Optical instrument

摘要

An optical instrument such as a binoculars has an eyepiece lens unit detachably mounted on an eyepiece mount and comprising an eyepiece lens assembly including an eyepiece lens and an image intensifier tube assembly separably coupled to the eyepiece lens assembly. The image intensifier tube assembly includes an image intensifier tube having a light-sensitive surface lying at the focal plane of the objective lens and a phosphor screen lying at the focal point of the eyepiece lens. When the optical instrument is used to enable the user to see a dark object, the eyepiece lens unit with the eyepiece lens assembly and the image intensifier tube assembly coupled together is attached to the eyepiece mount. For the user to see a bright object, the image intensifier tube assembly is detached from the eyepiece lens assembly, and the eyepiece lens assembly is attached directly to the eyepiece mount.