Lateral Resolution Enhancement Of Confocal Microscopy By Structured Detection Method Based On Spatial Light Modulator

The point detector used in confocal microscopy system makes it possible to produce a "1.4 times" enhancement in the transverse direction over the conventional microscopy. However, the actual pinhole size cannot be infinitely small. In addition, the resolution and SNR influence and control each other in the actual confocal microscopy. In order to satisfy the requirement of SNR, the size of the pinhole is increasing, which leads to a rapid reduction in lateral resolution so that it is almost equivalent to conventional microscopy. Therefore, how to improve the lateral resolution of confocal microscopy with the limited detection pinhole size is the problem that many scholars have been concerned about in the field of confocal microscopy imaging and measurement.In view of the above problem, this paper proposes a new method of lateral resolution enhancement in confocal microscopy by structured detection based on spatial light modulator, making improvements and breakthroughs in the existing method to achieve high resolution and fast imaging in the large pinhole confocal microscopy system. The main purpose and significance of this research topic lies in two aspects. On the one hand, the resolution and SNR will be obtained at the same time in confocal microscopy with the limited detection pinhole size by using the structure detection method. In addition, improving the existing structure detection method of demodulation and reconstruction process will make that the implementation of structure detection method is more simple and easy to operate. On the other hand, a spatial light modulator will be used in system to realize the structure detection process avoiding the rate limiting role of CCD detector. As a result, the detection rate of the system would be effectively improved. The main contents are as follows:Firstly, based on the coherent imaging theory of confocal microscopy, the super resolution principle of the structure detection method is analyzed. Simulation analysis is made on the influence of structural parameters on the resolution characteristics of the system, and the improved structure detection function is obtained; and from the point of view of the system point spread function and the coherent transfer function, the super resolution performance of the structure detection method is simulated and verified.Secondly, the lateral resolution can be promoted to 1.8 times by the introduction of the structure detection method in the confocal microscopy system with the finite size of the pinhole size, which is 1.3 times of the ideal confocal microscopy system. These data are obtained based on resolution evaluation method based on cut-off frequency and FWHM of intensity point spread function。Finally, the experiment platform is designed and set up to verify the theory. The virtually structured detection experimental system is set up to verify the correctness of theory that the new structured detection function can improve the lateral resolution of the system. The structured detection experimental system of the confocal microscopy system based on spatial light modulator is built to verify the realization of lateral superresolution and improvement of detection efficiency. Experimental results show that the method proposed in this paper can achieve a balance between the resolution and the SNR in the actual confocal microscopy system, and the improvement of the lateral resolution 1.6 times in the experiment; at the same time, the spatial light modulator is used to simulate the structure detection function distribution, the effective detection rate promoted to 33 times compared to the virtual form.