Pixel dislocation correction method for a laser confocal scanning microscope through the nonlinear triangular wave driving mode and square wave index reconstruction

The reciprocate scanning scheme of two-dimensional galvanometers is widely used in laser confocal scanning microscopes with high speed. However, the equal interval acquisition of an analog digital acquisition card (AD) and the unequal change of the galvanometer's scanning speed will cause the dislocation of pixels and distortion of the reconstructed image. Meanwhile, the movement properties of the galvanometers in the edge of the scanning area are complex, which will increase the difficulty of segmenting the collected one-dimensional data stream the AD collected into row data of a two-dimensional reconstructed image. Therefore, how to timely and accurately segment the one-dimensional data stream the AD collected into the row data of two-dimensional reconstructed image is not only the key to solve image distortion of a laser confocal scanning microscope with high speed but also the prerequisite to improve the accuracy of row data dislocation correction. A driving mode based on the nonlinear triangular wave and a dislocation-correcting method using a square wave index are proposed. Namely, on the basis of the galvanometer's scanning analysis, the equation of a nonlinear triangular wave driving voltage is established, and the switching frequency of the Y-galvanometer's driving voltage is obtained by calculating the collected switching frequency of the X-galvanometer; thus, the uniformity of the galvanometer's scanning trajectories is secured. Finally, the row segmentation flag pulse is first introduced into the one-dimensional data stream the AD collected, and the square wave index is used to segment the collected data, which means the one-dimensional data stream can be segmented timely and accurately via hardware method. Meanwhile, the pixel dislocation can be corrected. The experimental result shows that, compared with the Nikon A1R+ confocal microscope, the proposed method can effectively correct the pixel dislocation, and the position coincidence error is less than 0.7%. The proposed method will be helpful to improve the image quality of a laser confocal scanning microscope with high speed. (C) 2021 Optical Society of America

Automated summary

This paper proposes a method based on a nonlinear triangular wave driving mode and using a square wave index for pixel dislocation correction in laser confocal scanning microscopes with high speed. By establishing the equation for the nonlinear triangular wave driving voltage and calculating the switching frequency of the Y-galvanometer's driving voltage based on the collected switching frequency of the X-galvanometer, the uniformity of the galvanometer's scanning trajectories is ensured. Introducing a row segmentation flag pulse into the one-dimensional data stream collected by the AD, and using the square wave index for data segmentation, enables timely and accurate row data segmentation through hardware methods, while correcting pixel dislocation.