| Projection display technology is an effective way to achieve large scree n display.The rapid development of projection display technology and science,is greatly driving and igniting the demand of the projection display products.In the view of technique level,besides high resolution,high brightness and large screen,the miniaturization direction is also an important feature of the projection display system.However,micro projection system is drawing more and more attentions and adopted for the usage of business,official applior home appliance,due to the advantages of compact size,portable convenience and smart linkage to other intelligent equipments,micro projection display has been seen as a vital component of home theater system.In addition,when digital light processing(DLP)devices was adopted in combination with LED light sources,micro projection display brings with better issues in high reso-lution,brightness and high contrast...The LED light source is collimated and uniformed with the free-form-surface TIR lens.The projector is miniaturizated to meet people's simple and portable requirementsAt first,a set of asymmetric and zoomable lens was successfully designed with the large aperture,and they consist of three groups of lens components.The lens could obtain the high-quality imaging and beam constraints.The parameters: the object-space aperture,F#1.2(<1.4),the focal length 28~33mm,and 3× smoothly zoomed optical amplification.The whole system is 300 mm in total length and constraints the exit beam within an adjustable wide range of 3 °~ 30 °.The optimal MTF plot of the system lies above the minimum limit of 0.4,and the light utilization efficiency reaches more than 40%.The lens uses the conventional materials and spherical light distribution,which could be used as a standardized optical module.Secondly,the DLP micro-projection display optical system was analyzed,and the imaging lens and illumination of the projector were designed separately.By means of non-spherical structure,the high quality of imaging was obtained.As for the lighting section,a single free-form surface TIR lens replaced the multi-lens element collimation design.Based on the corresponding relationship between the target light source and the illumination surface,the differential equations were deduced according to the law of snell.The solution was obtained in the environment of Matlab.The calculated data points formed the free curve under the Pro / Engineer software.Better collimation effect was reached by simulating and analyzing in the Tracepro.Meanwhile the spatial volume of the system minimized and the efficiency of light energy utilization was improved.In order for the best feature of the micro-projection system,the imaging lens and lighting section were simultaneously integrated into the Lighttools software and the n simulated or optimizated.At last,the characteristics of freeform surface optical components were introduced.Then its mathematical expression and design ideas are analyzed.The optical design process of helmet display system with the freeform surface(FFS)prism is analyzed in detail,the FFS prism was in hence designed.Through the comparison between the FFS prism and the traditional rotational symmetry structure,it indicated that the free surface is playing more and more important role in the optical design. |
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