Patent ID: 6507404
Filing Date: 2003-01-14
Classification: G01J

Abstract:
A method of measuring an optical wavelength using an interference optical system, said interference optical system splitting an input light beam in two, giving a predetermined optical path length difference to the resultant two light beams and thereafter synthesizing them to generate interference fringes, said method comprising the steps of:introducing a reference light with a known wavelength &lgr;1 from a coherent reference light source into a first interference optical system; introducing a test light with an unknown wavelength &lgr;2 from a coherent test light source into a second interference optical system; modulating interference fringes obtained from the respective interference optical systems by giving a same sinusoidal wave vibration having a predetermined amplitude of d and an angular frequency &ohgr; to the respective optical path length differences for said reference and test lights in said interference optical systems; and computing said wavelength &lgr;2 of said test light by detecting degrees of modulations of the respective interference fringes obtained for said reference and test lights and using a ratio between said degrees and said wavelength &lgr;1 of said reference light.