refractive indices vs refractive indexes

Some examples from the web:

• Different refractive indices lead to spherical aberrations and geometrical distortions of the structures.
• Choose objectives with a motorized correction collar to simplify adaption to different refractive indices.
• This performance is optimal when the refractive indices of the sample and the intervening media match.
• The following chart lists the refractive indices for 143 varieties of gemstones, arranged in descending order.
• Measuring the refractive index is one of the first steps in identifying a gemstone, though some gemstones have similar refractive indices and additional tests are required for a definitive identification.
• 'Dielectric layers' are coatings constructed of multi-layers of insulator materials in which the interference properties of a design composed of materials of various refractive indices are used to reflect, transmit or absorb various wavelength bands.
• The higher the numerical aperture of the objective and the deeper the structures of interest inside the sample, the more important it is to match the refractive indices of the sample and the immersion medium.
• Refractive indices of some important immersion media
• Mismatches in the refractive indices cause deterioration of the point-spread function, geometric distortion, and spherical and chromatic aberrations.
• Other gemstones - in fact, most - are doubly refractive; they have two different refractive indices.
• The Water Immersion Microdispenser counteracts evaporation of water as an immersion medium during long term match the refractive indices of living samples, the dedicated 63x glycerol objective is also optimized for 37ºC. Maintain the sharpest images with ease.
• The refractometer used must be fitted with a scale giving:- either percentage by mass of sucrose to 0,1 %,- or refractive indices to four decimal places.
• Refractometer enabling refractive indices to be measured in the range 1,330 to 1,346.
• They are perfectly homogenous, i.e. normally without bubbles or unevenness, and have refractive indices and scattering properties unusual in other types of glass.

Some examples from the web:

• Circa 1890, the Viennese mineralogist F. Becke indicated that, when one defocused the thin section under the microscope, the direction of displacement of a luminous fringe in contact with two contiguous minerals is done according to the relative value of their refractive indexes.