A reflective-type infrared ray cut filter and associated manufacturing
method wherein the time and cost of manufacture are reduced and
manufacturing efficiency is improved are provided. In the infrared ray
cut filter 10 comprising a multilayer membrane 200 composed of no less
than 16 but no more than 32 layers of a high-refractive index thin
membrane 210 and a low-refractive index thin membrane 220 laminated in an
alternating fashion and formed on a glass substrate 100, the first layer
from the side of the glass substrate 100 is a high-refractive index thin
membrane 210 and the last layer is a low-refractive index thin membrane
220, and where the design wavelength is deemed .lamda., the first and
second layers are formed to have an optical thickness of no less than
.lamda./4, the third layer through a prescribed layer are formed to have
an optical thickness of no more than .lamda./4, the layers between the
prescribed layer and the last layer are formed to have an optical
thickness of no less than .lamda./4, and the last layer is formed to have
an optical thickness of no more than .lamda./4.