Techniques Of Testing Aspheric Surface Of High Accuracy With Compensation

Compensation null test is a important method in testing aspheric surfacewith high accuracy. In this thesis, some key techniques of compensationmethod for testing aspheric surface are studied.First we take the mold corn of DVD optical pick-up objective lenses asan example, a design is presented for an objective lenses witch is related tothe testing, a kind of structure of compensator for testing small asphericsurfaces with large NA is put forward, and a compensator for the beingtested mold corn aspheric surfaces is designed, the analyses to thiscompensator shows we are capable of measuring the aspheric surfaces moldcorn to the accuracy(RMS) of 0.05λRMS, it is enough to satisfy thetesting of mold cone surface.Second, lenses compensator with high accuracy has great quality requestto the homogeneity of optical glass. In this thesis, a high accuracy apparatusfor testing the homogeneity of optical glass is developed, and the test resultshows the measurement error is less than 1×10^-6. To different condition,two new absolute homogeneity testing methods is put forward.Third, to get ideal lens compensator, sometimes we had to use surfaceswith long radius of curvature. For testing this kind of surfaces with longradius of curvatures, a high accuracy method is put forward. In the method,another compensator, which is made of two different glasses with very smalldifferential of refraction index, is used to generate long focal leneth. Theanalyses to this kind of comnensator for a convex mirror of radius22000mm and a concave mirxor of radius 5600mm show the accuracy totest radius is capable of 0.1% and the accuracy to surface errors(RMS) iscapable ofλ/150.