A fiber optic sensor for measuring the diameter and from errors of very small hole or blind hoe. with diameter down to 0.2 mm and depth to diameter ratio up to 20 was developed. Since optical non-contact methods are difficult to use for measuring the diameter and from errors of small hole at any cross section, a fiber optic sensor, which combines the advantages of optical non-contact method and mechanical contact one, was proposed. The principle is based on the evaluation of a central position of stylus ball by an optical system. Experiments show that the accuracy of the system is better than 1 micrometers and the measuring force is less than 10 (mu) N.
An opto-mechanical microprobe system which combines the advantages of optical non-contact method and mechanical contact one is proposed for measuring very small parts on coordinate measuring machines. The principle is based on the evaluation of a central position of stylus ball by an optical system, the stylus ball is illuminated by a cold light source through an optical fiber. The most inventive advantage of the microprobe is that the deformation of its stylus does not influence the measuring results, so the stylus could be extremely thin. Until now an opto-mechanical microprobe with stylus ball of diameter of about 40 micrometers and stylus of diameter of about 20 micrometers is developed. Experiments show that the accuracy of the opto-mechanical microprobe is better than 1 micrometers and the measuring force is less than 10 (mu) N.
In this paper, a differential constant angle interferomethc system for measuring arbitrary angles, based
on the principle of the differential constant angle interferometer in combination with the laser
interferometer for measuring small angles, is proposed. The system comprises a two-stage precise rotary
table, an optical polygon, two differential constant angle interferometers, a laser interferometer for
measuring small angles and a data processing system for interferometric fringes. In accordance with the
characteristics of the differential constant angle interferometric system for measuring arbitrary angles,
a theory of self-calibration is proposed including determining the equivalent parameters of the laser
interferometer for measuring small angles, calibrating the optical polygon by using the method of the
correlative differential constant angle and so on. High accuracy, self-calibration ability and new
measuring principles, are the distinguished features of the differential constant angle interferometric
system for measuring arbitrary angles. A series of experiments show that the differential constant angle
interferometric system for measuring arbitrary angles gives an accuracy better than 0.3" in measuring
arbitrary angles ranging from deg; to 360°.
In this paper a laser interferoeter for measuring small angles with an accuracy better than 0. 01 arcsecond is proposed. 1 THEORY The diagram of the interferometer is shown in Fig. 1. When the angle 1--laser 2--beam-expanding lens 3--pin--hole filter 4--collimating lens 5--aperture 6-- beam-splitter 7-CCD component 8--detector for stabilizing laser Mirrors A B--measuring reflectors Mreference mirror composed by mirrors A B is equal to X/(2m1) m1 . . the mirrorimages of Fig. 1 mirrors A B are in the same plane equal spacings on both sides of the visual field will be formed. When A rotates about 0 a small angle 4 the mirrorimages A B are not same plane and fringe spacings on two sides of the visual field be unequal. Plus sign is taken when mirror A rotates clockwisely sign for counterclockwise rotation. We have 4A(1/e 1/ca )/(4m2) (1) where e e1 are shown in Fig. 1. In order to get adequate interferometric field keep fringe straight enhance the contrast of the fringe and keep the contrast constant the lengths of mirrors A B should be long enough R:T ratio of splitter should be determined according to how many times the incident beam being reflected between mirrors A B and the reflective index of mirrors A B and the interferometer should satisfy the equivalent sine condition/''- Definite Fourie Transfer mode of processing interferometric fringe is adopted in this
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