Interferometry is a measurement technique used to study waves, particularly electromagnetic waves such as light. The basic principle of interferometry involves combining two or more waves that are out of phase with each other in such a way that they interfere constructively or destructively, resulting in patterns of light and dark areas called interference fringes.
In the context of light, interferometry is often used to achieve high-precision measurements of various properties such as distance, wavelength, phase, and even the shape of objects. It's employed in various fields for a wide range of applications such as astronomy, optical testing and metrology, particle physics, quantum mechanics, engineering and material science and medical Imaging.
The Michelson interferometer is one of the most well-known types of interferometers. It was used by Albert A. Michelson in the late 19th century to measure the speed of light and has since become a fundamental tool in various scientific and engineering disciplines.
Interferometry relies on the constructive and destructive interference of waves to extract precise information. It has significantly contributed to our understanding of wave phenomena and has led to many technological advancements.
Optics and photonics are crucial for interferometry, in order to manipulate and analyse light waves. Key optical components and principles used in interferometry include beam splitters, optical mirrors, collimators and lenses, polarizers and wave plates, detectors, interference filters, fibre optics and spatial light modulators (SLMs).
Optical products for interferometry on the market now
Vendors of interferometers and related optical equipment include Bruker, a manufacturer of high-performance scientific instruments and analytical and diagnostic solutions designed to enable scientists to explore materials at molecular, cellular and microscopic levels. The company provides interferometers and optical profiling systems for surface analysis and nanoscale metrology.
4D Technology designs and manufactures dynamic laser interferometers and optical profilers, and surface defect gauges. Applications include precision machined surfaces, optics, astronomy, aerospace, space-based telescopes, flexible electronics, automotive, and in-line production measurement.
DPSS lasers from Cobolt (part of Hubner Photonics) are all single longitudinal mode, with coherence lengths >10m, and so are a suitable choice of laser for interferometric applications. The company has a wide range of single frequency lasers for interferometric techniques, including holography, Doppler velocimetry and dynamic light scattering.
Horiba Scientific offers interferometric solutions for spectroscopy, ellipsometry, and surface characterisation in research and industry. The company’s Real Time Interferometric Process Monitor is designed to provide high-precision detection of film thickness and trench depth during the etching/deposition process. Depending on applications, the LEM camera includes a 670 or 905 or 980nm laser and when mounted on any dry etch/deposition process chamber with a direct top view of the wafer this generates a small laser spot on the sample surface.
The Profilm3D and Profilm3D-200 optical profilometers from KLA are designed to be affordable, non-contact, white light interferometry-based (WLI) 3D surface topography measurement systems. The latest generation includes imaging modes that extend performance and value. The Profilm3D series measures nanometer- to millimetre-scale surface with a simple, flexible recipe setup, accommodating single scans or automated measurements on multiple sites to support both R&D and production environments.
Keysight’s laser interferometer and laser calibration systems are designed to offer high precision in a wide dynamic range, alongside the ability to measure a position with multiple degrees of freedom, and high accuracy available in both air and vacuum systems.
The latest version of OSLO optical design software from Lambda Research has a default analysis that allows the user to compare each configuration with an absolute reference. This capability is sufficient for designing an interferometer. To model an interferometer in actual use, the user can then compare or "interfere" the wavefront of one configuration of the interferometer with the other.
Micro Laser Systems makes free-space and fibre-coupled lasers with diffraction limited performance. Lasers from 350 to 2000nm are available with accessories for expanding or focusing the beam, fibre collimators, fibre focusers, tiny collimators and splitters to integrate with the pigtailed lasers. Custom assemblies for OEM users are also available.
MKS Newport provides interferometers and associated products such as collimators, optical delay lines, fibre optic in-line polarisers, adjustable fibre optic collimators, open- and closed-loop nanofocusing objective lens mounts, sub-nanometer piezoelectric positioning resolutions, as well as fused silica interferometer flat optics.
