Large Area Flexible Optical Film Design Based On Grating Principle

Tactile sensor is capable of sensing external stimuli like the human way.Various tactile sensors based on capacitive,piezoelectric,and resistive mechanisms can mimic the sensing capabilities of human skin as touching,slipping,and temperature.It plays a key role in realizing the high-precision grasping of robot and intelligent prosthetics.Based on the theory of micro-optics including vector diffraction and equivalent medium mechanisms,in this paper we designed a flexible thin film which can response a strain in a micron scale.The research content is as follows:(1)We have deduced the calculation methods of diffraction efficiencies of rectangular arrays,step arrays,subwavelength arrays,and two-dimensional arrays,respectively.(2)We designed a one-dimensional flexible rectangular microarray based on the theory of micro-optics,the effect of the structural factors of the device on the reversed diffraction efficiency was studied.We analyzed the influences of the wavelength incident angles of TE light and TM light on the reverse diffraction efficiency of this rectangular microarray.The results showed that the height of optimal rectangular array was determined to be 0.53?m in a flexible rectangular microarray determined by the period.The optimal duty cycle was 0.5.(3)In this paper,we study the relationship between the inverse first-order diffraction efficiency and the diffraction Angle of the zigzag microarray structure.We use the binary optical process method to analyze the relationship between the efficiency and strain of the first-order diffracted light in a one-dimensional flexible trapezoidal microarray structure.It is found that the diffraction efficiency of reverse diffraction is changed periodically with the compressive strain of the device.The first-order diffracted light was always-9.487° in the period of 4 ?m.(4)We studied the structure of subwavelength rectangular microarray based on subwavelength theory.It is found that the subwavelength flexible rectangular microarray film has no diffractive light without applied strain,the diffraction effect gradually occurred when the tensile strain was more than 1.5 times.The angle of the reverse order diffraction increased with the increasing tensile strain.When the strain reached 1.5 times,the diffraction angle changed from 90° to-83.7°.The results showed that when the tensile strain increased to 7.58 times,the inverse first order diffraction Angle decreased to-16.95°.According to this phenomenon,we can design a microarray film with large strain and diffraction mutation.(5)We analyzed the relationship between the diffraction efficiency and the strain of the microcolumn array in the two-dimensional direction.It was found that this large-area microarray film could simultaneously respond to pressing and stretching.The relationship between the diffraction efficiency and strain of the two-dimensional array is similar to that in the one-dimensional direction.