DOCSLIB.ORG

Telescopes and Optics

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Telescopes and Optics TelescopesandOptics SurveyofAstronomyA110 TelescopesandOptics • Goals – Howdotelescopeswork? – Howdoastronomersutilize telescopes? – Whydowemoveintospace? • PrincipalsofOptics – Refraction Figure6-1 • Lighttravelsslowerindensematerials. • c=3x108 ms-1 (vacuum) • c=2x108 ms-1 (glass) • Lightpassingfromonemediumtothe next(e.g.airtoglass)canchangethe directionofthelight. • Thisiscausedbythechangeinthe velocityoflight. TelescopesandOptics SurveyofAstronomyA110 • RefractionandLenses Figure6-2,6-4 – Refractionenablesalenstofocuslight • Lightincidentonlensisrefractedbyan angleα. • Lightleavingthelensisrefractedbyan angle-α. • Curvedlensescanfocusordisperselight. – Lenses • Convexlensesfocusparallelraysoflight toacommonfocalpoint. • Concavelensesdisperseparallelraysof light. • Focallength ofalensisthedistancefrom thelenstothepointwherethelightfroma parallelbeamisbroughttoafocus. • Focalplane istheplaneontowhichan extendedimagewillbebroughttoa commonfocus. – LightfromGalaxiesandStarsis Parallel. TelescopesandOptics SurveyofAstronomyA110 • RefractingTelescope – ASingleLens • Aswithacameraoryoureyeasinglelens willbringanimageintofocusatthefocal plane(filmoryourretina). • Toviewtheimage(notapictureofthe image)yourequireasecondlens(or projectontoascreen). – DoubleLensSystem Figure6-5 • Secondlensmagnifiestheimage. • Objectivelens:largerlens,largerfocal length,formstheimage. • Eyepiecelens:smallerlens,smallerfocal length,magnifiestheimage. angulardiameterthrougheyepiece Magnification= angulardiameterbyeye focallengthoftheobjectivelens = focallengthoftheeyepiecelens TelescopesandOptics SurveyofAstronomyA110 • RefractingTelescope – Magnificationandlightgathering • Mostimportantaspectofatelescopeisthe amountoflightitcancollect. Lightgatheringpower∝areaoflens ∝diameter 2 • Morelight:fainterobject(e.g.eye’spupil) • Limitonmagnificationistheatmosphere. – Example:RefractingTelescope • Objectivefocallength=120cm • Eyepiecefocallength=4cm 120cm Magnification= =30(30x) 4cm • Magnificationpoweriswrittenas30x • Ifaneyepieceof2cmfocallengthisused themagnificationis60x. • Shorterthefocallengthoftheeyepiece (orlongerthefocallengthoftheobjective lens)themoremagnification. TelescopesandOptics SurveyofAstronomyA110 • Aberrations – Chromaticaberration Figure6-7 • Therefractionoflightbyalensdepends onitswavelength. • Differentwavelengthsarebroughtto focusatdifferentfocalpoints. • Onlyonewavelengthwillbeinfocusanda coloredhalowillresult. • Combininglayersofglasscanresolvethis. – SphericalAberration Figure6-13 • Asphericalmirrordoesnotbringlightto acommonfocusatthesamepoint(a curvedfocalplane).Thisresultsinafuzzy image. • Parabolicmirrorssolvethisproblembut atthecostoffieldofview. • Ifthemirrordoesnothaveacommon focallengthatallpointsthelightisnot broughttofocusatacommonfocalplane (e.g.HubbleSpaceTelescope). TelescopesandOptics SurveyofAstronomyA110 • Refractingvs ReflectingTelescopes – Earlytelescopes(<1900s) • Refractingtelescopesusing2lenses(e.g. Galileo). • Largerthelensthefaintertheobjectswe canview. • Largelensesrequirelargefocallengths (shortfocallengthsarehardtomake). • Largedefectfreelensesarehardto manufacture- largestlensmade(Yerkes) is102cm(19.5mfocallength). • Lensarenotveryefficient. – NewerTelescopes(>1900s) • Usemirrorsinplaceoflenses. • Largestmirrorsare8minsize. • “Easy”toconstructshortfocallengths. • Mirrorsareveryefficient(99%). • Easytosupport. TelescopesandOptics SurveyofAstronomyA110 • ReflectingTelescopes Figures6-9,6-10 – ReflectingSurface • Lightincident toaflatreflectingsurface