Patent ID: 7242697
Filing Date: 2007-07-10
Classification: G02B,G02F,H01S

Abstract:
1. A wavelength selection device including a wavelength selection filter for passing at least one component of at least one desired wavelength of an incoming light and reflecting components of wavelengths other than the at least one desired wavelength of the incoming light, wherein the at least one component having passed through the wavelength selection filter is reflected by a reflection mirror back to the wavelength selection filter, to thereby obtain the at least one component of the at least one desired wavelength, the wavelength selection device comprising: a linear polarizer arranged on a side of the wavelength selection filter from which the incoming light enters the wavelength selection filter; and only one element for rotating a polarization of light by 45 degrees, arranged at each of respective locations between said linear polarizer and the wavelength selection filter, and between the wavelength selection filter and the reflection mirror, wherein the incoming light is a light collimated by a collimating lens, and the reflection mirror is a flat mirror.