The wavelength filters used in the DHM® have a minimal dependence on temperature. For instance, changes on the transmission wavelength due to a change of temperature of 10°C are negligible for most applications.

Illumination of the sample with a high NA cone implies that incident rays, carrying the length of the ruler (the wavelength), are not all parallel to the optical axis. As a consequence an empirical correction factor has to be applied to height measurement [Mykura 1963, Creath 1989, Schultz 1991]. Such correction factor is not needed with DHM®.

James Clerk Maxwell (1831–1879) has been one of the first to suggest using the wavelength as a natural gauge for length. In 1950, the standard meter in the new International System of Units (SI) is referred to the wavelength corresponding to the krypton-86 (605,780 nm).  The use of a precise wavelength as a reference for the measurement of  lengths is well established as the ideal measurement method.

Laser metrologyequipment

As a rule, frosted glass is not suitable for recycling through glass bins.[1] This is because the etchants used to produce some frosted glass can leave chemical residue, which can interfere with the recycling process and spoil a whole batch. Frosted glass that was not acid-etched but rather produced by sandblasting is recyclable in principle, however, since it can be hard to tell how a given piece of frosted glass was manufactured, most recyclers will reject frosted glass absent a contract with specific assurances.

Measurement of standardized samples, as well as direct comparison of measurement performed with other metrological tools have demonstrated the high accuracy and repeatability of DHM® [Colomb 2010].

In the 21st century, DHM® by Lyncée Tec refer to wavelengths for height measurements. By using ultrastable interferometric filters for selecting a precise wavelength band of a relatively broad spectrum laser source, DHM® operating wavelengths are precisely controlled and perfectly stable. The height values do not depend on any calibration,  precise positioning, or repeatability of interferometric piezo-controller, neither on any motorized displacement, or confocal detection system. DHM® provides thus precise measurements with very high repeatability.

Laser metrologycourse

Frosted glass is produced by the sandblasting or acid etching of clear sheet glass. This creates a pitted surface on one side of the glass pane and has the effect of rendering the glass translucent by scattering the light which passes through, thus blurring images while still transmitting light. It has 10–20% opacity.[citation needed]

The frosted glass effect can also be achieved by the application of vinyl film, used as a sort of stencil on the glass surface. "Photo-resist", or photo-resistant film is also available, which can be produced to mask off the area surrounding a decorative design, or logo on the glass surface. A similar effect may also be accomplished with the use of canned frosted glass sprays.

Lyncée Tec provides optionally a certificate issued by the Swiss National Metrology Center METAS for the transmission spectrum of the interferometric filter used to control the central wavelength and spectrum width. The operating wavelengths of the DHM® and thus heights measurements are fully controlled since no other critical distance or displacement are involved in the height measurement.