GB/T 44276.1-2024 Microscopes - Cover glasses - Part 1: Dimensional tolerances, thickness and optical properties
1 Scope
This document specifies requirements for dimensional tolerances, thickness and optical properties for microscope cover glasses used for transmitted light microscopy in the visible spectral range (400 nm to 760 nm).
This document applies to the design, manufacture, and application of microscope cover slips.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 8036 Microscopes - Immersion liquids for light microscopy
Note: GB/T 26600-2024, Microscopes - Immersion liquid for light microscopy (IEC 8036:2015, MOD)
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
——IEC Electropedia: available at http://www.electropedia.org/
——ISO Online browsing platform: available at http://www.iso.org/obp
4 Requirements
4.1 General
All media that are located between the specimen and the microscope objective are in their optical effect part of the objective. Such media are usually cover glasses and immersion media. Immersion media are defined in ISO 8036; their refractive index shall be taken into account for the selection of the cover glass.
Microscope objectives, unless equipped with correction collars, are designed for a specific immersion medium (e.g. air, oil or water) and cover glass thickness. The design thickness is t = 0.17 mm, unless otherwise marked on the objective.
When using microscope objectives with high numerical aperture, deviations from the nominal cover glass thickness leads to severe optical aberrations, mainly spherical aberration.
The refractive index of the cover glass material needs to be specified for a broad spectral range to maintain good chromatic correction. This is achieved by specification of the refractive index, ne, for a reference wavelength (λe = 546.07 nm) near the maximum of the eye’s spectral sensitivity and the corresponding Abbe number, νe.
4.2 Dimensional tolerances for thickness
The thickness tolerances of cover glasses shall be in accordance with Table 1.
In addition to the thicknesses given in Table 1, cover glasses are available in other thicknesses. These can be used for certain applications or in combination with objectives specifically designed for such non-standard cover glasses. However, it shall be pointed out that the highest optical quality may not necessarily be obtained with such cover glasses, when using objectives of high numerical aperture.
Annex A provides guidelines for the selection of cover glass No.1 ½ and No.1 ½ H with objective numerical aperture values in combination with common immersion media.
4.3 Dimensional tolerances for length, width and diameter
The limiting tolerances for nominal length, l, and width, w, for rectangular cover glasses (Form A) as shown in Figure 1 or diameter, d, for round cover glasses (Form B) as shown in Figure 2 are ± 0.5 mm.
Typical dimensions for rectangular and round cover glasses are given in Table B.1.
4.4 Optical properties
Cover glasses shall have the following optical properties:
Principal refractive index: ne = 1.5255 ± 0.0015
Abbe number: νe = 56 ± 2
Note: The principal refractive index, ne, is the index of refraction for light of wavelength λe = 546.07 nm (green Mercury e-line). This wavelength is located close to the maximum spectral sensitivity of the human eye and is commonly used as a reference wavelength for optical computations (see ISO 7944).
The Abbe number, νe, is computed according to Formula (1):
GB/T 44276.1-2024 Microscopes - Cover glasses - Part 1: Dimensional tolerances, thickness and optical properties
1 Scope
This document specifies requirements for dimensional tolerances, thickness and optical properties for microscope cover glasses used for transmitted light microscopy in the visible spectral range (400 nm to 760 nm).
This document applies to the design, manufacture, and application of microscope cover slips.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 8036 Microscopes - Immersion liquids for light microscopy
Note: GB/T 26600-2024, Microscopes - Immersion liquid for light microscopy (IEC 8036:2015, MOD)
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
——IEC Electropedia: available at http://www.electropedia.org/
——ISO Online browsing platform: available at http://www.iso.org/obp
4 Requirements
4.1 General
All media that are located between the specimen and the microscope objective are in their optical effect part of the objective. Such media are usually cover glasses and immersion media. Immersion media are defined in ISO 8036; their refractive index shall be taken into account for the selection of the cover glass.
Microscope objectives, unless equipped with correction collars, are designed for a specific immersion medium (e.g. air, oil or water) and cover glass thickness. The design thickness is t = 0.17 mm, unless otherwise marked on the objective.
When using microscope objectives with high numerical aperture, deviations from the nominal cover glass thickness leads to severe optical aberrations, mainly spherical aberration.
The refractive index of the cover glass material needs to be specified for a broad spectral range to maintain good chromatic correction. This is achieved by specification of the refractive index, ne, for a reference wavelength (λe = 546.07 nm) near the maximum of the eye’s spectral sensitivity and the corresponding Abbe number, νe.
4.2 Dimensional tolerances for thickness
The thickness tolerances of cover glasses shall be in accordance with Table 1.
In addition to the thicknesses given in Table 1, cover glasses are available in other thicknesses. These can be used for certain applications or in combination with objectives specifically designed for such non-standard cover glasses. However, it shall be pointed out that the highest optical quality may not necessarily be obtained with such cover glasses, when using objectives of high numerical aperture.
Annex A provides guidelines for the selection of cover glass No.1 ½ and No.1 ½ H with objective numerical aperture values in combination with common immersion media.
4.3 Dimensional tolerances for length, width and diameter
The limiting tolerances for nominal length, l, and width, w, for rectangular cover glasses (Form A) as shown in Figure 1 or diameter, d, for round cover glasses (Form B) as shown in Figure 2 are ± 0.5 mm.
Typical dimensions for rectangular and round cover glasses are given in Table B.1.
4.4 Optical properties
Cover glasses shall have the following optical properties:
Principal refractive index: ne = 1.5255 ± 0.0015
Abbe number: νe = 56 ± 2
Note: The principal refractive index, ne, is the index of refraction for light of wavelength λe = 546.07 nm (green Mercury e-line). This wavelength is located close to the maximum spectral sensitivity of the human eye and is commonly used as a reference wavelength for optical computations (see ISO 7944).
The Abbe number, νe, is computed according to Formula (1):
