Design And Study Of Ultra-short Throw Projection Lenses

Compared with other projection technologies,ultra-short focal projection only needs a very short working distance,which not only improves space utilization,but also avoids the problem of obstructions in the ray projection area.Because of this,ultrashort focal projection has become one of the main research directions of projection display technology.The projection lens is important to achieve ultra-short focal projection.Many researchers have done a lot of research,but there are still some problems,such as the difficulty of designing free-form mirror,and the difficulty of controlling the image distortion while obtaining low throw ratio.In this paper,the design of ultra-short focal projection lens was studied.According to the parameters and indexes set by the company after market research,the ultra-short focal projection lens was successfully designed to meet the requirements.The main research contents of this paper include:(1)The relevant research progress at home and abroad is sorted out.Various aberrations in optical design are analyzed,and solutions are proposed.The advantages and disadvantages of several commonly used projection lens structures are compared and analyzed,and the projection lens of this subject is designed with a catadioptric structure.The common parameters of the projection lens are introduced,and the imaging performance index of the projection lens is determined.(2)The parameters of the whole system are analyzed and calculated according to the parameters and indexes formulated by the internship company.Firstly,the refraction lens group was designed.A simple anti-distance structure was selected as the initial structure,and the optimization and improvement method of the structure was developed according to the parameters.On this basis,a refraction lens with good aberration correction has been successfully optimized and designed.(3)A free-form surface construction method that can be used in the design of ultrashort throw projection lenses is proposed.This method improves the constructioniterative design method,and removes a large number of repeated calculations on the basis of the original method.For the free-form surface mirror designed in this paper,the calculation amount of the new method is only one percent of the original method,which greatly improves the construction efficiency.A simple design example of a mirror system proves the accuracy and practicability of the method.According to the new construction method,using the designed refraction lens group as the characteristic light rays,a free-form surface mirror that can be used in the projection system of this article is successfully constructed.This mirror basically corrects the distortion of the system,laying a foundation for the optimal design of the overall system.(4)Combine the separately designed refraction lens groups and reflectors for overall optimization design.Based on the optical basic theory and design principles,the optimization ideas of the optical system are summarized.After a large number of system optimizations and manual adjustments,an ultra-short throw projection lens is successfully obtained.The lens throw ratio is only 0.2,the distortion is less than 2%,and the distortion of the system is controlled while obtaining a low throw ratio.The chromatic aberration is controlled to the size of half a pixel,the MTF value of the full field of view is greater than 0.4 at the cut-off frequency,and the image quality is clear.Subsequently,tolerance analysis of the designed projection lens is carried out to determine that its performance meets the design specifications and product requirements.