Choosing a Telescope
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Sky & Telescope
S&T Test Report by Rod Mollise Meade’s 115-Millimeter ED Triplet This 4.5-inch apochromat packs a lot of bang for the buck. 115mm Series 6000 THIS IS A GREAT TIME to be in the ice and was eager to see how others market for a premium refracting tele- performed. So when I was approached ED Triplet APO scope. The price for high-quality refrac- about evaluating Meade’s 115mm Series U.S. Price: $1,899 tors has fallen dramatically in recent 6000 ED Triplet APO, I was certainly up meade.com years, and you can now purchase a for the task. 4- to-5-inch extra-low dispersion (ED) First impressions are important, and What We Like apochromatic (APO) telescope that’s when I unboxed the scope on the day Sharp, well-corrected optics almost entirely free of the false color it arrived, I lit up when I saw it. This is Color-free views that plagues achromats for a fraction of Attractive fi nish the cost commonly seen a decade ago. I’ve had a ball with my own recently q The Meade 115mm Series 6000 ED Triplet What We Don’t Like purchased apochromat after using APO ready for a night’s activity, shown with an optional 2-inch mirror diagonal. The scope Visual back locking almost nothing but Schmidt-Cassegrain also accepts fi nderscopes that attach using a system can be awkward telescopes for many years. However, I standardized dovetail system commonly found Focuser backlash still consider myself a refractor nov- on small refractors. -
A DESCRIPTION of FOUR FAST SLITLESS SPECTROGRAPHS by Gale A
A DESCRIPTION OF FOUR FAST SLITLESS SPECTROGRAPHS by Gale A. Hawey kngley Research Ceater Langley IStation, Hampton, Va. I .I NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTO 0CT.OBER 1967 , 8l .~ -. .y-; $. .Ir* *. r., \. ',r <'. /. ., ..., I 5,, 2 .,i c, . B TECH LIBRARY KAFB, NM . -- 0130742 NASA TN D-4145 A DESCRIPTION OF FOUR FAST SLITLESS SPECTROGRAPHS By Gale A. Harvey Langley Research Center Langley Station, Hampton, Va. NATIONAL AERONAUTICS AND SPACE ADMINISTRATION For sale by the Clearinghouse for Federal Scientific and Technical Information Springfield, Virginia 22151 - CFSTl price $3.00 A DESCRIPTION OF FOUR FAST SLITLESS SPECTROGRAPHS By Gale A. Harvey Langley Research Center SUMMARY A description, comparison, and short discussion of four fast slitless spectrographs for use in low-light-level research are given. The spectrographs include three catadiop- tric systems, the Super Schmidt meteor camera, the Baby Schmidt, and the Maksutov and one refractive optical system, the Super Farron. The Baby Schmidt and the Maksutov systems have fused-silica transmission elements. Except for the Super Schmidt camera, which utilizes a light flint mosaic prism, all systems utilize objective transmission dif- fraction gratings. The four systems discussed have low-light-level spectroscopic recording capability, The Super Schmidt has the largest field, 57'; the Baby Schmidt and Maksutovs have the broadest effective spectral range (3200 angstroms to 9500 angstroms); and the Super Farron features the greatest versatility and portability. INTRODUCTION A spectrograph is an apparatus which effects dispersion of radiation for photo- graphic recording. A slitless spectrograph consists basically of a dispersion element, prism, or grating, placed over the entrance of a camera so that images or the radiation source rather than the entrance slit of the more customary slit spectrograph are formed. -
A Theory of Catadioptric Image Formation * Simon Baker and Shree K
A Theory of Catadioptric Image Formation * Simon Baker and Shree K. Nayar Department of Computer Science Columbia University New York, NY 10027 Abstract able is that it permits the generation of geometrically Conventional video cameras have limited fields of correct perspective images from the image(s) captured view which make them restrictive for certain applica- by the catadioptric cameras. These perspective images tions in computational vision. A catadioptric sensor can subsequently be processed using the vast array of uses a combination of lenses and mirrors placed in techniques developed in the field of computational vi- a carefully arranged configuration to capture a much sion which assume perspective projection. Moreover, if wider field of view. When designing a catadioptric sen- the image is to be presented to a human, as in [Peri sor, the shape of the mirror.