| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical apparatus which is equipped with a diffracting grating element for separating or combining a light flux and which can easily suppress light loss by suppressing spreading of the light flux. SOLUTION: The optical apparatus has the diffracting grating element which makes a 1st light flux of a 1st wavelength and a 2nd light flux of a longer wavelength than the 1st wavelength incident from different directions and which emits the 1st light flux in a direction of an incident source of the 2nd light flux. The optical apparatus satisfies relations: n2<n1×sinθ,Λ/λL≤1/(n1+n1×sinθ) and 1/(n1+n1×sinθ)≤Λ/λS≤1/(n2+n1×sinθ), wherein n1 denotes a refractive index of a 1st medium disposed at an incident side of the 1st light flux among media holding a diffracting grating therebetween, n2 denotes a refractive index of a 2nd medium disposed at its opposite side,Λdenotes a cycle of irregularity of the diffracting grating,λS denotes the wavelength of the 1st light flux,λL denotes the wavelength of the 2nd light flux andθdenotes an incident angle of the 1st light flux to the diffracting grating. COPYRIGHT: (C)2008,JPO&INPIT |
