From 4D Technology Corporation

Interferometry is used for testing optical components and optical systems as well as the metrology of many other components, such as the flatness and roughness of hard disk drive platters and the shape of magnetic recording heads and machined parts.

This article describes three recent advances that are broadening the applications of interferometric metrology: a new technique for reducing the sensitivity of interferometry to vibration; an interferometric method for measuring deformations and vibrations of diffuse surfaces; and a method for reducing the sensitivity to vibration and coherent noise and enabling measurement of parallel glass surfaces.

Before delving into these new techniques, I will first describe phase-shifting interferometry, which is critical to all three advances. Moreover, the phase shifting technique has greatly increased the popularity and the usefulness of interferometry in industrial and research applications.

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Product Announcements
Bruker Nano Surfaces Division - Bench Top 3D Surface Metrology
The ContourGT-K0 3D Optical Microscope utilizes white light interferometry to measure surface topography from nanometer-scale roughness through millimeter-scale steps, with sub-nanometer resolution,... (read more)
Knight Optical Ltd. - High Quality Quartz Optical Flats
Knight Optical offer a range of optical flats in Zerodur® and Quartz for interferomettery reference and mirror substrates. (read more)
Bruker Nano Surfaces Division - Surface Characterization Of Dynamic MEMS
Utilizing the latest advances in white light interferometry technology, the ContourGT InMotion™ 3D Optical Microscope performs three-dimensional surface measurements of features from 0.1nm to... (read more)
M+P Labs - Surface Prep, Coating and Plating Evaluations
M+P Labs applies a wide range of analytical techniques to evaluate surface preparation and characterize coatings and platings. Features such as chemical composition, cleanliness, surface topography,... (read more)
Lapmaster International - Interferometer Flatness Measuring
The Lapmaster/LAMTech TOPOS and SPI series of Interferometers feature Grazing Incidence flatness inspection and measurement capability for ground, lapped & polished surfaces. Use of this system... (read more)
Bruker Nano Surfaces Division - Metrology for Process Quality Control
The Contour GT-X 3D Optical Microscope family provides the highest performing, non-contact surface measurements for laboratory research and production process control. The pinnacle of ten generations... (read more)
Norland Products, Inc. - Automated Non-Contact Interferometer, Fiber Optics
The Norland Advantage Multifiber System is an automated non-contact interferometer designed for measuring the end face geometry of fiber optic connector surfaces including multifiber connectors, fiber... (read more)
 

Topics of Interest

In the testing of optical components and optical systems there are many requirements on the precision and accuracy, measurement time, ease of use, dynamic range, and environmental conditions.

3.4 Phase modulating sensors and interferometric techniques Optical interferometry is a well established technique which is associated with high resolution optical spectrometry and the precise...

There are three types of optical strain gauges: photoelastic, Moire interferometry, and holographic interferometry. Photoelastic strain gauges subject an elastomeric material to a load and illuminate...

The technique for measuring changes in diffuse surfaces using Electronic Speckle Pattern Interferometry (ESPI) is well known. We present a new electronic speckle pattern interferometer that takes...

Mechanical vibration and turbulent airflow present significant problems for most interferometric test methods. Conditions on the factory floor and in industrial clean rooms with high-capacity air...