Cassegrain capable of eliminating parasitic light and modified imaging system thereof

Abstract

The invention discloses a cassegrain with a parasitic light eliminating device and a modified imaging system thereof. The cassegrain comprises a secondary mirror of which reflecting surface is convex surface, a primary mirror of which reflecting surface is concave surface, a primary mirror hood and a secondary mirror hood sleeved on the external edge of the secondary mirror, wherein the primary mirror and the secondary mirror have a common optical axis, the primary mirror is provided with a centre round hole, the primary mirror hood is arranged at the centre round hole of the primary mirror, an additional light-eliminating cylinder is arranged between the secondary mirror hood and the primary mirror hood and is used to prevent light to penetrate through the centre round hole between the secondary mirror hood and the primary mirror hood and arrive on the image surface, the space formed by the cylinder wall of the additional light-eliminating cylinder is shaped like cone, the axis and the optical axis of the primary mirror or the secondary mirror are overlapped, and the extended line of the generatrix of the additional light-eliminating cylinder penetrates through the focus of the primary mirror. The light-eliminating cylinder is just added in the cassegrain of the invention so that the light leakage of the system is completed eliminated, the weight and volume of the entire system are greatly reduced and the load is reduced; and the cassegrain has strong applicability and simple structure and is convenient to design.

Description

technical field [0001] The invention relates to a Cassegrain and its improved imaging system, in particular to a Cassegrain with a stray light eliminating device and its improved imaging system. Background technique [0002] The Cassegrain system is a coaxial reflective system that can obtain a relatively long focal length with a relatively short overall length. It consists of two reflectors, called the primary mirror and the secondary mirror, such as figure 1 shown. The primary mirror is a paraboloid or an approximate paraboloid, and the secondary mirror is a hyperboloid. The light from the object side is first reflected by the primary mirror, then reflected by the secondary mirror and passes through the central opening of the primary mirror to reach the image plane for imaging. [0003] Such as figure 1 The shown Cassegrain system can only perfectly image the on-axis light, and the imaging of the off-axis light will have obvious aberrations even if the field of view is ...

AI Technical Summary

Problems solved by technology

due to L 1 , L 2 and L 3 Both require corresponding fixed structures, making the structure more complicated

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