The mask contains patterns to generate both the Gaussian and Bessel light sheets. The area surrounded by red rectangles can transmit light, while the rest of the mask blocks the light. The patterns are organized in pairs, with that for Bessel light-sheet generation on the left and that for Gaussian light-sheet generation on the right. There are in total 13 × 13 patterns for each mode. The width of the patterns ranges from 0.7 mm to 1.0 mm from left to right. The patterns for Bessel beam generation have gaps (light blocking area) in the center, with the width of this gap ranging from 0.2 mm to 0.5 mm from top to bottom. The photomask was designed so that we could have Gaussian light sheets and especially Bessel light sheets with different characteristics. The pattern with a width of 0.825 mm and a gap of 0.30 mm was used for the Bessel beam generation in this study.