Patent Number: 6,310,729

Title: Dichroic mirror

Abstract: A dichroic mirror comprises a transparent substrate, a dielectric multilayer structure formed thereon. The dielectric multilayer structure includes a main multilayer structure comprised of high refractive index layers and low refractive index layers formed alternately, each layer having an optical thickness of .lambda./4 where .lambda. is the designed central wavelength, a first transmittance regulating film provided between the main multilayer structure and the transparent substrate, and a second transmittance regulating film provided on the other side of the main multilayer structure. The first and second transmittance regulating films typically have a three- or four-layer structure of intermediate refractive index layers and low refractive index layers formed alternately. The intermediate refractive index layers have a refractive index lower than but close to that of the high refractive index layers.

Inventors: Tsukamoto; Seitoku (late of Yokohama, JP)

Assignee: Canon Kabushiki Kaisha

International Classification: G02B 27/14 (20060101); G02B 5/30 (20060101); G02B 5/28 (20060101); G02B 027/14 (); G02B 001/10 (); G02B 005/08 ()

Expiration Date: 10/30/2018