Serveral Optical Enginee Key Techniques In The LCoS Pico-project

The wave-front coding defocus insensitive projection lens has great relation with the cubic phase plate.In the coherent imaging system,quadratic phase term also has great influence on the image distribution,we think these two terms may have some relations with each other.Because of this,in this paper,with the strict integration analysis,we expressed the coherent imaging system as a convolution of the quadratic phase term(QPT)modulated GOPI and the PSF.Then the QPT elimination conditions are derived according to the convolution characteristic of the quadratic phase cosine and sine with the PSF.Two convolution imaging conditions are derived.We call these two convolution imaging condition boundary restricted condition and the Fresnel number restricted condition respectively.Simulations show the correctness of these two restricted conditions.The research will further deepen the understanding of the coherent imaging analysis and wave-front coding research.Fly-eyes lens is an integral element commonly used in the illumination system.For the projection illumination system,the direct optimization method based on the imaging optical design software is first realized.The multiplex conjugate imaging relationship is pointed out between the illumination zone and the incident facet of the first surface of the fly-eyes lens’ different sub-lens.The multi-configuration system is figure out to illustrate the multiplex conjugate imaging relationship.The fly-eyes lens and relay lens parameters can be directly optimized when the illumination size and max incident angle of the illumination zone are specified,which is much more easy and accurate to design than that of the traditional non-imaging optimization method.Simulations show that this method can give excellent illumination result and fast design period.The validity of the method is also proved by the experiment with the proposed method.Based on our light pipe polarization recovery idea firstly proposed in the world,we discussed the biased LED illuminated light pipe angle segmentation and its virtual image array principle.The principle is then verified with the imaging software with none-sequential surface configuration.The light pipe length and size is then calculated according to the biased LED position,size,radiation angle and CF-LCoS size.Then the light pipe,front imaging lens,the intermediate image plane PCS,the integration lens and the PBS is inputted into the imaging software for optimization.The system then is simulated with the none-imaging software for locating the intermediate image distribution to determine the PCS structure.The PCS is then input into the none-imaing software again to simulate for the uniform and efficiency illuminations on the CF-LCoS and screen.A CF-LCoS projection system is finally designed with the white LED.The optical engine can output light flux of 17.6 lumens with 93%irradiance uniformity.The new system greatly enhances the light efficiency of the LCoS micro projection system.This research enriches and improves the light pipe application in the projection lighting system.Finally,a projection lens with long depth of field for the CF-LCoS projector is developed to satisfy the new requirement.We first design the projection lens with the traditional optical design software to let it project the image to the average projection distance.For example,if the lens is designed with in the range of 0.65-2.0m,then about 1.0m is selected as the preliminary projection distance.After the lens(with a 3mm plane plate at the stop surface)is optimized with the CODE V in this distance,the plane plate is replaced with cubic phase plate.Then the lens is optimized again(the phase plate parameter varied for optimization)to get the final lens.In the new optimization,the resolution should be 3 times of the real resolution according to the LCoS resolution.This new optimized lens has the same MTF or PSF for different fields between 0.65 and 2m projection distances,this ensures the high resolution with no focus operation.Because of the MTF satisfies the CF-LCoS requirement between the distance of 0.65 to 2m,no resolution is damaged and also no focus operation is needed in this effective projection distance,thus no mechanical focus system is needed.The main contributions of this paper are listed as below:1)Expressing the coherent imaging system as a convolution of the quadratic phase term(QPT)modulated GOPI and the PSF and derive the QPT elimination conditions called the boundary restricted condition and the Fresnel number restricted condition respectively;2)The fly-lens system paramters calculation equations for the large incident angle are derived.Optimization of the fly-eyes lens and relay lens parameters with the imaging software which is much more easy and accurate to design than that of the traditional non －imaging optimization method for the large incident angle fly-eyes system.3)Biased LED illuminated light pipe’s angle segmentation and its virtual image array formed principle are given first.The principle is then verified with the imaging software with none-sequential surface configuration.Several ligt pipe polarization recovery systems are provided;4)With the inverse idea which is different with those which only use the wave-front coding technique in imaging application,the WFC is used for the defocus insensitive projection lens design which greatly simplifies the CF-LCoS optical Enginne.