Terahertz Displacement and Thickness Sensor with Micrometer Resolution and Centimeter Dynamic Range

Area of Science:

• Physics
• Materials Science
• Optical Engineering

Background:

• Simultaneous measurement of distance and thickness is crucial across diverse scientific and industrial fields.
• Existing methods may lack the precision or range required for certain applications.

Purpose of the Study:

• To develop and validate a novel technique for simultaneous displacement and thickness measurement of transparent materials.
• To utilize pulsed terahertz waves for high-resolution, centimeter-range metrology.

Main Methods:

• A pulsed terahertz wave system was designed with a beam splitter for vertical incidence.
• The optical path was optimized for centimeter measurement range and micrometer resolution.
• Thickness was determined from the time difference between terahertz wave reflections from the sample's surfaces; displacement was measured by tracking positional changes.

Main Results:

• The technique demonstrated a measurement range of 1 cm with displacement errors under 23 μm.
• Thickness measurements exhibited an error of less than 8 μm.
• Experimental validation was performed using aluminum, acrylic, and glass plates.

Conclusions:

• The proposed pulsed terahertz wave method offers a viable solution for simultaneous, high-accuracy measurement of displacement and thickness.
• This technique holds potential for applications in biological, medical, and electronic industries requiring precise material characterization.