1. An optical device consisting of two parallel, partially reflective surfaces that create interference patterns, used in spectroscopy and laser technology to measure wavelengths and filter light.
Usage: technical; physics

Examples

• The physicist used an etalon to measure the precise wavelength of the laser light.
• An etalon's high resolution makes it valuable for spectroscopic analysis.
• The etalon consists of two glass plates with reflective coatings on their inner surfaces.
• Researchers calibrated the etalon to detect minute shifts in light frequency.
• Modern telecommunications systems often employ etalons for wavelength filtering.