Microinterferometer

microinterferometer

[¦mī·krō‚int·ə·fə′räm·əd·ər]
(optics)
Functional combination of a microscope with an interferometer; used to study thin films, platings, or transparent coatings.

Microinterferometer

 

an instrument used to measure unevenness of external surfaces that have directional machining marks, and also to determine the thickness of films and the magnitude of small displacements. The first microinterferometers were developed by V. P. Linnik in 1933.

The optical scheme of a microinterferometer includes an interferometer and a microscope, which make possible simultaneous observation of the surface being studied and the interference pattern produced by two coherent light waves (a reference wave, which is reflected from a reference mirror, and a wave that is reflected from the surface being studied and is distorted by its microscopic unevenness). For monochromatic light the interference pattern consists of alternate dark and bright fringes, the shape of which reproduces a magnified profile of the portion of the surface being inspected. The height h of a surface unevenness is determined from the warping a and width b of the interference fringe: h = a/b . λ/2, where A is the average wavelength of the region of the spectrum used. Heights of 0.03 to 1 micron (JLL) can be measured.

Microinterferometers are manufactured for operation in white and monochromatic light. They are equipped with an eyepiece micrometer for making measurements or with an eyepiece and camera to record the interference pattern. Some microinterferometers have devices for measuring unevennesses up to 10 ju from impressions of the surfaces being studied.

REFERENCES

Egorov, V. A. Opticheskie i shchupovye pribory dlia izmereniia sherokhovatosti poverkhnosti, 2nd ed. Moscow, 1965.

L. N. LOGACHEVA

References in periodicals archive ?
The main part of the automated variable wavelength interference microscope [34] is the Biolar PI microinterferometer that is fitted with a Halogen lamp (12 V,100 watt) as a source white light, wedge interference filter to provide highly monochromatic light, stepper motor controller, CCD camera, and image display monitor.
The automatic microinterferometer is adjusted in the two positions.
The annealed PP samples were placed on the microscope stage and the microinterferometer was adjusted in subtractive and crossed positions for measuring the birefringence and the refractive indices of the fiber, respectively.
The surface roughness was measured with a phase-measuring microinterferometer. The average roughness, [R.sub.a], ranged from 10 nm to 15 nm at different locations on the flat surfaces of K79 with repeatability of 1 nm for a single measurement location.