Design Of Heterodyne Interferometric Microscopy System For Metrology Of Free-form Surfaces

The design and fabrication of free-form surface optical elements have beenbeyond the traditional optical conception. Free-form surfaces have thecharacteristics of uncertainty, which provide modern optical design with many ways,so the designed optical system has the feature of higher image quality, simplestructure and small volume. These advantages make up for the defects of applyingthe aspherical optical elements in the aspect of engineering, especially in the field ofaviation and military where it has very special requirements for the quality andvolume of the load. Therefore, free-form optical elements have a wide range ofapplications. However, the uncertainties of free-form surfaces cause the difficultiesin fabrication and measurement. So it is necessary to do further research.The thesis presents a technique which combines heterodyne interferometrictechnology and confocal microscopy technology to measure the free-form surfaces.The optical system of heterodyne interferometric microscopy is designed for highaccuracy of measurement. Besides， this thesis has simulated and analyzedfree-form surfaces detection by means of confocal microscopy technology andheterodyne interferometric technology.According to the accuracy requirements of detection the surfaces, it makes surethe scheme of the measurement system, and explains the theory and characteristicsof infinite distance confocal imaging system in the consideration of ideal plane, aswell as the theory of measurement of phase of heterodyne interferometry technology.It makes sure the structure and parameters of confocal microscopy in order to finishthe design of structure. Secondly, the structural parameters of the laser beamexpander and collecting objective are finished. The first step beam expanded systemwith ratio of8.4and collecting objective system with the entrance pupil of8.4mmhave been finished. The concentrated energy of the laser beam expanded system isvery high, and the focused spot of collecting objective system is very small, whichmeets the design requirements. Finally, it applies confocal microscopy, collectingobjective and laser beam expanded system for the simulation of measurementsystem in the non-sequence space of the ZEMAX, where it can finish the simulationof confocal microscopy technology and heterodyne interferometric technology fortesting the measurement system.