The interference pattern of the optical path difference between an aspherical optical surface and the corresponding best fit spherical surface is the Aspherics Characteristic Interferogram (ACI), which can be used as a template to test aspheric optical surfaces without test plates or null compensation systems. This direct interferometry can be used in the optical shop testing & in the digital phase-shifting spherical Fizeau interferometer to achieve high precise aspheric surface testing automatically. We succeeded in testing several aspheric surfaces by this method. AC! is also the base of phasing segmented mirrors, and six small-segmented mirrors were successfully combinated to a large mirror. If used in the infrared red interferometer, strongly aspheric surfaces with asphericity more than 4Oim can also be tested. Experiments show that the ACT is a fast, effective aspherical surface measurement technique.
For fabricating a high gradient aspherics, we have designed a ZDCCOS complex, which consist of a CNC Polisher and a CQG1J digital wavefront interferometer. The Polisher has S degrees of freedom. The computer makes a small tool to move in three dimensions and drive the workpiece to sway, and turn around simultaneously to keep the pad in the normal directions of the workpiece surface. We designed a special dual-rotation tool and presented a new model to calculate the removal function of which. The model was verified by the experiments. The track programming algorithm was also designed to make the tools to move on spatial concentric circles, during the fabrication processes. The work piece was a 3OO mm, F5.9 focus lens, the aspheric degree of which was up to 46 rim. But only after 8 hours 43 minutes continuous fine grinding, and about 15 hours polishing, the surface error was decreased to I . (Rms. X=0.6328 rim).
This paper discussed some non-contact measuring methods of optical surface roughness. Three types of opt:ical interference proflIorneters researched ir China is mentioned. Some unique techniques used in them is introduced. The advantages and disadvantages of them for on-line measuring are discussed. L]NTRODUCTTONAs the requirements of high-precise optical surfaces are increasing rapid'y, the need for on-line surface roughness measureme:nt arises. An on-line profilometer can measure the product's surface immediately after a polishing process w:ithout unloading the product. The profile measured can direct next polishing process or tell when the product is acceptable and needn't further polishing.an an--line profilometer car minimize the polishing time, and so reduces the costs.Stylus profiometer is common used in measuring laboratorIes. One problem of this kind of profilometer is that the stylus contacts at the surface at extremely high pressure, that may damages the surface or the stylus itself. This problem is even severer when for on-line detecting, because that the mechanical vibration will bring a bad effect. Another problem is that the speed of measuring is too slow. So a non--contact measuring method is preferable than a contact one for on-line detecting.r1lLere are many kinds of non--contact measuring methods, but not all of them is available for on-line detecting. The most concerned problems for a on-line profilometer include: 1. The profilometer is sensitive to height variation of O,lnm level, which is the level of a precise optical surface's surface roughness; 2, The profilomete:r must be 100/SPIE Vol. 1720 (1992) 0-81 94-0887-5/92/$4.00 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/27/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx
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