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Projects | |
14" F/4.5 Mirror Log
 | This article is an illustrated log of my notes taken while working on a 14" F/4.5 mirror for a Newtonian telescope. I have documented the progress (and problems encountered) and added photographs of the mirror at each major stage. Photos of the mirror's surface are being taken after each polishing session so that the results may be correlated to the methods used. (Note that this is a very long article covering a work in progress. It is over 500KB in length including the 90+ thumbnail images.) |
| Modular Optical Tester Design | This construction article describes how to build a compact, versitile head for your optical tester. Combine this with any mechanical base you chose and you have a tester that easily converts from Foucault to Ronchi to Wire testing in less than a minute. Other tests may also be supported by building specially modified versions of this assembly. |
Techniques | |
| Tile-On-Plaster Tools | Rather than using a glass tool for grinding and polishing, try making a plaster or concrete based tool. The plaster base may then be covered with hard porcelain floor tiles. Here is a description of how I make mine. This is an adaptation of the method used by Tom Waineo. |
| The "Dykem" Test | This is a variation on the "Sharpie Test" that I've developed to determine both quality of contact and number of pits remaining during fine grinding. |
| Fast Grinding and Polishing | There are a number of unusual techniques that are used to make grinding and polishing a mirror faster and easier. Presented here are a few of the techniques I have tried. Some worked for me, some didn't. Some may be of interest to other amateurs. |
| Making A Pitch Lap | There are as many ways to make a pitch lap for polishing as there are ATM's. This article shows the method that works best for me. It is a variation of the Hot Channel Pitch Cutter method. |
| Testing Quality Of Polish | This article describes the three most common amateur tests for determining when polishing is complete for a mirror surface. Described are the methods of direct inspection, the sun test, and the laser test. |
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Mirror Silvering
| For ATM's who want to try silvering their own mirror, this article describes the methods I used. It describes the chemical process and procedures as well as the construction of a "silvering station" I built to help ensure consistent results. |
| The Matching Ronchi Test | This article serves as a guide to the beginner in learning how to set up, use, and interpret the results of the Matching Ronchi Test. The Matching Ronchi Test is an ideal starting point for the beginning mirror maker. Here you can learn how to apply this simple test to your mirror. |
| Understanding The Foucault Test | This is a guest article by David Harbour. David provides a clear introduction to the Foucault Test for beginners using illustrations that make the test simple to understand and master. Using their new-found understanding of the Foucault Test as a starting point, beginners can then start to understand the other optical tests commonly used in mirror making. |
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Video Foucault Testing
| This article describes my implementation of Michael Peck's foucault data reduction method. Images captured with a Web camera or inexpensive video camera are processed to extract the Foucault Test data. Results using this method have proven to be unambiguous and very repeatable for me. |
| The Dall Null Test | When making non-spherical optics, a null test allows you to directly see how close you are to finishing. The Dall Null Test is one of the easier null tests to set up and use effectively. |
| Setting Up The Dall Null Test | Follow this tutorial to use the optical design program OSLO-LT to help you set up and simulate the Dall Null Test. Also use this powerful program to estimate the allowable tolerances in your test setup. |
Reviews | |
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