A Novel Coordinate Measurement System Based on Frequency Scanning Interferometry

Abstract

Frequency scanning interferometry (FSI) is an absolute distance measurement technique that offers high accuracy, stability, and, potentially, direct traceability to the international system of units, the SI. In this article we present an overview of the basic principles of FSI, how we are adapting the technology used in conventional single-target FSI, and how we are combining it with the technique of multilateration to develop a flexible, high-accuracy, self-calibrating, six degreeof-freedom coordinate measurement system with inherent traceability to the meter. We present some initial results from a working prototype that currently operates over a spherical measurement volume of approximately 0.3 meters in diameter, discuss the issues associated with extending the working volume, and reveal how these are being addressed. machines (CMMs) or articulated arm CMMs; examples of the former include laser trackers and photogrammetric systems. Generally, for large-volume metrology applications, opticalbased technologies prevail because they tend to offer the benefits of longer ranges, portability, and versatility. Optical coordinate measurement systems can be further categorized as angle- or range-based. The former uses triangulation, for example, measuring angles from more than one location to a target to determine the coordinates of that target, such as with photogrammetry. A global position and navigation system (GPS) is an example of a range-based system. Laser trackers, laser scan