title: High resolution heterodyne interferometer without detectable periodic nonlinearity.
abstract: A high resolution heterodyne laser interferometer without periodic nonlinearity for linear displacement measurements is described. It uses two spatially separated beams with an offset frequency and an interferometer configuration which has no mixed states to prevent polarization mixing. In this research, a simple interferometer configuration for both retroreflector and plane mirror targets which are both applicable to industrial applications was developed. Experimental results show there is no detectable periodic nonlinearity for both of the retro-reflector interferometer and plane mirror interferometer to the noise level of 20 pm. Additionally, the optical configuration has the benefit of doubling the measurement resolution when compared to its respective traditional counterparts. Because of non-symmetry in the plane mirror interferometer, a differential plane mirror interferometer to reduce the thermal error is also discussed.
authors.affiliation: Mechatronic System Design, Department of Precision and Microsystems Engineering, Delft University of Technology, Delft, The Netherlands. k.joo@tudelft.nl
authors.forename: Ki-Nam
authors.initials: KN
authors.lastname: Joo
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Ellis
authors.forename: Eric S
authors.initials: ES
authors.lastname: Buice
authors.forename: Jo W
authors.initials: JW
authors.lastname: Spronck
authors.forename: Robert H Munnig
authors.initials: RH
authors.lastname: Schmidt
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D007368:Interferometry / Q000295:instrumentation*; D007834:Lasers; D007909:Lenses; D017711:Nonlinear Dynamics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity