| Immersive head mounted display(HMD)technology is a branch of virtual reality(VR)technology,which is to use the head mounted display optical system to send the digitalized images generated by computer and output by image source into the user’s field of vision and use this method to achieve the simulation of a specific environment.Immersive head mounted display technology has the advantages of large field of view,low power consumption,wearable,modularized,stereoscopic display,High degree of customization and so on.Since its appearance,it has been widely concerned,and has gradually become a representative of the new generation of display technology.It has been widely applied in many areas,especially in the field of astronaut ground simulation training in manned spaceflight.The use of immersive head mounted display equipment(HMD equipment)in the ground simulation training of astronauts can reduce the cost and risk of training under the premise of ensuring the quality of the training.Generally believed that the HMD device for astronaut simulation training needs high resolution and large field of view,at the same time,it is also necessary to meet the requirements of the wearable equipment for lightweight.How to balance the complexity and the performance of the system has become the main problem that must be faced in the development of HMD equipment.In order to solve this problem,we developed a high-performance HMD device that can be applied to astronaut simulation training,and promote the development of virtual reality head display technology.In this paper,under the support of “Research on space station orientation and interactive virtual training technique(B1720132001)"of national defense basic research funding,combined with the specific conditions of application,the key technologies of immersion head display optical system have been comprehensively studied in terms of optical system design,performance evaluation,tolerance analysis and performance detection methods.is in-depth studied,the main research contents and are as follows:1.The development process,main uses and research status of virtual reality technology and head mounted display device are summarized,and a summary of the development trend and the influence of its key technologies on their performance is given.Based on the aberration theory of the large field of view optical system,the aberration correction characteristics of multi degree of freedom optical elements,such as aspherical and diffractive optical surface,are theoretically analyzed and demonstrated.At the same time,the main performance parameters of the immersion head display equipment is analysis in detail.2.Comparative analysis of the coaxial transmission structure of some typical eyepiece.According to the comparative analysis of the results,first of all,based on the RKE wide-angle eyepiece structure,with a resolution of 1920×1080 SHARP display as the image source,and one kinds of design scheme for high performance HMD optical system is designed.Then,on this basis,the flexible images with different complexity is introduced to improve the system,so as to the other three kinds of HMD optical system based on flexible display design screen are designed.The all of four optical schemes are four groups and eight pieces of optical structure.The monocular diagonal field of view reaches 120 degrees,which has the advantages of high field MTF value of view field,low chromatic aberration and small distortion.Finally,a comprehensive comparative analysis is made for the four design schemes.The analysis results show that the design scheme of the traditional screen optical system can meet the requirements of index.Compared with the traditional image plane,the flexible display mask has a better role in simplifying the system,correcting distortion and field curvature.The design schemes and comparative analysis results of the four optical systems provide an example reference for the implementation of high performance HMD optical system and the wide application of flexible display in HMD optical system.3.Refraction expression and the principal point expression of eye optical model are derived.According to the analysis result and the comparison result of five kinds of eye model advantages and disadvantages,established the "eye-HMD eyepiece" effect analysis model based on Escudero Sanz model eye for the first time.And by using the model to analyze the actual situation of the traditional human screen HMD optical system design of the effect on the effect of its use.The method provides a more objective evaluation of the actual effect is HMD.According to the analysis results,we put forward the idea of adding eye tracking system in HMD equipment and adjusting the image plane in time with servo control system,in order to eliminate the influence of human eye movement on the use effect of HMD.The "human eye-HMD eyepiece" model analysis method provides a more objective analysis and evaluation method for the actual use effect of HMD optical system.4.The sources of errors in most optical systems are discussed,especially the sources of the surface errors of high aspheric surfaces.Based on this,the tolerance analysis of the traditional screen HMD optical system is carried out.First,the tolerance analysis of regular components in the traditional screen HMD optical system is completed by using ZEMAX software.Then,the analysis method of high aspheric surface accuracy in the traditional screen HMD optical system is completed by using ZEMAX combined with MATLAB programming analysis method.The analysis results show that the traditional screen HMD optical system designed in this paper is a medium precision optical system,and has certain manufacturability,which lays the foundation for the production and processing of the system.5.The performance of detection method for HMD optical system are studied in this paper,starting from the basic definition of performance parameters to be measured,according to the existing conditions of the laboratory,with HMD optical system’s own characteristics,proposed the performance parameters of the HMD optical system testing method based on CCD image capture.By using this method to test the performance of HMD optical system was developed the.The test results are in good agreement with the nominal value,that is,the correctness of the test method is verified,and the performance of the developed HMD equipment is excellent. |
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