Cat's Eye Resonator HeNe Laser And Its Displacement Sensors

The resonating stability of a laser is always an important research project for laser performance,and the conventional resonator is very sensitive to the swing of its cavity mirrors. This thesis researches the stability of HeNe lasers by employing the cat's eye resonator, and introduces two novel displacement sensors based on the cat's eye resonator HeNe laser.Experiment results in this thesis prove that: in the half-external and full-external cavity HeNe lasers, cat's eye cavity can improve laser stability greatly, enhance the maximum misalignment angles of the reflecting mirror up to 10 and 60 times respectively, and lower the power drifts significantly. If the convex lens center of cat's eye reflector is ensured in the laser bore axis, the adjustment-free performance of the cavity can be realized, founded on which the half-external and full-external cavity adjustment-free HeNe lasers are developed successfully. When the distance between the convex lens and concave mirror is regulated, the laser beam pattern will be modulated, according to which the transverse mode patterns can be selected to assure the fundamental transverse mode operating.Theoretic analysis is carried out comprehensively for the cat's eye resonator HeNe laser, including analyzing the Gauss beam character in the equivalent confocal resonator method; studying the misalignment character respectively in geometric method and matrix optics with misalignment sensitivity parameter; calculating the influences to the resonator introduced by the dimensional and abaxial errors; discussing the case in which a wedge-shaped element is inserted into the laser cavity; researching the transverse mode selection phenomena by solving the two-dimensional diffraction integral equation with Newton-Cotes method. The analysis results match the experiments very well.The"Displacement self-sensing laser system"is a successful exemplification applying the cat's eye resonator HeNe laser into the displacement measuring field. Much significant improvement is carried out to solve its long-term stability problem, and make it a mature apparatus used in industry and metrology realm. Accordingly its application area is widened to be competent for measuring the gage block thickness and calibrating the linearity and accuracy of the inductance displacement sensor.An original"cat's eye folded resonator"is built, based on which another new displacement sensor named"folded resonator--displacement self-sensing laser system"is set up, and its principle, two kinds of structures and fabrication procedure are presented detailedly. Both the theoretic analysis and comprehensive experiments show that the folded cat's eye resonator has higher stability than the common one. Practical displacement measurements are made, ideal and stable power tuning curves of the two orthogonal polarization lights obtained. Calibration by HP 5529A laser interferometer indicates that the sensor has a high resolution of 39.55nm, a large measurement range up to 14.4mm, and a tiny linearity error of 4.2×10-5. Measurement error is analyzed and the design project of the new circuit is discussed.