High-Resolution Optical Thickness Measurement Based on Electro-Optic Dual-Optical Frequency Comb Sources Articles uri icon

publication date

  • March 2017

issue

  • 2

volume

  • 23

International Standard Serial Number (ISSN)

  • 1077-260X

Electronic International Standard Serial Number (EISSN)

  • 1558-4542

abstract

  • We propose an optical thickness measurement device based on electro-optic dual-optical frequency combs (dual-OFCs). Optical frequency combs (OFCs) are light sources that provide an optical signal consisting of many equidistant monochromatic tones. In this paper, we present an agile dual-OFC architecture with adjustable frequency separation of the comb modes and total frequency span, allowing high-resolution measurements of the thickness of transparent thick samples. This architecture is based on a single continuous-wave laser diode and external electro-optic devices to implement the dual-comb sensor, allowing easy control of the optical spectrum of the interrogation source (dual-OFC). As it is characteristic of dual-OFC systems, the optical transmittance function of the sample (etalon) is directly translated to the radiofrequency domain, where detection, demodulation, and processing of signals are performed. The shift in the complexity of implementation from the optical to the electronic domain yields many advantages, as acquisition and signal processing are made independently on the optical characteristics of the sample (thickness).

keywords

  • optical sensors; optical signal processing; optical reflection; frequency measurement; optical films; optical interferometry; optical variables measurement; dual-optical frequency comb (dual-OFC); fabry-perot etalon; optical interferometry; thickness measurement; thickness measurement; continuous wave lasers; etalons; fabry-perot interferometers; fiber optic sensors; interferometry; light sources; natural frequencies; optical materials; optical properties; thickness gages; fabry-perot etalons; high-resolution measurements; optical characteristics; optical frequency comb sources; optical frequency combs; optical interferometry; optical thickness measurements; transmittance function; signal processing