Polishing of the mirror and give it the desired shape is obviously the most difficult stage in the whole construction of the telescope; this follows from the need to give the mirror telescopic aspherical shape with very high accuracy. I, if mirror grinding, its shape did not have a big impact, This case is when polishing is quite different – polished glass on the pitch, somewhat flexible, “flowing” during the polishing. From the selection of its hardness depends largely on the success or failure of the whole fun in polishing the mirror to the telescope. Many people achieve the appropriate hardness by adding to the melting tar rosin. Then, the molten mixture is put spatula, embedded tar-water cooling and pressing, eg. watch toenail, and is followed. I personally advise you to buy a ready-pitch optical. We then guarantee, that during the melting and mixing with rosin not fall to us to involve any, even the smallest trash. And any hard-ons embedded in the tar that cause our telescope mirror will be quite heavily scratched.
The finished optical tar pitch at least I can recommend the brand “Gugolz” or numerach 55 do 64. Higher numbers correspond to the already very hard smołom, unlikely to be used in ATM.
Once we have tar- , it must be dissolved in a clean metal bowl, always being careful not to get into the pollution. The plate on which we polerownik thoroughly wash and dry. Taped to the edge of the plate with several layers of paper tape (adhesive) so that the pitch has drained us of the plate. After pouring tar, It should impress on (sanded to a powder 800 or finer) mirror. This must be done very carefully, so that the mirror is not to tar przylepiło. I personally always wait until the surface creates a “raft” of tar zastygniętej. Additionally, you can cover the surface of the mirror with a thin layer of the telescopic suspension polishing powder. It is important, that we were able to exactly match the pitch of the mirror, if this fails at the first attempt, tar is worth a little heated, eg by means of hot water, lamp with a strong energy-saving bulb is not, or even a burner with caution. When the pitch will accordingly Plastic, mirror again pressed against her. If we consider now, that mirror duly wrong to tar, This should be on the cut grooves, becoming like a bit of tar to the surface of chocolate. The grooves are similar to the tire tread- drain excess slurry polishing powder and allow the hurt to the tar surface of the mirror during polishing. With proper practice, you can pitch scored differently, However, for beginners of this method is most appropriate. While undercutting tar, particles of it are able to adhere odpryskujące Hand. The easiest way to wash them in very cold water. Tar loses flexibility and is easier then walks away from the skin. Use very hot water will cause the pitch will become sticky and clog very effectively with our hands. Then the easiest domyć it with gasoline and turpentine (not mixed together). When the pitch is ready, begin to shine. There is some similarity to the grinding, long movements of the mirror to reduce the focal pitch, short movements can be extended. putting tar on the top and bottom of the mirror will also focus on extending.
At the end, unfortunately, the analogy with the grinding. Because the pitch is flexible, mirror does not need us to polish while maintaining the spherical shape. I really can not be given ready-made recipes to mirror movements in the pitch, to maintain the desired shape. You have to experiment yourself. Some polish the mirror to remove completely the remaining pits after the cut and then try to get the sphere. I personally advise you to check the mirror from the beginning in terms of deviations from the sphere. This will save a lot of trouble, will advance to correct movements and appropriate intervention in the form of tar. And if for example we see , that in our time polishing the mirror in the middle of the hole formed, to measure tar lightly scratch with a knife. Similarly,, if we are tucked up ashore, This should shore tar scratch. Interference in pitch must be very delicate, so, during polishing to pitch again put together over time to the shape of the mirror. It is important to control and correct assessment of whether our mirror is polished and has not been any holes after sanding powder. Very helpful here is a good light and magnifier with a magnification of about 8-10x. It is difficult to describe the proper way to control but it is more or less on observation with a magnifying glass surrounding the light reflectance of the mirror surface. Any small dots observed through a magnifying glass are saying about the need for further polishing. I would add,spraying such that the mirror, only highlight any shortcomings in the polishing. The mirror in this place is simply dull. …
As I mentioned, worth from the very beginning of the polishing of the mirror to check on the knife and did not allow for too much deviation from the sphere. How to interpret the images with a knife Foucalt,and very well described by Janusz Wiland on your site: http://www.astrojawil.pl / jazzz.htm.