The ability to achieve a small spacing between two lenses allows for marking of microscopic objects. The optical axis can be bent at a 90-degree angle, which is extremely useful in space-limited situations, resulting in a mirrored image. When using the optical system, the image may appear blurred or distorted due to the strong effect of irregular prism contours. However, during quality control, by eliminating prisms with stronger contour irregularities, clear images can be obtained even with HR lenses.