(s) should ideally be selected and Nayar, 19971, it needs to be a perspective image in to ensure that the complete catadioptric system has a order to not appear distorted. single effective viewpoint. In this paper, we derive the In this paper, we begin in Section 2 by deriving the complete class of single-lens single-mirror catadioptric entire class of catadioptric systems with a single effec- sensors which have a single viewpoint and an expres- tive viewpoint and which are constructed just using a sion for the spatial resolution of a catadioptric sensor single conventional lens and a single mirror. As we will in terms of the resolution of the camera used to con- show, the 2-parameter family of mirrors which can be struct it. -
ALD13 Advanced Lens Design 13
Advanced Lens Design Lecture 13: Mirror systems 2013-01-21 Herbert Gross Winter term 2013 www.iap.uni-jena.de 2 Preliminary Schedule Paraxial optics, ideal lenses, optical systems, raytrace, 1 15.10. Introduction Zemax handling Basic principles, paraxial layout, thin lenses, transition to 2 22.10. Optimization I thick lenses, scaling, Delano diagram, bending 3 29.10. Optimization II merit function requirements, effectiveness of variables 4 05.11. Optimization III complex formulations, solves, hard and soft constraints zero operands, lens splitting, aspherization, cementing, lens 5 12.11. Structural modifications addition, lens removal Geometrical aberrations, wave aberrations, PSF, OTF, sine 6 19.11. Aberrations and performance condition, aplanatism, isoplanatism spherical correction with aspheres, Forbes approach, 7 26.11. Aspheres and freeforms distortion correction, freeform surfaces, optimal location of aspheres, several aspheres 8 03.12. Field flattening thick meniscus, plus-minus pairs, field lenses Achromatization, apochromatic correction, dialyt, Schupman 9 10.12. Chromatical correction principle, axial versus transversal, glass selection rules, burried surfaces 10 17.12. Special topics symmetry, sensitivity, anamorphotic lenses high NA systems, broken achromates, Merte surfaces, AC 11 07.01. Higher order aberrations meniscus lenses Advanced optimization local optimization, control of iteration, global approaches, 12 14.01. strategies growing requirements, AC-approach of Shafer 13 21.01. Mirror systems special aspects, bending of ray paths, catadioptric systems color correction, straylight suppression, third order 14 28.01. Diffractive elements aberrations 15 04.02. Tolerancing and adjustment tolerances, procedure, adjustment, compensators 3 Contents 1. General properties 2. Image orientation 3. Telescope systems 4. Further Examples 4 General Properties of Mirror Systems . -
31 the Superachromat
Lesson 31: The Superachromat This lesson will explore a unique feature of SYNOPSYS that can be helpful when you need exceptional color correction, better even than an apochromat. Lesson 8 in this Online Tutorial showed how to select three glass types that make it possible to correct axial color at three wavelengths. For many tasks, that is as good as you will need. But not always. Suppose you are designing a lens to be used over the range 0.4 to 0.9 um. Can you do it with an apochromat? Let’s find out. Here is the RLE file for a starting system, where all surfaces are flat except for the last, which will give us an F/8 telescope objective of 6-inch aperture. (Copy these lines and paste them into the MACro editor.) RLE ID WIDE SPECTRAL RANGE EXAMPLE OBB 0 .25 3 UNITS INCH 1 GLM 1.6 50 3 GLM 1.6 50 5 GLM 1.6 50 6 UMC -0.0625 YMT 7 1 TH .6 2 TH .1 3 TH .6 4 TH .1 5 TH .6 END We did not specify the wavelengths yet, so we get the default CdF lines. We need to change this. Open the Spectrum Wizard (MSW), and change the points indicated. 1 After clicking the Get Spectrum button, click the Apply to lens button. Our lens now has a wider spectrum. Here is our starting lens, in the SketchPad display Uggh! Yes, it’s really awful. Let’s optimize it, varying the glass models. Make a MACro: LOG STO 9 PANT VLIST RAD 1 2 3 4 5 VLIST TH ALL AIR VLIST GLM ALL END AANT END SNAP SYNOPSYS 50 Now put the cursor on the blank line after the AANT command, and click the button . -