Wavelength stabilizing light source apparatus by maintaining a constant phase difference

摘要

A wavelength stabilizing light source apparatus comprising a light source, a beam splitter, a scanning mirror, a reflector, a first and a second light receiver, a phase detector and a wavelength stabilizer. The first light receiver receives a first interference signal formed from the interference between coherent light coming from the scanning mirror and coherent light reflected by the first reflecting surface. The second light receiver receives a second interference signal formed from the interference between the coherent light coming from the scanning mirror and the coherent light reflected by the second reflecting surface. The phase detector detects the difference in phase between the first and the second interference signal. The wavelength stabilizer stabilizes the wavelength of the light source by keeping constant the phase difference detected by the phase detector. The apparatus also includes an optical path length difference forming device for keeping a constant difference in length between the first optical path of its first member and the second optical path of its second member despite changes in temperature.