atanangleα totheperpendicularis reflected atanangleα. – AReflectingCurvedSurface • Aconcavereflectingsurfacewillbring lighttoacommonfocus. • Focallength ofamirroristhedistance fromthemirrortothepointwherethe lightfromaparallelbeamisbroughttoa focus. • Theobjectivemirroriscalledaprimary mirror. • Nochromaticaberration. • Lightisfocusedinfromofthemirror- needto“pickoff”theimage. • Pickoffmirroriscalledthesecondary. TelescopesandOptics SurveyofAstronomyA110 • TypesofReflectingTelescopes Figure6-11 – Newtonian • Beamispickedoffbya45o flatmirror. • Earliestreflectingtelescopedesign. – PrimeFocus • Detectorisplacedwithinthebarrelofthe telescope. • Limitsthenumberofreflections. – Cassegrain • Lightisreflectedbackdownbyaconcave secondarymirror. • Lightpassesthroughtheprimary. • Mostcommondesign- shorttube. – Coude • LightReflectsoffthesecondary. • Lightispickedoffbyatertiarymirror. andreflectedtothepivotpoint(Nasmyth) ofthetelescope. TelescopesandOptics SurveyofAstronomyA110 • ReflectingTelescope – ImageScale • Atelescope'sfocallengthdeterminesthe scaleofanimageformed. – Imagebrightness • Thetelescope'sf-valueorfocalratio(i.e., focallengthdividedbydiameter) determinesimagebrightness. – Obscurationduetosecondary • Secondarymirrorblockssomeofthelight fromreachingthemirror. • Secondarydoesnot blockpartofthe image(lightfromasourcecomesfromall angles). TelescopesandOptics SurveyofAstronomyA110 • Howwellcanwesee? – Imagequalityislimitedbythe atmosphere(e.g.twinklingstars) • Theatmosphereisturbulent. • Lightpassingthroughtheatmospheregets refractedandthepathsofphotonsarenot thesame. • Thesizeofapointsourceduetothe blurringoftheatmosphereiscalledthe seeingdisk(0.5- 1arcsec). – Telescopesizelimitsresolution • Howwellwecanseparatetwoclose sources(angularresolution)dependson telescopesize. λ θ =2.5x105 D θ :diffractionlimit(arcseconds) λ :wavelength(m) D :primarymirrordiameter(m) • Longerwavelength→ worseimages. • Biggertelescopes→ betterimages. TelescopesandOptics SurveyofAstronomyA110 – Example:(1mtelescopeat500nm) λ θ = 2.5x105 D 600x10-9 =2.5x105 1 = 0.15arcsec • Evenwitha1metertheatmospherelimits howwellwecanresolveobjects. 10mtelescope θ = 0.015arcsec – Adaptiveoptics • Wecancorrectfortheturbulenceby deformingtheprimary/secondary mirrors. • Equivalenttocorrectingthewavefront of thelight. TelescopesandOptics SurveyofAstronomyA110 • Detectors – Photographicplates • Usedforimagingfrom1900sto1980s. • Lowsensitivity(2%efficiency). • Non-linearreaction(exposureT intensity). • Widefield(5degrees). – ChargeCoupledDevices(CCDs) • Usedinimagingfrom1980s. • Highsensitivity(70-90%). • Linearrelationbetweenphotonsand signal. • Similartodigitalcameras(runat-90oC). • Largefields(1degreemosaics). TelescopesandOptics SurveyofAstronomyA110 • NewWavelengths – RadioTelescopes • Stars,galaxiesandgasemitatradio frequencies- synchrotronradiation. • Easiertobuild- surfaceoftelescopedoes notneedtobeasaccurate(1/10thofa wavelength). • Dishesmadeofwireandmetal. • Resolutionpoorer. λ 0.20 θ = 2.5x105 = 2.5x105 D 10 =1.4degrees • Useinterferometry toimproveresolution. • Resolutiondeterminedbythelargest distancebetweentelescopes(i.e.their separation). • Observethroughcloud,daytime,rain. TelescopesandOptics SurveyofAstronomyA110 – Space-basedObservatories Figure6-27 • Transparencyoftheatmosphereisnota problem(ultravioletandfar-infrared). • Atmosphericturbulenceisnotaproblem (diffractionlimitedimages). • Skybackgroundislower. • NASA’sGreatObservatoriesProgram HubbleSpaceTelescope(UV,optical,andIR)1990. GammaRayObservatory[Compton]1991. AdvancedX-RayAstronomicalFacility[Chandra]1999. SpaceInfraredTelescopeFacility[SIRTF]2003..
