Continuously Variable Spatial Frequency 3D Image Lithography Technology And Application

3D color hologram is applied to the production and testing of the safety and new-style printing material due to the stereoscopic effect.At present,the main technologies for fabricating color hologram include laser holography,laser direct-writing,electron beam lithography and laser interference lithography.The application of the traditional lithography is limited due to the strict environmental condition.As the limitation of the resolution,the view angle of 3D image is narrow by the laser direct-writing method.The large data volume,low efficiency,small format size and high cost,limit the application of the electron beam lithography method.Laser interference lithography is an efficient method for fabricating color holography by combining parallel exposure and laser direct-writing.As the modulation of the space-frequency and orientation is uncontinuous,the current lithography method has the defects of color deviation,weak 3D effect and small field of view.A continuously variable spatial frequency laser interference lithography system is proposed in this paper.By continuously modulating the output light field,the space-frequency and orientation of grating pixels in the 3D image can be continuously modulated,resulting to strong 3D effect and large field of view.Compared to the electron beam lithography,the data volume is greatly compressed(over 10000 times)by the interference lithography Firstly,the principle of dot-matrix hologram is analyzed by diffraction optics theory.The period and orientation angle of grating pixels are theoretically calculated for the basic analysis of the image coding.According the holographic theory,the ultraviolet continuously modulated space frequency lithography system is proposed and elaborated.The principle of the light field of this system is discussed.Then,the 3D image output is researched,including the micro-nano structures of the monochrome and color image,the calculation of the image coding,the capture of 3D image,image processing,and software.Lastly,the correlation theories are demonstrated through series of experiments.Series of single frequency and single orientation are fabricated using the proposed laser interference lithography system,and the experiment value is consistent with the theoretical value.The continuously modulated output light field has been demonstrated by fabricating a single frequency 3D image and a coaxial Fresnel lens.A series of 3D images were fabricated by this system.The apparent and colorful 3D effects and the large FOV are achieved,which satisfied the design requirements.As a result,the proposed lithography system can provide an effective mean for fabricating large size 3D color hologram,and is appealing to the market.Under the background of the current 3D display development,this technology has an important application and prospect.