Measurement instrument detects focus states from correlation between two images formed by light passing through different objective pupil areas to separate semi-transparent surface areas

摘要

The device has a telescope tube with an objective and eyepiece, an alignment system between the objective and eyepiece with a semi-transparent surface carrying a beam divider prism and a phase difference focus detector that receives light passing through the semi-transparent surface to detect focus states from the correlation between images formed by light passing through different objective pupil areas separate semi-transparent surface areas. The device has a telescope tube (10) with an objective lens (11) and an eyepiece (14) for sighting an object, a porro prism alignment system (12) between the objective and eyepiece with a semi-transparent surface carrying a beam divider prism and a phase difference focus detector (50). The detector receives light passing through the semi-transparent surface to detect focus states from the correlation between two images formed by light passing through different pupil areas of the objective to separate areas of the semi-transparent surface at the same angle of incidence.