Patent ID: 7308174

Claim:
An optical device comprising: light transmitting means; a slit defined in said light transmitting means; a filter member inserted in said slit for dividing a portion of signal light propagated through said light transmitting means; and a resin filling a gap between said slit and said filter member within said slit; said filter member having a substrate and an optical thin film disposed on a principal surface of said substrate; wherein a surface of said filter member on said optical thin film is defined as a first surface, a surface of said filter member on said substrate as a second surface, an inner wall surface of said slit which faces said first surface of said filter member as a first inner wall surface, and an inner wall surface of said slit which faces said second surface of said filter member as a second inner wall surface, wherein one or more of said first inner wall surface and said second inner wall surface of said slit, and said second surface of said filter member do not lie parallel to said first surface of said filter member, and said first inner wall surface comprises two planar surfaces that form an angle with respect to one another.