Optical Measurements Using Bessel Beams

Abstract

The characterization of optical beams generally involves interferometric instrumentation where, most often, a reference arm must be stabilized to a fraction of a wavelength. The classical methods of interferometry are well suited for the testing of optical components in clean, vibration-free laboratories. However it happens frequently that optical beams are used for sensing surface deformations in various industries; it turns out that, in most industrial environments, conditions are adverse to interferometric measurements. In this paper we describe an optical technique that provides a direct reading of the curvature of an optical wavefront without the requirement of interferometric stabilility. The physical principle behind the technique is the phase sensitivity of the interference pattern produced by copropagating Bessel beams. The technique is robust against vibrations since it does not involve any reference arm; however it yields global information about optical beams, and not pointlike information as do most interferometric instruments. The technique is also appropriate to the measurement of the nonlinear properties of optical materials. We recall that, in recent years, the optical characterization of various types of nonlinear materials has become a subject of growing importance due to the needs of photonic technology.