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In order to solve the difficulties in testing surface of long focal length mirror using interferometer,a novel optical metrology using phase retrieval is developed.In this method,tested mirrors is illuminated by a coherent point light source,a series of diffraction intensity patterns near focus are collected,then phase retrieval algorithm reconstructs the surface error of tested mirror.Compared with interferometer,it simplifies the metrology setup and requires no special environment.Mathematic model of phase retrieval measurement is found according to diffraction theory,and is solved by iterative algorithm which derives from Gerchberg-Saxton algorithm.Validity of this method is tested by simulations and an experiment.A spherical mirror with curvature radius of 8 700 mm and diameter of 145 mm is tested using phase retrieval.The position of intensity patterns are corrected and appropriate patterns are chosen to be computed.The reconstructed result is correlated well with that tested by simultaneous phase-measurement interferometer.

The formulas for atomic displacements and Hamiltonian of a thin crystal film in phonon occupation number representation are obtained with the aid of Green's function theory. On the basis of these results, the formulas for thermal expansion coefficients of the thin crystal film are derived with the perturbation theory, and the numerical calculations are carried out. The results show that the thinner films have larger thermal expansion coefficients.

In order to simplify sidewall electrode pattern of quartz gyroscope, a novel micro-structure used to sense Coriolis’ force based on shear stress detection is demonstrated. The approach of shear stress detection is analyzed and the structure of sidewall electrode is a single polarity electrode. A tapered beam with 15° taper designed as the sensing beam can increase its sensitivity. A prototype structure is fabricated by processing z-cut quartz by anisotropic wet etching technique. The prototype has a drive mode frequency of about 5.6 kHz, and the quality factor is over 5000 in atmosphere. The spectrum analysis of the structure’s output signal reveals the Coriolis force, which validates our new design scheme.

This paper presents a novel structure for improving the stability and the mechanical noise of micromachined gyroscopes. Only one slanted cantilever is used for suspension in this gyroscope, so the asymmetry spring and the thermal stress, which most micromachined gyroscopes suffer from, are reduced. In order to reduce the mechanical noise, the proof masses are designed to be much larger than in most micromachined gyroscopes. The gyroscope chip is sealed at 0.001 Pa vacuum. A gyroscope sample and its read-out circuit are fabricated. The scale factor of this gyroscope is measured as 57.6 mV/(deg/sec) with a nonlinearity better than 0.12% in a measurement range of ±100 deg/sec. The short-term bias stability in 20 min is 60 deg/h.