The polishing stage of mirror making accomplishes two things. Amateur telescope making the designs range from simple to advanced, but all are within the range of a moderately wellequipped home workshop. The lens at the other end of the telescope is called the objective lens. Jan 18, 2017 the giant magellan telescope s third mirror is finely ground and polished at the university of arizonas mirror lab. Ive also read reports on printing the mask on paper with a laser printer and then transfering it to a glass using a hot iron method which is suitable for making a small mask for dslr or a refractor. This is the focus of all your work you will turn this flat piece of glass into an accurate parabolic telescope mirror. To learn more about mirror making at waite research, press like us on f acebook. Telescope making is at the heart of the springfield telescope makers after all it is two thirds of our clubs name and on these pages we hope to show you that you too can make your own telescope and it can be an excellent performer. Here is the result of firing the above stack of glass. Astronomers want increasingly large telescopes to peer into the depths of space.
Both are excellent low thermal expansion borosilicate glass. Practical calculations for designing a newtonian telescope. A beginner who wants an initiation into the techniques of mirrormaking and. Go inside a telescope mirror factory to a billionth of a. The testing of astronomical telescope mirrors page 3 the ronchi test in 1922 vasco ronchi proposed the test now named after him. The main difference is that it uses curved mirrors instead of lenses to collect the light. How to build an 80footwide telescope mirror to see deep. This step is about making one side of the glass concave. It probably came out no better than 12 wave i dont know i really didnt know how to test well yet. Making the giant magellan telescopes massive, incredibly. A reflecting telescope also called a reflector is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image. How to build a telescope go here for squirrelmail indian institute. The kit also contains enough pitch to make two pitch laps if you had to. Making a reflector telescope replica of the first reflector telescope built by sir isaac newton nowadays, professional astronomers use another type of telescope that is different to the first telescope invented the refractor telescope.
In the cassegrain, magnification by the secondary mirror is usually from 3x to 5x. First, it smooths the surface so that light can pass through or be reflected without scattering to form a clear, sharp image. The full set of issues 146 19781992 will cost you a little more than bucksus180. You can buy some ready made parts, or you can make everything on your own, including the mirrors and eyepieces.
Use a 1 12 secondary if this is your first telescope. The thicker the mirror, the longer it takes to adapt. I read several telescope and mirror making books and visited many amateur telescope making or atm websites to learn how to build a 14. If you are making this mirror to practice your skills for a future, large mirror you want to make, a fast, f4 f5 mirror is probably your best choice. The mirrors will fall out if you turn your periscope upside down. Incidentally, long focus telescope mirrors can be left spherical and work well, this is because at longer focal lengths the difference. The mirrorseyepiece light path has to be nice and straight. Telescope mirror blanks for amateur telescope makers.
I began building it in the spring of 2008, but the bulk of the work was done in july of 2008 with first light occurring on july 25. A 10inch telescope mirror has a 10inch or 250mm primary mirror. If you want to make a mirror that you will turn into your primary, visual use telescope. It is a finelooking, near fullthickness, 10 inch diameter blank that i intend to grind and polish into a 1st class telescope mirror. However, the price of the mirror increases as the mirror gets larger. Telescope making magazine atm, optics and diy forum. Jan 15, 2016 here at the mirror lab, we finished making the first giant magellan telescope segment in 2012. Beneath the university of arizona football stadium sits the steward observatory mirror lab. This page has formulas for many telescope and mirror parameters. This small book is intended to help people to make their own small telescope, having primary mirror of 150 mm diameter.
May 03, 2015 making a ceramic tile and dental plaster grinding tool for the 20 f4. Glass nearer the surface cools quicker than inside. Hold the periscope so the mirrors are resting on the wooden supports, then look through it. Cut a circle the same size of your telescope mirror and fold into quarters. There, giant mirrors are meticulously shaped and polished, to.
Building a telescope theory a b objective science and mathematics standards materials in a telescope, the lens held next to your eye is called the eyepiece and is usually a short focal length lens or a combination of lenses. Just a few basic parts like the primary mirror and the secondary mirror. This other kind of telescope can be over 10m in diameter. Jan 26, 2012 astronomers want increasingly large telescopes to peer into the depths of space. The book not only tells the reader what he can construct, but also what it is sensible to construct given what time is available commercially. Here is a stack of my homemade 8 and 10 inch mirror blanks. The plans call for a dowel 312 inches long, 4 inches wide. Buy a small tube of silicone glue and attach your secondary mirror to a 45 degree angle piece of steel drilled to accept a 14 bolt. The magnification is either blue or red, depending on whether it is below or above the likely maximum magnification of the telescope. The most elegant ways of building the mask are laser cutting, cnc or even 3d printing. This is attached to the vanes and becomes part of the spider.
The testing of astronomical telescope mirrors page 2 under the foucault test a parabolic mirror displays the socalled doughnut appearance, as the shadows produced resemble a doughnut. Telescope making magazine posted in atm, optics and diy forum. I made my first mirror when i was 14, a 6 f9 it was supposed to be an f8, but i had trouble getting the curve deep enough, by myself using thompsons making your own telescope. Mirror blank kit atm, optics and diy forum cloudy nights. To build a solid telescope mirror nearly 30 feet across, you need an oven that heats to 2,100 degrees fahrenheit.
