A new type Stressed Mirror Polishing method using annular polishing machine is developed in NIAOT. It provides good efficiency for the massive production of off-axis segments for the extremely large telescope because 3 or more pieces of segment can be polished simultaneously on a AP machine. With an annular polishing machine with 3.6m diameter, two scale-down TMT segments have been polished. Both 2 segments are Φ1100mm in diameter, with the vertex radius of curvature of 60m and aspheric constant K=-1.000953. The off-axis distances (OAD) are 8m and 12m respectively. After SMAP process, the acceptable surface accuracy can be reached, which is 1.12μm/0.23μm of PV/RMS value for the segment with 8m OAD, and 1.22 μm/0.26 μm for another one.
When polishing and modifying the large aperture flat by the traditional polishing tools, people usually test it by
a spherical mirror as a standard surface which been called the Ritchey-Common method, that not only can
break through the limitation of the aperture, but also can achieve high precision wave front if the surface of the
standard mirror is perfect. However, when doing ultrahigh precision modifying by the modern polishing
equipment such as: ion beam polishing, this testing method cannot meet the need of the high precision
location, because of the error caused by the nonlinear transformation of the coordinate, the testing result
usually cannot been very exactly developed point to point, that restrained the polishing accuracy. Here the
error has been studied in order to exactly developing the testing result. At first, in principle, the Ritchey-
Common testing path has been analyzed in detail. Secondly, the point to point transfer equation has been
deduced, and some feature points have been chosen to help analyze the relationship between the object
surface and the image result. Then a program has been written according to the deduced equation, by which
the image can be well developed. Finally the error has been compared by using different developing methods
in the experiment. The study can solve the nonlinear point to point transfer and location problem caused by
the Ritchey-Common testing method, so when manufacturing the large aperture flat, the Ritchey-Common
testing method can be used in the ultrahigh precision polishing.
The test method of Large-diameter convex secondary mirror in development process is the key to making large
telescope technology. Classical means HINDLE to test using of non - aberration points needs a spherical reflecting
mirror which larger than the secondary mirror several times. This new Hindle test method based on stitching
technology can significantly reduce their standard mirror's size, drop the difficulty of processing and cut down the
costs. In This paper, the Hindle testing basic principles which base on stitching technology is introduced firstly, then
principle of stitching and least square method. Following the parameters of inside and outside standard mirrors are
derived. Then translation and rotation transformation algorithm of different sub-aperture interferometer array data is
given. Finally the preliminary results of the radial stitching experiments are given. The results showed that the relative
error is RMS = 6.1%, PV = 5.11%. With improving and perfection, this method can be used in the E-ELT, CFGT
convex secondary mirror telescope test.
Nowadays many large aperture optical components are widely used in the high-tech area, how to test them become more
and more important. Here describes a new method to test the large aperture optical components using the small aperture
interferometer, deduce how to get the aperture number and the concrete process of the stitching parameter in a systematic
way, finally get the best plan to choose the sub-aperture of the square and circular optical plane. To specify the stability
of the method we operate an experiment, the result shows that the stitching accuracy can reach λ/10, it meet the need of
the inertia constraint fusion etc, that is good enough to be used in the high-tech area.