Reflector telescope design montana state university. Engineering lightweight dobsonian telescopes 20 update. To build a simple reflector telescope and note its use of mirrors. The main difference is that it uses curved mirrors instead of lenses to collect the light. Making a mirror grinding tool by allen malsburry the average person would never think, i can make my own telescope. The 18 mirror segments will form the webb telescope s huge primary mirror. Large mirrors are structurally easier to design and less expensive to build than large lenses. 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. An amateur telescope builder reveals his process for designing and constructing his own dobsonian telescope using cad design and a cnc router. The idea that the objective, or lightgathering element, could be a mirror instead of a lens was being investigated soon after the invention of the refracting telescope. Part 1 includes prepping the mirror for grinding, spherometry on the.
This is because the secondarys conic constant, k s is a function of how far it is from the primary mirror and the distance to the focal plane. Now i am building a 10 reflector for astrophotography. Telescope making basics 37 as for ccd cameras, the telescope s focal length determines the smallest angular detail that a ccd array can record. How to make a reflector telescope storm the castle. Place the paper template on the front surface of your telescope, making sure it is centered. 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. This other kind of telescope can be over 10m in diameter. Grinding compound will make tool convex, mirror concave. Engineering, design and construction of portable newtonian telescopes, advanced telescope making techniques volume 1 optics, advanced telescope making techniques volume 2 mechanica, a manual for amateur telescope makers, amateur telescope making, the best of amateur telescope making journal, build your own telescope, the dobsonian telescope, how to make a telescope, introduction to lens design. When the paper is unfolded, the hole will be in the exact center. These sources of information provided many of the techniques i used to make the telescope. Amateur telescope making the designs range from simple to advanced, but all are within the range of a moderately wellequipped home workshop. Amateur telescope makers sometimes called atms build their instruments for personal enjoyment of a technical challenge, as a way to obtain an inexpensive or personally customized telescope.
Before undertaking the construction of a telescope, ask yourself some questions. The joy of mirror making mel bartels rough grinding the first milestone is putting a curve into the mirror face. I read several telescope and mirror making books and visited many amateur telescope making or atm websites to learn how to build a 14. Telescope making magazine atm, optics and diy forum. Angel is the master of making big mirrors for telescopes. University of arizona is making gigantic mirrors for world. For each telescope, the cost data point was intended to be inclusive of telescope mirror, structure, enclosure, and other essential site work based on these references, and exclusive of instrumentation and operations cost. There are 18 segments, because it takes a large mirror. One of the classics in building your own reflecting telescope. Clark, amateur telescope making in the internet age, patrick moores. How to build an 80footwide telescope mirror to see deep. That would make a 150 mm f8, or a 200 mm f6 mirror.
This web page provides an overview of my large homemade telescope making project. They found use in terrestrial applications and astronomy. How do you turn a chunk of glass into a telescope mirror. Once youve gotten the two mirrors and the eyepiece, you can begin constructing the telescope tube. The curves depth dictates the mirror s focal length. The correction of a cassegrain optical system with an aspheric secondary mirror classical, rc is dependent on the primarysecondary distance. 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 extra large secondary mirror will allow for lessthan perfect construction. Pioneered technique of making huge mirrors on honeycomb substrates. Grinding moving the mirror over the tool with grit between.
Applying a reflective coating to large astronomical telescopes is a costly procedure and. Go inside a telescope mirror factory to a billionth of a. Fig 1 this is a large piece of glass a woman off craigslist gave me. For a given aperture, the larger the focal ratio the larger the focal length, the shallower the mirror surface. Instructions for silvering an 8inch mirror cs department. Mirror blanks are individually tested for internal strain. Nasas james webb space telescope the james webb space telescope is the nextgeneration premier space observatory that will explore deep space phenomena from distant galaxies to nearby planets and stars.
