frequency, and differentiating the level function with respect to the scan speed to reproduce a spectrum profile of the measurement light.