Microscope Slides and Cover Glasses

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).

3 thoughts on “Microscope Slides and Cover Glasses”

  1. I am wondering if the microscope slide for use with fluorescent microscopy is the same as used in normal inverted microscope or are there any specific brand?

    1. I would say that it is not the microscope type which determines the precise coverglass thickness to be used, but the technique which you intend to utilize. For fluorescence microscopy utilizing non-visible light excitation (e.g. UV excitation) or detection of non-visible light (e.g. IR), special coverglasses would need to be used – calcium silicate/fused silica coverglasses being used for UV excitation, for instance.

  2. Correction to my previous post – it should read coverglass type, rather than coverglass thickness. Coverglass thickness is influenced by the type of specimen, its preparation methods, the objective lens used, irradiating source employed, etc.

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