This section provides an overview for interferometers as well as their applications and principles. Also, please take a look at the list of 16 interferometer manufacturers and their company rankings.
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An interferometer is a device that measures the interference phenomenon that occurs when light shines on an object.
The interference phenomenon differs depending on the object's material, surface condition, and other factors. Based on the differences in interference phenomena, it is possible to measure the surface shape, refractive index, object size, etc., of each object.
The size that can be measured by the interferometer is a few to several dozen centimeters at most. If the sample to be measured is large, it must be cut into pieces.
Interferometers include Michelson interferometers, Mach-Zehnder interferometers, and Fizeau interferometers. Among these, the Fizeau interferometer is the most common.
Interferometers can measure multiple elements, but are most often used to measure refractive indices.
Specifically, it is used to evaluate the performance of anti-reflective films for glass and base films.
When light strikes glass or base film, reflections occur. When reflection occurs, transmission quality deteriorates due to noise generation and loss of transmitted signals. Therefore, it becomes necessary to suppress reflection.
The light reflected by an antireflection film is designed to be in the opposite phase of the light reflected on the surface of the base material. Light with different phases causes interference phenomena and cancels out each other's light. Cancellation allows all light to pass through.
In addition to visible light, anti-reflective filters are also made for ultraviolet and infrared light.
Interferometers use the phenomenon of interference to make measurements.
Light has the properties of a wave. Due to its wave nature, it oscillates periodically. When different waves overlap, the state of vibration changes and a new wave is generated. The generation of new waves by superposition is called interference. Depending on the type of overlapping wave, not only does it take on a new shape, but the wave itself may also disappear.
Since waves are periodic, they are commonly represented by sin and cos functions.
In addition to wave properties, light also has particle properties. The intensity of light varies depending on the number of particles. If the number of particles is large, the light becomes stronger; conversely, if the number is small, the light becomes weaker. The shape of the wave changes according to the intensity of the light; if the light is weak, the wave becomes wider.
When the surface is roughened, light enters at an angle, so the light hitting the surface is weaker than when the light enters straight on. This can be used to determine the surface condition.
Numerical analysis is performed using the obtained interference fringes. One typical method is the Fourier transform.
By performing the Fourier transform, the frequency spectrum is extracted from the interference fringes. The inverse Fourier transform of the extracted spectrum yields the phase information of the measured material.
Radio interferometers are known as a type of radio telescope.
It is an observation device in which multiple radio telescopes are placed at a distance from each other, and the received radio waves are interfered with to obtain an effectively high resolution. It is characterized by resolution equivalent to that of a giant radio telescope, which is not possible with a single radio telescope.
Interferometers use a process that interferes with electromagnetic waves of specific frequencies (wavelengths) obtained from a pair of telescopes to find the conditions under which they are most likely to enhance each other.
When the signals from the two telescopes are adjusted to be most intensified, the optical path difference between the two telescopes at that time is accurately measured. The principle of this method is that the measured optical path difference can be used to determine the exact position of a celestial object.
One of the most famous radio telescopes using this principle is the ALMA telescope.
The ALMA telescope was built in the Atacama Desert in the Republic of Chile, South America.
The ALMA telescope consists of numerous small telescopes arranged in a large area that work together to form a single giant radio telescope. This is a giant radio telescope.
One reported application of interferometry is the measurement of gravitational waves using a laser interferometer.
In this gravitational wave measurement, a Fabry-Perot resonator is constructed with two mirrors, into which light from a laser is incident.
Reflected waves in two directions that are reflected back from the mirrors of the resonator interfere with each other, strengthening and weakening the light.
When the peaks and troughs of the two reflected waves are adjusted so that they overlap, they weaken each other and cancel each other out.
In this situation, when a gravity wave arrives, one of the two directions of space stretching in a perpendicular direction is extended and the other is contracted.
The distance traveled by the laser beams in the two directions changes slightly, causing a slight shift in the overlap of the peaks and troughs of the intersecting laser beams.
By observing the interference light signal detected the gravitational wave signal can be detected.
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Ranking as of June 2023 GloballyDerivation Method
|2||MÖLLER-WEDEL OPTICAL GmbH||7.7%|
|5||RP Photonics AG||7.7%|
|6||4D Technology Corp||7.7%|
|8||PI (Physik Instrumente) L.P.||7.7%|
|12||Motion X Corporation||7.7%|
Derivation MethodThe ranking is calculated based on the click share within the interferometer page as of June 2023. Click share is defined as the total number of clicks for all companies during the period divided by the number of clicks for each company.
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