| Full-field optical coherence tomography(OCT)is a technique that can distinguish cancerous and healthy tissues in real-time and nondestructively with submicron resolution.Its availability provides a new approach to the diagnosis of malignant tumors.The axial scanning structure in existing full-field OCT needs to be placed in the interferometric section so that the vibration of the mechanical scanning structure can lead to imaging errors.To solve this problem,a full-field OCT using a tunable optical range difference source(TPDS-OCT)was designed to add the axial section scanning to the light source modulation section and also to enhance the system signal-to-noise ratio by using a dualinput Mach–Zehnder interferometric structure.The optical-mechanical design of the interferometric section allows for a smaller aberration of the interferometric structure,which in turn improves the performance of the system.The main work of the paper is summarized as follows:1.The collimated beam spreading part and the imaging part of the interference part of the system were designed separately by using ZEMAX software,and the appropriate initial optical structure was selected during the design process,in which the collimated beam spreading part used the Galileo beam spreading structure,while the imaging optical path used the double telecentric optical path.After the optimization,the aberrations of the system were analyzed,and the data results showed that the system has an image quality close to the diffraction limit for the sample on the objective surface.Then the illumination path was simulated in ZEMAX non-sequential mode,and the simulation results showed that the spot on the object surface was clear and the overall energy distribution was uniform.Finally,the sample is simulated and imaged,and the interferogram is demodulated by the algorithm to obtain the final laminar map,which shows a good demodulation effect.2.the imaging system of TPDS-OCT system was analyzed for tolerance,and the assigned results showed that 90% of the results of the imaging system within the tolerance range met MTF>0.15.In addition,the engineering work such as optical parts drawing and optical system drawing was performed by Auto CAD on the design results of TPDS-OCT system.After that,the ghost image in the TPDS-OCT system was analyzed,and the path and energy data of the secondary ghost image of the imaging optical path were obtained in the sequential mode and non-sequential mode of ZEMAX,respectively,and the experimental data showed that both were insensitive to the ghost image.3.mechanical design on the basis of optical design,by comparing the optional lens barrel material and lens material,titanium alloy was selected as the material of the lens barrel.The thread pitch value in the threaded compression ring was selected depending on the parameters of the optical lens of the system,the acceleration the system has to withstand,etc.The thread pitch was calculated by the formula to be 0.3mm.Then,because the reflector is mounted differently from the general lens,the technique of mounting it on a base plate using a flexible liner and a solid pressure plate was chosen.Finally the overall structure is built up. |