More common is the richeychretien design, which combines particularly shaped primaries and secondaries to give a reasonably large field of view with reasonable. If the mirror is expanded to the size of a football field, then the mirror s surface will be smooth to 1 inch or millimeter. The light source is a slit which is reflected off the test optic, and the returning beam is allowed to pass through a transparent screen with a series of dark parallel. To build a simple reflector telescope and note its use of mirrors. Here at the mirror lab, we finished making the first giant magellan telescope segment in 2012. When the paper is unfolded, the hole will be in the exact center. The amateur can weigh all of this advice to find the instrument that corresponds to his or her needs. Plans for a dobsonian telescope plans for a homemade dobsonian telescope since you are reading this, you are probably considering to build your own dobsonian telescope. Each kit comes with a telescope mirror blank and all the abrasives silicon carbide grits and white aluminum oxide powders, cerium oxide polish and pitch to grind and polish it to your specifications. Telescope making basics 37 as for ccd cameras, the telescope s focal length determines the smallest angular detail that a ccd array can record. For our example, we will compute a 12 inch cassegrain of 20 ft. Pdf techniques of eighteenth century telescope makers, pt. This example is an exaggeration as the real movements are microscopic, but it will be enough to disturb the images seen through the telescope until the mirror temperature stabilises.
After a pause for work on two other mirrors, the lab is in the process of grinding segments 2 and 3. Even though some builders prefer to buy commercial mirrors and fit them in a diy structure, i believe that making a telescope mirror is probably the most rewarding part of the whole built. We will make our secondary magnification 4x, and the eyepiece will be 5 inches back of the face of the primary mirror. Amateur telescope making is the activity of building telescopes as a hobby, as opposed to being a paid professional. The picture shows the uk schmidt telescope at siding spring. Telescope making wikibooks, open books for an open world. Dec 01, 2014 beneath the university of arizona football stadium sits the steward observatory mirror lab. Telescope makers web ring home page this is the home page where you can list your web site and show off your creation. Perfect for making a high quality telescope mirror to your own specifications. Magnification focal length of primary lens or mirrorfocal length of eyepiece. But, when it comes to making the telescope there are a few things you have to be careful about. The diagonal mirror is glued to a section of 34 dowel and hung from a 18 threaded rod. Jackson the homemade telescopes power about 70 can reveal relief on the moons surface.
This page provides detailed plans and instructions how to build one. The reflecting telescope was invented in the 17th century, by isaac newton, as an alternative to the refracting telescope which, at that time, was a design that suffered from severe chromatic aberration. Making a telescope mirror is one of the most satisfying and sublime joys you will experience. Mel bartels amateur telescope making bbastrodesigns. We recommend a full thickness pyrex blank for mirrors up to to 12 in size. A beginner who wants an initiation into the techniques of mirrormaking and wants to have a goodquality instrument is welladvised to start by making a smalldiameter telescopethe mm whic h is described in chapter 6 beginning on page 85. Finally, the precision refractory molds for slumping the 42 inch mirrors in the kiln are proving too thin.
Starting from a rough glass blank, you can obtain an almost perfect parabola with surface errors in the range of 20 to 60 nm. This instructable describe the planning, design, and parts of the scope, as well as the process of building the scope. These will be used for making the vanes on the spider, to hold the secondary mirror in place. Hi all,i hesitate to mention this because it reeks of commercial endorsement, but i thought i might mention that kalmbach publishing has released the complete set of back issues of telescope making magazine in. A schmidt telescope puts a huge corrector lens in front of the primary mirror, to give acceptable images over an immense field. There, giant mirrors are meticulously shaped and polished, to be used in telescopes around the world. As each mirror is inserted, place a small piece of scotch tape over the mirror slots on the outside of the viewing tube. Bills homemade telescope making project this web page provides an overview of my large homemade telescope making project. The future, large mirror will also be something like f4. New listing edmund scientific first surface double sided mirror motorized keleidascope.
The mirror shows no astigmatism after polishing out on my mirror making machine, a major milestone. Its also arguably the most accurate surface made by man or machine. Grinding compound will make tool convex, mirror concave. Fullthickness means the diameter to thickness ratio is 6. The extra large secondary mirror will allow for lessthan perfect construction. With funding from the rockefeller foundation in 1928, he orchestrated the planning, design, and construction of the observatory, but with the project ending up taking 20 years he did not live to see its commissioning. Making a ceramic tile and dental plaster grinding tool for the 20 f4. It provides data to help in selecting a telescope, and also provides information necessary for mirror making and testing. The cage also serves as an exoskeleton to keep the tube rigid and thus to keep the telescope well collimated and aligned. Once out of the kiln, i removed it from the mold, and trued up the edge on my grinder. Jackson the homemade telescope s power about 70 can reveal relief on the moons surface. It will calculate parameters for two different telescope designs and compare the results for you. I bought a 4 foot length from the lumber yard in case i made mistakes.
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