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Thickness Measurement Technology

How It Works

Utilizing the unique properties of light, the Optical Thickness Gauge (OTG) accurately measures the thickness of transparent and semi-transparent materials. To make a measurement, light is transmitted into the material resulting in reflections at each surface and layer interface which can then be collected and analyzed by optical interferometry. Our unique interferometer design provides an “optical ruler” that very precisely measures the difference in length traveled by each reflection to determine total thickness and the thickness of each layer.

Because this optical technique is so effective, the Optical Thickness Gauge can collect and analyze the reflections from a sample as thin as 12 μm or as thick as 80 mm and simultaneously measure as many as 31 layers.

The Measurement Process

(1) The Optical Thickness Gauge System includes a super-luminescent LED (SLED), interferometer assembly, and a digital signal processor (DSP) housed within a rugged rack mountable chassis.

(2) Light from the SLED is sent to the material under test through an optical probe that is connected to the OTG system by a flexible fiber-optic patch cord.

(3) Reflections from the material under test are collected by the optical probe and returned to the OTG system's interferometer for analysis.

(4) Thickness data is calculated using the onboard processor and then transferred via USB or Ethernet to connected PC.


(5) The Windows-based Opti-Cal™ software is used to control measurement parameters and report thickness data in a variety of formats.

Continuous Calibration

Our Thickness Gauges includes a built-in HeNe laser as an invariant standard of length. Every measurement is compared to this standard, guaranteeing the accuracy of your results.

Are you looking for fast, accurate thickness measurements of your transparent or semi-transparent material? Contact us to schedule a demonstration and learn more about our thickness measurement technology.