Cover glass is a thin, flat piece of transparent glass or plastic placed over a specimen on a microscope slide. It protects the sample, keeps it flat, and improves optical clarity for microscopic examination. Cover glasses come in standard sizes (e.g., 22 × 22 mm, 18 × 18 mm) and are essential in biology, pathology, cytology, and educational labs when preparing wet mounts or stained slides.
They help prevent damage to microscope objectives, reduce sample evaporation, and support consistent, high-quality imaging of cells, tissues, and microorganisms under a light microscope.