Top sellers

Optical Properties of High Resolution Microscopy

No. 1.5 Coverslip-Like Thickness

The thickness of the coverslip is a crucial aspect of imaging quality. The typical thickness of a coverslip is 0.17 mm (170 µm, No. 1.5). Most of the objective lenses used for microscopy are corrected to this special thickness. Thinner or thicker substrates require the use of correction collars on the objective lenses, which then prevent the formation of blurred images by spherical and chromatic aberrations.

The special plastic material (ibidi Polymer Coverslip) that is used in all ibidi μ-Slides, μ-Dishes and μ-Plates provides coverslip optics for high resolution microscopy. The μ-Dishes 35 mm, high, the µ-Slide 2 Well | 4 Well | 8 Well, and the µ-Slide 2 Well Ph+ | 4 Well Ph+ are also available with a coverslip glass bottom.

Compatibility to Immersion Oil

Oil immersion is an important technique that is used to increase the resolution of the objective, up to its physical limit. Placing immersion oil instead of air between the objective lens and the coverslip allows a significantly higher amount of light to be collected by the lens. This, in turn, increases the resolution and the signal-to-noise ratio in microscopic images.

Cell culture chambers for high resolution microscopy need to be compatible with immersion oil. All ibidi μ-Slides, μ-Dishes, and μ-Plates are compatible with a variety of immersion oils. You will find a list of suitable immersion oils in each instruction manual of the ibidi µ-Slides, µ-Dishes, and µ-Plates.

Standard Refractive Index

The refractive index nD of a material measures the speed of light inside that specific material, as compared to the absolute vacuum. The refractive index is often referred to as “optical density”. For optimal microscope images, the refractive index needs to be 1.52. Like glass and immersion oil, the ibidi Polymer Coverslip has a refractive index of 1.52.

Material Refractive Index nD
Air 1.0003
Water 1.33
Glycerol 1.47
Immersion oil 1.52
Glass 1.52
ibidi Polymer Coverslip 1.52

Numerical Aperture

The numerical aperture (NA) of an objective lens summarizes the range of angles over which a lens can collect light. NA is one of the main parameters of an objective lens, which defines resolution and luminous intensity.
The numerical aperture is defined by NA = n sin θ, where n is the refractive index of the medium in which the lens works (e.g., 1.52 for immersion oil) and θ is the half-angle of the maximum cone of light that can enter into the lens.


Material Dispersion / Abbe Number > 55

Material dispersion is defined as a variation in the refractive index, depending on the wavelength. In other words, dispersion is a measurement for chromatic aberrations. The Abbe number summarizes the dispersion into one value. It is calculated from the refractive indices of three different wavelengths. The higher the Abbe number, the better the optical quality for microscopy. A material with an Abbe number larger than 55 is considered to be well suited for high resolution microscopy. The ibidi Polymer Coverslip has an Abbe number of 56 in comparison to D 263M Schott borosilicate glass, which has an Abbe number of 55.


Transmission is a crucial parameter for microscopy. It describes a material’s ability to permit the passage of light through it at specific wavelengths. The more light that is absorbed, the less it can contribute to fluorescence excitation and image acquisition. Unlike normal cell cultureware, which is not transparent in UV light region below 300 nm, the ibidi Polymer Coverslip also permits light transmission in wavelengths below 300 nm.


Low Fluorescence Background (Autofluorescence)

Autofluorescence is a material property that describes the intrinsic fluorescence value of the pure material. The fluorescence signal comes from the material and contributes to the imaging process as noise. This can be annoying when trying to image faint fluorescence signals. Depending on the wavelength and type of material, all materials show some degree of autofluorescence signals.


Material Thickness Refractive Index nD
(589 nm)
Abbe Number
ibidi Polymer Coverslip # 1.5 1.52


Glass coverslip D 263 M # 1.5 1.52


Quartz glass coverslip # 1.5 1.45

Very low

Polystyrene (normal Petri Dishes and culture flasks) Various 1.56


PC Various 1.59


PMMA #1.5 1.49