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. If the mirror is expanded to the size of a football field, then the mirrors surface will be smooth to 1 inch or millimeter. Its also arguably the most accurate surface made by man or machine. Stepbystep instructions spray silvering telescope mirrors. There, giant mirrors are meticulously shaped and polished, to be used in telescopes around the.
Again, john dobsons telescope making video listed in sources shows the construction of a 16 telescope with this modified tube box and support system. The important basic dimensions of a cassegrain telescope are. The goal is to make the outside edge of the secondary mirror appear concentric with the inside diameter of the end of the sight tube, as seen through the peep hole. This book will expertly guide you through every step of design, construction, and mirror making. Cost data were normalized to year 2000 us dollars using the standard. You have probably seen a telescope before, and wondered how it works.
Here at the mirror lab, we finished making the first giant magellan telescope segment in 2012. I used this book, amongst others, to build my first scope which was an 8 reflector. We grind and polish to a sphere, then figure to a parabola. Researchers believe that, as new mirror coating technologies are developed, they can provide increasing positive benefits when applied to optical mirrors in new telescopes. Telescopes are important in astronomy because they do two things extremely well. The following is taken from the standard handbook for telescope making by neale howard. Practical calculations for designing a newtonian telescope. Covers all aspects of mirror making, and directions for making diagonal flats, perforated primaries and optical windows.
Amateur telescope makers sometimes called atms build their instruments for personal enjoyment of a technical challenge, as a way to obtain an inexpensive or personally customized telescope, or as a research tool in the field of astronomy. Here is a link to where i bought this primary mirror and secondary mirror pair on ebay. Again, john dobsons telescope making video listed in sources shows the construction of a 16 telescope. Jan 18, 2017 the giant magellan telescope will feature seven enormous mirrors and one spare each a precisely engineered piece of glass 27. Amateur telescope making is the activity of building telescopes as a hobby, as opposed to being a paid professional. Just a few basic parts like the primary mirror and the secondary mirror.
Telescope mirror blanks providing telescope mirror blanks and kits to telescope makers. Jan 22, 20 galileo heard about the dutch telescope in june 1609, built his own within a month, and greatly improved upon the design in the following year. This book shows how to grind and lap your own mirror and the other essentials involved in build your scope. Web suppliers of telescope building parts and materials. For 30 years he has been using a method called spin casting to make the largest solid telescope mirrors in the world. May 28, 2016 documenting the telescope build, including mirror grinding and figuring, and construction of the renegade telescope body. 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. How to make your own telescope mirror instructables. If the mirror is expanded to the size of a football field, then the mirrors. Nowadays, professional astronomers use another type of telescope that is different to the first telescope invented the refractor telescope. 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. If you want to make a mirror that you will turn into your primary, visual use telescope, 1200 mm focal length would be recommended. Secondary mirror offset to avoid a loss in optical path at the edge of the secondary mirror that pointed towards the primary mirror, some atm ers find it necessary to mechanically shift the secondary mirror away from the focuser and towards the primary mirror.
It provides data to help in selecting a telescope, and also provides information necessary for mirror making and testing. Making the giant magellan telescopes massive, incredibly. Several forces have come together recently to make spray silver coatings an attractive option for telescope mirrors again, especially those 12inches and larger in diameter. Because the mirror s focal length is large in relation to the mirror s diameter, in other words, the focal ratio is large, the difference between sphere and parabola is very little. Telescope making magazine posted in atm, optics and diy forum. Making a telescope mirror is one of the most satisfying and sublime joys you will experience. This page provides detailed plans and instructions how to build one. Now you need to decide about the focal length of your future mirror.
