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Digital photography: Optimising image quality using test targets

To optimally adjust the microscope settings and to optimise resolution, focus and planarity, we recommend using test targets.

Shown in the image: THORLABS USAF 1951 1x test target

The test target is a glass slide with a pattern of bars and lines of different sizes, which are plated onto the glass substrate. These can be used for fine-tuning the microscope for optimal performance and assessing / optimising image quality. The structured lines, which become progressively smaller, are also an effective way to verify the resolution capability of the microscope. 

For conventional laboratory microscopes, we strongly recommend using test targets covered with cover slips. The USAF 1951 1x test target shown above has a circular, elevated area, which is where the circular cover slip is glued in place. This section matches the standard thickness/height of a glass slide with a cover slip, which is the calibration standard for most laboratory microscope objectives and produces the best image quality.

Shown in the image: a larger test target without cover slip, designed for use with microscopes that have a larger object field of view, such as stereo microscopes or LM macroscopes.