WAVELENGTH DETECTOR, WAVELENGTH STABILIZATION LASER DEVICE, AND IMAGE DISPLAY DEVICE

摘要

A wavelength detector capable of distinguishing between the changes of a transverse mode and of a longitudinal mode of a laser light and thus detecting the change of the wavelength of the laser light with high accuracy is provided. In a wavelength detector 13 : a diffraction grating 16 diffracts a laser light emerging from a laser light source 10 ; photodetectors 50a and 50b are positioned symmetrically with respect to a 0-order diffracted light diffracted by the diffraction grating 16 ; and light incidence surfaces 51 a and 51 b of the photodetectors 50 a and 50 b, respectively, have the same shape and are each divided into a plurality of areas. The wavelength detector 13 detects the change of the wavelength of the laser light based on a value obtained by dividing the difference value between the sum of light intensities measured by all of the plurality of divided areas of the photodetector 50a and the sum of light intensities measured by all of the plurality of divided areas of the photodetector 50b, by the sum of light intensities measured by all of the plurality of divided areas of the two photodetectors 50a and 50b.