IMAGE PICKUP DEVICE
An image pickup comprising objective lens for forming an optical image of an object, a prism for turning a light path of light rays from said object, and a photoelectric solid-state image sensor for converting the optical image to electric signals. The prism has a plane of incidence for admitting the light rays from an object, a plane of reflection for turning a light path toward the solid-state image sensor, a plane of egression through which the light rays leave prism on the way to the solid-state image sensor, and an infrared cut coating in the form of an optical multi-layer coating deposited either on the plane of incidence or on the plane of egression for cutting off infrared components of incident light.
1 . An image pickup comprising an objective lens for forming an optical image of an object, a prism for turning a light path of light rays from said object, and a photoelectric solid-state image sensor adapted to convert said optical image to electric signals, characterized in that said prism comprises:
a plane of incidence for admitting light rays from said object, a plane of reflection for turning a light path of said light rays through a predetermined angle toward said solid-state image sensor, and a plane of egression through which said light rays leave the prism on the way to said solid-state image sensor; and
an infrared cut coating in the form of an optical multi-layer coating deposited either on said plane of incidence or on said plane of egression of the prism to cut off infrared components of incident light.
2 . An image pickup as defined in claim 1 , further comprising an ultraviolet cut coating deposited either on said plane of incidence or on said plane of egression whichever has no infrared cut coating, cutting off ultraviolet components of incident light by said ultraviolet cut coating.
3 . An image pickup as defined in claim 1 , wherein said prism is in the shape of a triangle pole having three lateral planes to function as said plane of incidence, plane of reflection and plane of egression, respectively.
4 . An image pickup as defined in claim 1 , wherein one or a plural number of lens elements are positioned between said prism and said solid-state image sensor.
5 . An image pickup as defined in claim 1 , wherein said infrared cut coating is constituted by an optical multi-layer coating formed by alternately laminating a high refractivity layer of TiO 2 and a low refractivity layer of SiO 2 up to approximately 50 layers in total.
6 . An image pickup as defined in claim 2 , wherein said ultraviolet cut coating is constituted by an optical multi-layer coating formed by alternately laminating a high refractivity layer substance selected from TiO 2 and Nb 2 O 5 , and a low refractivity layer of SiO 2 up to approximately 40 to 50 layers in total.