Oxxius develops and manufactures diode pumped solid state (DPSS) lasers and laser diode modules in the ultraviolet, visible, and near-infrared wavelength ranges. The LCX series of DPSS lasers and the LBX series of laser diode modules have a compact design that can be easily integrated into various instruments for life science, measurement and manufacturing markets.
Teem Photonics develops and offers the PicoMove interferometers, compact, stable and high-performance interferometers for the measurement of picometer-scale displacements and vibrations. The interferometers are based on single-chip integration of a high-stability architecture which results in measurements with an intrinsic ultra-low noise. The eye-safe operating wavelength of 1.55µm provides compatibility with commercial telecom sources.
Thorlabs provides a wide range of optics and photonics products, including interferometers, optical components, detectors, and measurement systems.
Zygo Corporation specialises in the design and manufacture of advanced optical metrology instruments and systems, ultraprecise optical components and assemblies, and provides electro-optical design and manufacturing services.
This is not an exhaustive list. If you provide products in interferometry space and would like your company to be included, please let us know at: editor.electro@europascience.com
Hübner Photonics: Featured interferometry product
Hübner Photonics, manufacturer of high performance lasers for advanced imaging, detection and analysis, has one of the widest ranges of single frequency lasers in the industry for many interferometric techniques, including holography, Doppler velocimetry, laser ultrasonics and dynamic light scattering. All of the Cobolt 04-01 & 05-01 Series lasers, along with the C-WAVE Series of widely tunable lasers are single-frequency lasers with linewidths 10 m, and thereby very suitable for almost any interferometric-based application. The wide wavelength coverage of 355nm–1064nm (and even further in to the NIR), off ers full fl exibility to select the optimum wavelength for the specifi c interferometric-based technique. Manufacture using proprietary HTCure technology ensures a very high level of immunity to varying environmental conditions, ensuring the exceptional performance and reliability of all Hübner Photonics Cobolt lasers. Find out more about Hübner Photonics's lasers for interferometry at the company's website.
Knight Optical: Featured interferometry product
As a premier provider of high-precision optics, Knight Optical recognises the paramount significance of employing top-tier equipment to achieve optimum results. With its extensively equipped Metrology Laboratory, including a top-of-the-line ZYGO interferometer designed for measuring parameters such as flatness and form error, Knight Optical underscores the critical importance of utilising high-quality components in these systems. This commitment to excellence is reflected in its comprehensive lineup of optics tailored for interferometry applications, offering unwavering reliability and the highest calibre performance. Boasting an extensive selection of interferometry optics, Knight Optical’s portfolio encompasses:
- Beamsplitters
- Optical Flats
- Mirrors
- Lenses
- Waveplates
- Gratings
The optical specialist recognises that ready-made components may not consistently suit its customers’ needs. To address the demands of individuals engaged in specialised applications, Knight Optical provides custom-made options for its optical components, along with tailored optical coatings. Contact our UK and US teams and experience true precision, quality and innovation. Find out more about Knight Optical's range of solutions for for interferometry applications at the company's website.
Hamamatsu Photonics: Featured interferometry product
Interferometry in the palm of your hand: Hamamatsu Photonics’ MEMS-FTIR Engine is a technological innovation that integrates interferometry principles into a micro-electro-mechanical systems (MEMS)-based Fourier transform infrared spectroscopy (FTIR) solution. This cutting-edge engine combines the precision of interferometry with the miniaturisation capabilities of MEMS technology, resulting in a powerful, compact, and high-performance FTIR spectrometer. At the core of this technology is an interferometer that features a movable mirror whose position is precisely tracked by an integrated laser system to increase repeatability. This breakthrough allows for real-time, high-resolution spectral analysis in a handheld device. Researchers and industries can leverage the MEMS-FTIR Engine for applications such as chemical analysis, environmental monitoring, and process control. It outperforms bulkier bench-top instruments in terms of sensitivity and spectral resolution. The MEMS-FTIR Engine represents a pivotal advancement in interferometry technology, offering users the ability to perform intricate spectroscopic measurements with exceptional accuracy and portability. Find out more about Hamamatsu Photonics’ MEMS-FTIR Engine at the company's website.
