Imaging device
A close contact type imaging device is an imaging device for acquiring an image of an object in a state that the object is in close contact to an image sensor. This imaging device has an angle limiting filter. The angle limiting filter is constructed from: a glass substrate of a parallel plate; and a dielectric multilayer film provided on the glass substrate. This angle limiting filter transmits light within a particular wavelength range approximately perpendicularly incident onto the surface, and shields light outside the particular wavelength range and light within the particular wavelength obliquely incident onto the surface.
1. An imaging device for acquiring an image of an object almost in close contact to an image sensor by utilizing light within a wavelength range,
the imaging device comprising an angle limiting filter that includes:
a substrate of a parallel plate which is a colored substrate that transmits light having a longer wavelength than the wavelength range and absorbs light having a shorter wavelength than the wavelength range; and
a dielectric multilayer film (i) which is provided on the substrate, and (ii) which transmits the light approximately perpendicularly incident onto a surface thereof and shields the light obliquely incident onto the surface.
2. The imaging device according to claim 1 , wherein the dielectric multilayer film serves as a band pass filter for shielding light outside the wavelength range and approximately perpendicularly incident onto the surface.
3. The imaging device according to claim 1 , wherein the dielectric multilayer film serves as a low-pass filter for transmitting light that is perpendicularly incident onto the surface and that has a shorter wavelength than the wavelength range and for shielding light that is perpendicularly incident onto the surface and that has a longer wavelength than the wavelength range.
4. The imaging device according to claim 1 , wherein the dielectric multilayer film is provided on each surface of the substrate.