Optical metrology utilizes the properties of light, such as its wavelength, interference, and diffraction, to measure various physical quantities.

Interference, particularly constructive and destructive interference, is the key principle behind interferometric techniques used to measure distances with high precision.

Michelson interferometry involves splitting a light beam into two coherent beams, sending them along different paths, and then recombining them to observe the interference pattern.

Fizeau interferometry is commonly used to measure the flatness of optical surfaces, such as mirrors and lenses, by analyzing the interference pattern formed between the test surface and a reference surface.

Ellipsometry is an optical technique that measures the thickness of thin films by analyzing the change in polarization of light upon reflection from the film surface.

Diffractometry involves measuring the intensity distribution of light after passing through a grating or diffractive element to determine various properties, such as the grating period, wavelength of light, and material characteristics.

Optical profilometry is an optical technique that measures the surface roughness of a material by analyzing the reflected or scattered light from the surface.

Holography is an optical technique that allows the recording and reconstruction of 3D images of objects using coherent light.

Spectrometry is an optical technique that measures the wavelength of light by analyzing the dispersion of light through a prism or grating.

OCT involves measuring the time delay between reflected light pulses to obtain cross-sectional images of biological tissues or materials.

Refractometry is an optical technique that measures the refractive index of materials by analyzing the change in the direction of light upon passing through the material.

Optical tweezers use focused laser beams to trap and manipulate microscopic particles, enabling various measurements and studies in fields such as biology and physics.

Dynamic light scattering involves analyzing the time-dependent fluctuations in the intensity of scattered light to determine the size and shape of particles in a solution.

Photoacoustic microscopy uses pulsed laser light to generate acoustic waves in a sample, which are then detected to obtain images and information about the sample's structure and properties.

Ellipsometry can be used to measure the thickness of coatings by analyzing the change in polarization of light upon reflection from the coated surface.