BEAM SPLITTER, SINGLE-LENS REFLEX DIGITAL CAMERA USING THE SAME, AND AUTOFOCUS VIDEO CAMERA

摘要

PROBLEM TO BE SOLVED: To provide a non-polarization beam splitter having non-polarization properties in a wide wavelength region at low cost. SOLUTION: In the beam splitter splitting a luminous flux having 30 to 60°incident angle with low incident angle dependence and constituted of two prisms composed of a transparent base material having a refractive index of 1.43 to 1.56 and a multilayer film inserted between the prisms and having at least 9 layers formed by alternately layering high refractive index transparent films having a refractive index of 1.95 to 2.55 and low refractive index transparent films having a refractive index of 1.35 to 1.50, the surfaces in contact with the prisms of the multilayer film are the high refractive index films and the difference between the maximum reflectance and the minimum reflectance in 400 to 700 nm wavelength is 15% or less. COPYRIGHT: (C)2009,JPO&INPIT