Research Of Confocal 3-D Scanning Method Based On Phase-only Liquid Crystal Spatial Light Modulator

Currently, 3-D scanning to samples is still achieved mainly by using machinery. However, such a method is not suitable for the cases with high requirement such as observing living cells and internal testing for material, due to the mechanical characteristics. On the other hand, confocal microscopy technology is widely used in the fields of 3-D microstructure measurement such as biomedicine. The introduction of conjugate pinholes results in the loss of the field of view. As a result, the 3-D measurement must be performed by combining the confocal scanning and the point-by-point scanning.To achieve confocal microscopy scanning without machinery, the principle as well as the related characteristic of the horizontal scanning and longitudinal variable-focus scanning is analyzed in the project of “Confocal microscopy technology based on 3-D scanning using a liquid crystal spatial light modulator”. On this basis, a confocal microscopy 3-D scanning system using liquid crystal spatial light modulator is designed, the principle of the proposed method is experimentally verified, and the 3-D scanning as well as outline recovery of the microstructure samples is finally achieved by using such a system.The main tasks completed in this project are shown as below.(1) A model of “prism phase distribution” is simulated by using a phase-only liquid crystal spatial light modulator, to achieve the continuous and average deflection of the single beam. The important parameters such as the maximum deflection angle, deflection accuracy and deflection efficiency are researched and analyzed.(2) The principle of longitudinal variable-focus scanning which realized by using a phase-type liquid crystal spatial light modulator is researched, the longitudinal scanning range as well as the scanning accuracy is analyzed. On this basis, a new longitudinal scanning method without machinery, i.e. to achieve longitudinal scanning of multi-focuses simultaneously by using a liquid crystal spatial light modulator, is proposed to enhance the scanning range and efficiency, and its characteristic is researched and analyzed.(3) On the basis of(1) and(2), the 3-D scanning of the incidence beam is achieved using the model of “prism-lens composite phase distribution” simulated by a phase-type liquid crystal spatial light modulator. The scanning accuracy is simulated and analyzed.The experimental platform of beam 3-D scanning is built, in order to experimentally verify the method of the beam 3-D scanning using a phase-type liquid crystal spatial light modulator.(5) The experimental platform of confocal microscopy 3-D scanning is built, to verify the 3-D scanning method with a phase-type liquid crystal spatial light modulator in the confocal microscopy system. The characters of horizontal scanning, longitudinal scanning, and longitudinal scanning with multi-focuses are experimentally researched. Secondly, the 3-D scanning module and the data-process module are programmed by using Lab VIEW and Microsoft Visual C. Finally, the 3-D scanning as well as outline recovery to a microstructure sample is performed by using the proposed method; the parameters of the scanning result are then calculated and analyzed.