Polygon scanners for laser scanning have reached incredibly high rotation rates: the common high-end rate now is 55,000 revolutions per minute (RPM), which, for a 2.5-in.diameter, 72-facet scanner is a mirror-facet speed of 660 km/h. The speed of sound at sea level is 1,236 km/h, so the mirror-facet tips are traveling at more than half the speed of sound. The result is a device that sounds like a siren, according to Precision Laser Scanning (Scottsdale, AZ) — fine for industrial environments, but not acceptable, for example, in a biomedical lab.
Up to 70,000 RPM
Precision Laser Scanning has just unveiled an even higher-speed polygon scanner that rotates at up to 70,000 RPM — a mirror-facet speed of 840 km/h, or two-thirds the speed of sound. However, the scanner is housed in a sealed container with an optical window, which makes it, according to the company, "whisper-quiet." Because the enclosed mirror housing does trap heat that is normally removed by the free flow of air over an open polygon, the mirror housing has cooling fins for heat transfer and a small fan must be used to move air through the fins.
Biomedical, inspection, and display applications should benefit.