Load more

Recommended publications
  • Determination of Focal Length of a Converging Lens and Mirror
    Physics 41- Lab 5 Determination of Focal Length of A Converging Lens and Mirror Objective: Apply the thin-lens equation and the mirror equation to determine the focal length of a converging (biconvex) lens and mirror. Apparatus: Biconvex glass lens, spherical concave mirror, meter ruler, optical bench, lens holder, self-illuminated object (generally a vertical arrow), screen. Background In class you have studied the physics of thin lenses and spherical mirrors. In today's lab, we will analyze several physical configurations using both biconvex lenses and concave mirrors. The components of the experiment, that is, the optics device (lens or mirror), object and image screen, will be placed on a meter stick and may be repositioned easily. The meter stick is used to determine the position of each component. For our object, we will make use of a light source with some distinguishing marking, such as an arrow or visible filament. Light from the object passes through the lens and the resulting image is focused onto a white screen. One characteristic feature of all thin lenses and concave mirrors is the focal length, f, and is defined as the image distance of an object that is positioned infinitely far way. The focal lengths of a biconvex lens and a concave mirror are shown in Figures 1 and 2, respectively. Notice the incoming light rays from the object are parallel, indicating the object is very far away. The point, C, in Figure 2 marks the center of curvature of the mirror. The distance from C to any point on the mirror is known as the radius of curvature, R.
    [Show full text]
  • 502-13 Magnifiers and Telescopes
    13-1 I and Instrumentation Design Optical OPTI-502 © Copyright 2019 John E. Greivenkamp E. John 2019 © Copyright Section 13 Magnifiers and Telescopes 13-2 I and Instrumentation Design Optical OPTI-502 Visual Magnification Greivenkamp E. John 2019 © Copyright All optical systems that are used with the eye are characterized by a visual magnification or a visual magnifying power. While the details of the definitions of this quantity differ from instrument to instrument and for different applications, the underlying principle remains the same: How much bigger does an object appear to be when viewed through the instrument? The size change is measured as the change in angular subtense of the image produced by the instrument compared to the angular subtense of the object. The angular subtense of the object is measured when the object is placed at the optimum viewing condition. 13-3 I and Instrumentation Design Optical OPTI-502 Magnifiers Greivenkamp E. John 2019 © Copyright As an object is brought closer to the eye, the size of the image on the retina increases and the object appears larger. The largest image magnification possible with the unaided eye occurs when the object is placed at the near point of the eye, by convention 250 mm or 10 in from the eye. A magnifier is a single lens that provides an enlarged erect virtual image of a nearby object for visual observation. The object must be placed inside the front focal point of the magnifier. f h uM h F z z s The magnifying power MP is defined as (stop at the eye): Angular size of the image (with lens) MP Angular size of the object at the near point uM MP d NP 250 mm uU 13-4 I and Instrumentation Design Optical OPTI-502 Magnifiers – Magnifying Power Greivenkamp E.
    [Show full text]
  • The Reflecting Telescope
    The Reflecting Telescope Lens telescopes exist since 1609 when the Dutch maker of The optical properties data of the AstroMedia* reflecting tel- spectacles, Jan Lippershey, sold the first telescopes, then as escope roughly correspond to those of the first instrument a curiosity, to his astonished customers. It was made out of a built by Newton. The mirror has a focal length f=450mm (”f” concave and a convex lens, produced an upright standing from the Latin ”focus” is the abbreviation of focal length). It’s image and had a 3 1/2 times magnification. Galileo Galilei curve is spherical, i.e. is has the same round surface as a (1564-1642) improved on this invention and was the first to globe. make astronomical observations with it. Today almost A spherical concave mirror has one disadvantage: the all lens telescopes are built according to the prin- light rays reflected from the edge meet a little nearer ciples of Johannes Kepler (1571-1630). His tel- to the mirror than those reflected from the centre, escope, based on two convex lenses, produced causing a slight focus distortion. However, since an upside down but much bigger and better this distortion is is not grave and such mirrors focused image which of course for observing are relatively easy to grind, they are neverthe- the heavens are the most important factors. less used in smaller telescopes. In telescopes Building larger telescopes however with larger openings and stronger mag- brings two problems with it: Firstly, nification mirrors with parabolic curves in a lens the light rays are broken, are used.
