PROJECTION TYPE DISPLAY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an optical thin film which can decrease the charge in light-transmitting property in the wevelength direction when the angle incident on the multiayered optical thin film is changed. SOLUTION: The high-quality projection type display device with little irregularity in colors on a screen is obtained by using a dichroic mirror or dichotic prism which is produced by alternately laminating high refractive index material layers and low refractive index material layers with k:1 (where k is an integer >=2) optical film thickness ratio of the high refractive index material layers to low refractive index material layers.