Conical beam-based laser profilometer for testing roller bearings

Abstract

In the last years the investigations in the area of optics of Bessel and their associated conical beams are being shifted from the domain of scientific research to the one of practical applications. This is appreciably due to new potentialities of the practical use of these light fields, which are not realizable in the framework of traditional optics of Gaussian beams. The spatio-angular properties of conical light beams are optimal to control the form and quality of surfaces close to cylindrical and conical ones. This is related to the fact that a conical light beam enables one to realize the longitudinally uniform illumination at a certain angle. The grazing-incidence geometry of illumination permits one to significantly reduce the speckle noise in the field reflected and to extract, thereby, information on the macroscopic shape of the surfaces. In this work we develop two optical profilometers intended for non-destructive testing of objects having the form close to the cylindrical one. In particular, a new scheme of vibration-proof laser profilometer based on using the superposition of two conical beams is proposed. A laboratory optical setup of the profilometer is designed. The developed device includes two ring diaphragm as a basic element for crating two conical light beams. One of these beams serves as a reference beam and the second - as an object one. As a result, the independent reference arm has been removed and a single-arm scheme has been realized. The conical beams are spatially separated so that one beam illuminates the cylindrical surface and another beam is freely propagates. Due to a single-arm configuration, this profilometer is noted for a high mechanical stability. The experimental testing of the laboratory setup has confirmed this property of the device. The methods of eliminating the systematic errors and the misalignment aberrations are developed. The conical beam - based profilometer applies to controlling various cylindrical and conical samples including the roller bearings. It is shown that the single-arm profilometer is suitable for testing the roller bearings, because it is vibration-proof and also provides an enough measuring accuracy. Besides, this type of profilometers is not time consuming, which allows the online control of bearings.