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Mounting 8, 10 and 12.5" Mirrors

The continuous face mirrors have a special mounting system that allows you to simply bolt the mirror to an adjustable mounting plate. No 'cell' in the traditional sense is required.  You get all the mounting hardware included with the mirror.

Below is a 10 inch mirror as set up for testing and evaluation. The mount is the simplest kind imaginable for a telescope mirror or laboratory application The mirror is held with a single 1/2" threaded rod screwed into a nut inserted into the back of the mirror. The face of the mirror is not perforated and there are no mirror clips interrupting the clean and continuous edge, and thereby creating significant diffraction.  This kind of mounting system is different than the typical cell in that the mirror is held firmly and will not drift around. Once the telescope is collimated it should not require constant collimation. The amateur wishing to build a first-rate telescope can construct such a mounting with no more than an electric drill and hand tools. The 8 inch mirrors mount in exactly the same manner except that they use a 3/8" bolt and nut. The principles are so evident and self-explanatory that extensive description is not necessary. The mirror comes with the mounting nut inserted and ready to mount. I supply the rest of the mounting hardware. Basically, you just drill a hole through the adjustable cell plate and screw it home.

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Fig. 8 - Hardware

Figures 1 shows a coated mirror mounted on a test stand in the shop. Figures 2 through 5 show the mounting method using a cutaway board representing a cell mounting plate. Note that the use of the compression spring on the mounting bolt is an absolute necessity. Without this spring, forces would occasionally build up though differential expansion that would distort the optical figure. Figure 8 shows the rod, washers, spring washers and nuts that you will get with the mirror. Figures 6 and 7 show this mirror under test. The test pictures are taken in autocollimation (double pass - null) with with a 133 line Ronchi grating. A very severe test. The surface is not only smooth but highly accurate after the insertion of the new mounting system. As you can see, there are no visible bends in the bands, and, it should be noted, the nut was set in after the mirror was figured. The hole you see in the middle in the test is an artifact of testing, the autocollimation flat. These mirrors have no holes in the front.

Here is something that the amateur telescope maker can make in a week-end and yield excellent results. Also, telescope manufacturers can modify their existing cells to accommodate this new and simple design.