IR image converter producing visible image - has anisotropic crystal with critical phase matching between right angle and polarised rays

摘要

An image converter changes the frequency of an image in the i.r. range to one in the visible range. It reduces the amount of dispersed light in night vision equipment using i.r. laser scanning. A pump laser (2) operates in the visible or i.r. spectrum. An anisotropic crystal (1) serves as an optical transmission element for the i.r. signal and pump laser light. A fitler (4) passes the frequency of the converted light. A detector is provided for the latter. Lenses and/or reflectors (5) are provided to form a collimated beam and forms the i.r. signal and laser light as well as to form visible image. A critical phase matching is made between the rays polarised in the crystal and a right angle in the crystal (1).