Zoom Maksutov-Cassegrain Telescope System Design

Based on the requirements of system and designing principles of Maksutov-Cassegrain telescope objective and zoom eyepiece, a zoom Maksutov-Cassegrain telescope system with small size is designed. The system's visual magnification is 25～75. The full-field angle of objective is 2.14°, the focal length is 750mm, and the clear aperture is 75mm. The full-field angle of eyepiece is 50°, the focal length is 10mm～30mm, the F/# is 10, and the eye relief reaches to 14mm. This system includes a zoom eyepiece, a fix-focus objective and a Schmidt roof prism. Zoom eyepiece is adopted in zoom telescope especially in refracting-reflecting telescope widely. What's more, with the development of zoom optical system theory and optical manufacturing technology, image quality of zoom lens has already achieved the level of fix-focus lens. In order to reduce the cost, all optical surfaces of this system are spherical. A meniscus lens and a cemented lens are used in objective to correct the aberrations. A structure with no rear fixed group and inside-image is adopt into the eyepiece to shorten the length of system and increase eye relief. The zoom curve is fitted by using the relative program. A 25～75 times visual magnification is obtained through the zoom eyepiece and objective. And each aberration is corrected well. As a result, a Maksutov-Cassegrain telescope with small size and high cost-performance is obtained.