title: Absolute interferometry with a 670-nm external cavity diode laser.
abstract: In the past few years there has been much interest in use of tunable diode lasers for absolute interferometry. Here we report on use of an external cavity diode laser operating in the visible (lambda approximately 670 nm) for absolute distance measurements. Under laboratory conditions we achieve better than 1-microm standard uncertainty in distance measurements over a range of 5 m, but significantly larger uncertainties will probably be more typical of shop-floor measurements where conditions are far from ideal. We analyze the primary sources of uncertainty limiting the performance of wavelength-sweeping methods for absolute interferometry, and we discuss how errors can be minimized. Many errors are greatly magnified when the wavelength sweeping technique is used; sources of error that are normally relevant only at the nanometer level when standard interferometric techniques are used may be significant here for measurements at the micrometer level.
authors.affiliation: Engineering Metrology Group, Division of Precision Engineering, National Institute of Standards and Technology, Stop 8211, 100 Bureau Drive, Gaithersburg, Maryland 20899-8211, USA. jack.stone@nist.gov
authors.forename: J A
authors.initials: JA
authors.lastname: Stone
authors.forename: A
authors.initials: A
authors.lastname: Stejskal
authors.forename: L
authors.initials: L
authors.lastname: Howard