A beginner who wants an initiation into the techniques of mirrormaking and. Engineering, design and construction of portable newtonian telescopes, advanced telescope making techniques volume 1 optics, advanced telescope making techniques volume 2 mechanica, a manual for amateur telescope makers, amateur telescope making, the best of amateur telescope making journal, build your own telescope, the dobsonian telescope, how to make a telescope. 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. Within a few decades, the reflecting telescope was invented, which used mirrors. You can buy some ready made parts, or you can make everything on your own, including the mirrors. Telescope newtonian reflector the newtonian reflector, also known as catoptrics, is a telescope which uses a spherical or concave parabolic primary mirror to collect, reflect and focus the light onto a flat secondary mirror diagonal. That detail must cover a minimum of two pixels on the ccd array to be discernible. It is said that elliptical mirror is needed but instead of that can i use rectangular glass to make it as a secondary mirror. Cut the four sides out of a quarter sheet of 38 ac exterior plywood, guided by the dimensions. 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 scaling relationship between telescope cost and aperture.
The third telescope is a 300mm f12 cassegraincoude with four optical components. It will calculate parameters for two different telescope designs and compare the results for you. Compared to the american mirror making books of the 1950s, texereaus was more surefooted in its discussion of the diffraction effects in telescopes. Today, with the lowcost imported telescopes, making your own telescope. Pdf techniques of eighteenth century telescope makers, pt. For such telescopes arrays probably tens of thousands of optical mirror panels. The lens at the other end of the telescope is called the objective lens. The plans call for a dowel 312 inches long, 4 inches wide. Large mirrors are structurally easier to design and less. The first known practical telescopes were invented in the netherlands at the beginning of the 17th century, using glass lenses. Nasas james webb space telescope s 18 special lightweight beryllium mirrors have to make 14 stops to 11 different places around the u. It is reproduced here without permission from the original. The mirrorseyepiece light path has to be nice and straight. The full set of issues 146 19781992 will cost you a little more than bucksus180.
Silver coating on large telescope mirrors tutorial. Secondary mirror making posted in atm, optics and diy forum. 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. Plastic protractor inserted under a 6 inch mirror blank during a stress test, to illustrate what stress would look like if there were any present. The amateur can weigh all of this advice to find the instrument that corresponds to his or her needs. But, when it comes to making the telescope there are a few things you have to be careful about. G of the whole telescope is the center around which the e. These will be used for making the vanes on the spider, to hold the secondary mirror in place. Starting from a rough glass blank, you can obtain an almost perfect parabola with surface errors in the range of 20 to 60 nm. May 03, 2015 making a ceramic tile and dental plaster grinding tool for the 20 f4. Cutting it into smaller sections can be difficult but scoring it with a glass cutter and tapping t. To build a solid telescope mirror nearly 30 feet across, you need an oven that heats to 2,100 degrees fahrenheit. For many decades now, amateur astronomers have been building their own telescopes.
Replica of the first reflector telescope built by sir isaac newton. After a pause for work on two other mirrors, the lab is in the process of grinding segments 2 and 3. Shankar this small book is intended to help people to make their own small telescope, having primary mirror of 150 mm diameter glossary of symbols 1. Their large lenses and mirrors can collect much more light than the human eye, which make. I bought a 4 foot length from the lumber yard in case i made mistakes. Jan 26, 2012 astronomers want increasingly large telescopes to peer into the depths of space. Beneath the university of arizona football stadium sits the steward observatory mirror lab.
With about 50 videos on mirror making and telescope building, gordons youtube channel has accumulated almost 1,500,000 views. Objective mirrors are easier to make than objective lenses. If you are thinking about moving up to a large aperture telescope mirror, well fabricate a premium 20 mirror. Cut a circle the same size of your telescope mirror and fold into quarters. 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.
This page has formulas for many telescope and mirror parameters. B the separation between the primary and the secondary. New listing edmund scientific first surface double sided mirror motorized keleidascope. Use a 1 12 secondary if this is your first telescope. This will surround the secondary mirror with a white background, making it easy to see where the edge of the mirror is. How to make a telescope second english edition english. Caris mirror laboratory at the university of arizona is the only place in the world that can produce 27foot mirrors for telescopes. For telescopes with mirror diameters 16 and larger, a different tube box design and mirror support system is necessary. Ota 5 keep the tracking wheels inside the base ground legs and min.
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