PROBLEM TO BE SOLVED: To provide a device for measuring a circular dichroism spectrum of the third-generation capable of performing dynamics measurement for chemical reaction where a dynamic change is fast, a process of an aggregate and conformational change of biopolymer, and the like. SOLUTION: The measuring method according to the present invention includes: constituting an optical chopper system by a polarizer having an azimuth angle of 45 degrees, a first polarization modulator with an optical axis of 0 degree, a wave plate with an optical axis of 0 degree and a polarizer having an azimuth angle of -45 degree; linearly polarizing light from a light source before entering a sample by using the optical chopper system; providing a second polarization modulator to polarize the linearly polarized light into modulation light having only circular polarization of light; and allowing a polarity of a voltage signal waveform of a driving voltage applied to the first polarization modulator to be inverted, so that light from the light source is subjected to chopper synchronized with each of right and left circular polarization of light to polarize the light from the light source into linear polarization having light intensity of a wave form in a rectangular wave shape. COPYRIGHT: (C)2013,JPO&INPIT
