摘要:
A light wavelength measuring apparatus is designed to obtain a wavelength (.lambda.) of target light, by using the number (N) of interference fringes having predetermined repetitive waveforms generated when an optical path length is changed by a change amount (D.sub.S) by continuously moving a movable portion (7) of an interference spectroscopic unit (1) at a constant speed throughout a predetermined distance (D.sub.S), according to .lambda.=D.sub.S /N. A wave counter (13) forms waveform count information (Na) by counting the number of specific points, corresponding to each other in respective periods of the interference fringes, throughout an interval between predetermined measurement start and end points. A reference pulse generator (21) generates a reference pulse having a frequency higher than that of the repetitive waveforms of the interference fringes. A detector (22a, 23a) detects a first number of reference pulses present in one period of the interference fringes together with a second number of reference pulses present in an interval between the measurement start point and the first specific point, of the interference fringes, following the measurement start point, and a third number of reference pulses present in an interval between the last specific point of the interference fringes and the measurement end point. A CPU (26) corrects the waveform count information (Na) obtained by the wave counter using the first, second, and third numbers of reference pulses detected by the detector to obtain waveform count information (N.sub.A) including a fractional value, thereby calculating the wavelength of the target light according to .lambda.=D.sub.S /N.sub.A.