A cover slip or cover glass is a thin flat piece of transparent material, usually square or rectangular, about 20 mm (4/5 in) wide and a fraction of a millimeter thick, that is placed over objects for viewing with a microscope. The object is usually held between the cover slip and a somewhat thicker microscope slide, which rests on the microscope’s stage or slide holder and provides the physical support for the object and slip.
Cover slips are manufactured from optical quality borosilicate (Schott D 236 M glass) to the highest standards and are optically clean and ready for use. Schott D 236 M glass is Water White glass with very low iron content. Its glass composition assures an excellent resistance to chemical attack. The Schott D 263 M glass is used as cover cover slips in microscopy for medical, biological and research work. The excellent UV absorption properties make this glass an ideal material for use in fluorescence microscopy.
- Virtually colorless
- Excellent internal glass quality with very low levels of inclusions, striations, streaks, and bubbles.
- High spectral transmission.
- Excellent flatness.
- Resistant to chemical attack.
- Refractive index finely tuned for microscopes.
- Most microscope objectives are corrected for a cover glass thickness of 0.17mm, corresponding to #1.5 cover glasses.