Introducing adaptive optics such as spatial light modulators (SLMs) can help troubleshoot the ‘one-to-one’ test mode of interferometric null surface figure tests for aspheric and free-form surfaces. However, the phase controlling accuracy of methods based on birefringence effects and phase-wrapping is too low for applying SLMs in interferometric surface figure tests. To this end, the flexible phase control method based on computer holography for SLMs is presented. The difference of phase control principle between the computer holography-based method and the birefringence effects and phase-wrapping based method is discussed. Phase control accuracy of the proposed method is about λ/30 (λ=632.8 nm) root-mean-square (RMS) according to the theoretical analysis result. The inherent wavefront error of a SLM HoloeyeTM LC 2012 is significantly nulled to from RMS 0.426λ to RMS 0.015λ, which verifies the high phase controlling accuracy of the proposed method. By troubleshooting the phase control accuracy issue, the presented method is promising for promoting the application of SLMs in interferometric surface figure tests.
Elastic emission polishing (EEM) has excellent polishing surface quality, and shear thickening can improve polishing removal efficiency. This paper mainly studies the effect of shear thickening slurry on EEM. Firstly, the polishing device and removal mechanism based on shear thickening are introduced. Then a single-point contrast polishing experiment was carried out. It is found that the shear thickening slurry can improve the removal efficiency of ordinary EEM, the former is about 2.7 times that of the latter.
Jet polishing plays an important role in ultra-precision machining. In this paper, the effects of slotted and slotless nozzles on micro jet machining are investigated. The pressure distribution and magnitude of the two nozzles on the workpiece were first calculated by finite element simulation software. Then a set of comparative tests were conducted on two single crystals of silicon. The results showed that the pressure distribution of the slotless nozzle was more uniform compared to the slotted nozzle, and the pressure value of the slotless nozzle on the surface of the workpiece was greater. In addition, the slotless nozzle is more capable of improving the surface roughness of the workpiece in the same time.
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