Tissue Thickness Analyzer

Project goal: To design and implement a tool for measuring the thickness of histological tissue sections on a microscope slide. Tissue samples in a given protocol are processed in an identical fashion, but their thickness might vary. This inconsistency could influence the final staining results and, therefore, the resulting diagnosis. Mitigating this inconsistency requires determining variations in thicknesses by directly measuring the samples before they are processed. The design uses near-infrared reflectance confocal microscopy. A near-infrared laser is focused on the tissue section as it moves through the beam. Movement is tracked using a differential micrometer paired with a rotary encoder. As the index of refraction changes, particularly at the top and bottom interfaces of the section, the laser is reflected onto a photo-diode. Microscope objectives and a spatial filter are used to reduce noise, increasing sensitivity and signal-to-noise ratio. The thickness of the section is calculated by tracking how far the stage has moved between the strong signals corresponding to the bottom and top of the section.