Absolute measurement of gauge block without wringing using tandem low-coherence interferometry

Abstract

A novel method of gauge block measurement without wringing onto a glass platen is proposed. By using tandem low-coherence interferometry to perform remote measurements, wringing is rendered unnecessary. To measure its length, a gauge block for measurement without wringing is set several millimeters above a glass platen that is positioned on a triangle interferometer such that the distances between the surfaces of the block and the reflection surface of the platen can be measured from opposite directions. By using tandem low-coherence interferometry with a He–Ne laser as a reference length standard, gauge blocks with nominal lengths of 5, 10 and 75 mm have been measured remotely with an expanded uncertainty of about 86 nm.

A review of interferometry for geometric measurement

“…Taking a He-Ne laser interferometer as a reference length standard, an internal distance of up to 100 mm was measured with an uncertainty of 178 nm. This is also available for gauge block interferometry [143].…”

Noncontact method of point-to-point absolute distance measurement using tandem low-coherence interferometry

“…To precisely measure the optical path lengths L OPL1 and L OPL2 , we considered several noncontact length measuring methods for our system [12][13][14][15][16][17][18] and chose the tandem lowcoherence interferometric method because it can determine positioning at 10-30 nm level [12,13]. To perform tandem low-coherence interferometry, reference and measurement interferometers were connected by a single-mode optical fiber.…”

“…Therefore, the reference interferometer, which functions as an optical path compensation interferometer, was set up to generate low-coherence interference fringes. The reference and measurement interferometers can be separated in the range from several metres up to several kilometres [12,13,19], thus allowing remote measurement by the tandem low-coherence interferometer.…”

“…Furthermore, they use He-Ne laser interferometer, which cannot perform absolute distance measurement, for measuring displacement [6,8]. The absolute distance measurement by using the tandem low-coherence interferometric method provides the possibility to perform remote measurement of the internal distance between two points [12,13]. Hence, we propose a new method for directly measuring the absolute internal distance between two points without the use of angle or coordinate information by using a tandem low-coherence interferometer.…”

Length Traceability Using Interferometry

“…Abdelaty [29] has shown for a similar set-up that there are challenges, especially as the phase correction has to be applied twice and its uncertainty contributes accordingly, and additional mirrors and beam splitters of high quality are needed. Another approach was taken by Winarno et al [30], who combine a double-sided interferometer in a triangle configuration with a displacement measurement that can be carried out remotely. In this case, the uncertainty of traditional gauge block interferometry has not yet been achieved.…”