Microscope Slides and Cover Glasses
Found in: Accessories, Buying Advice, Microscopy Basics


This post gives an overview over common microscope slides and cover glass standards.

Microscope slides carry the specimen to be observed. Microscopic slides generally have a thickness of 1-1.5 mm.

A variety of different standards exist:

  • Standard slide: 26 x 76 mm
  • Geological slide: 75 x 50 mm
  • Petrographic slide: 46 x 27 mm
  • Thin sections slide: 48 x 28 mm

Microscope glass slides may be modified in a variety of ways:

  • They may have a central indentation to carry several drops of liquid.
  • They may have a frosted side to allow for easier writing with a marker.
  • They may have polished corners to reduce the possibility of injury due to sharp corners.

Cover glasses (cover slips) exist in a wide range of different sizes, square, round, rectangular. Common sizes include:

    • 18x18mm
    • 20x20mm
    • 22x22mm
    • 24x24mm
    • various rectangular sizes up to 24x60mm to cover nearly the whole slide.

Choose a cover glass that corresponds to the size of the specimen and the slide. The thickness of the cover glass is important, as it has a significant impact on the resolution of the image. The thickness should correspond to the thickness indicated on the objective lens. In many cases, the cover glass is 0.17mm thick, but there is often a small variation even in the same batch. For critical purposes, it may be necessary to measure the thickness of the individual cover glasses to find one close to the desired thickness (use a vernier caliper to determine the thickness).


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