    [Show full text]
  • Telescopes and Binoculars
    Continuing Education Course Approved by the American Board of Opticianry Telescopes and Binoculars National Academy of Opticianry 8401 Corporate Drive #605 Landover, MD 20785 800-229-4828 phone 301-577-3880 fax www.nao.org Copyright© 2015 by the National Academy of Opticianry. All rights reserved. No part of this text may be reproduced without permission in writing from the publisher. 2 National Academy of Opticianry PREFACE: This continuing education course was prepared under the auspices of the National Academy of Opticianry and is designed to be convenient, cost effective and practical for the Optician. The skills and knowledge required to practice the profession of Opticianry will continue to change in the future as advances in technology are applied to the eye care specialty. Higher rates of obsolescence will result in an increased tempo of change as well as knowledge to meet these changes. The National Academy of Opticianry recognizes the need to provide a Continuing Education Program for all Opticians. This course has been developed as a part of the overall program to enable Opticians to develop and improve their technical knowledge and skills in their chosen profession. The National Academy of Opticianry INSTRUCTIONS: Read and study the material. After you feel that you understand the material thoroughly take the test following the instructions given at the beginning of the test. Upon completion of the test, mail the answer sheet to the National Academy of Opticianry, 8401 Corporate Drive, Suite 605, Landover, Maryland 20785 or fax it to 301-577-3880. Be sure you complete the evaluation form on the answer sheet.
    [Show full text]
  • How Does the Light Adjustable Lens Work? What Should I Expect in The
    How does the Light Adjustable Lens work? The unique feature of the Light Adjustable Lens is that the shape and focusing characteristics can be changed after implantation in the eye using an office-based UV light source called a Light Delivery Device or LDD. The Light Adjustable Lens itself has special particles (called macromers), which are distributed throughout the lens. When ultraviolet (UV) light from the LDD is directed to a specific area of the lens, the particles in the path of the light connect with other particles (forming polymers). The remaining unconnected particles then move to the exposed area. This movement causes a highly predictable change in the curvature of the lens. The new shape of the lens will match the prescription you selected during your eye exam. What should I expect in the period after cataract surgery? Please follow all instructions provided to you by your eye doctor and staff, including wearing of the UV-blocking glasses that will be provided to you. As with any cataract surgery, your vision may not be perfect after surgery. While your eye doctor selected the lens he or she anticipated would give you the best possible vision, it was only an estimate. Fortunately, you have selected the Light Adjustable Lens! In the next weeks, you and your eye doctor will work together to optimize your vision. Please make sure to pay close attention to your vision and be prepared to discuss preferences with your eye doctor. Why do I have to wear UV-blocking glasses? The UV-blocking glasses you are provided with protect the Light Adjustable Lens from UV light sources other than the LDD that your doctor will use to optimize your vision.
    [Show full text]
  • Find Your Telescope. Your Find Find Yourself
    FIND YOUR TELESCOPE. FIND YOURSELF. FIND ® 2008 PRODUCT CATALOG WWW.MEADE.COM TABLE OF CONTENTS TELESCOPE SECTIONS ETX ® Series 2 LightBridge ™ (Truss-Tube Dobsonians) 20 LXD75 ™ Series 30 LX90-ACF ™ Series 50 LX200-ACF ™ Series 62 LX400-ACF ™ Series 78 Max Mount™ 88 Series 5000 ™ ED APO Refractors 100 A and DS-2000 Series 108 EXHIBITS 1 - AutoStar® 13 2 - AutoAlign ™ with SmartFinder™ 15 3 - Optical Systems 45 FIND YOUR TELESCOPE. 4 - Aperture 57 5 - UHTC™ 68 FIND YOURSEL F. 6 - Slew Speed 69 7 - AutoStar® II 86 8 - Oversized Primary Mirrors 87 9 - Advanced Pointing and Tracking 92 10 - Electronic Focus and Collimation 93 ACCESSORIES Imagers (LPI,™ DSI, DSI II) 116 Series 5000 ™ Eyepieces 130 Series 4000 ™ Eyepieces 132 Series 4000 ™ Filters 134 Accessory Kits 136 Imaging Accessories 138 Miscellaneous Accessories 140 Meade Optical Advantage 128 Meade 4M Community 124 Astrophotography Index/Information 145 ©2007 MEADE INSTRUMENTS CORPORATION .01 RECRUIT .02 ENTHUSIAST .03 HOT ShOT .04 FANatIC Starting out right Going big on a budget Budding astrophotographer Going deeper .05 MASTER .06 GURU .07 SPECIALIST .08 ECONOMIST Expert astronomer Dedicated astronomer Wide field views & images On a budget F IND Y OURSEL F F IND YOUR TELESCOPE ® ™ ™ .01 ETX .02 LIGHTBRIDGE™ .03 LXD75 .04 LX90-ACF PG. 2-19 PG. 20-29 PG.30-43 PG. 50-61 ™ ™ ™ .05 LX200-ACF .06 LX400-ACF .07 SERIES 5000™ ED APO .08 A/DS-2000 SERIES PG. 78-99 PG. 100-105 PG. 108-115 PG. 62-76 F IND Y OURSEL F Astronomy is for everyone. That’s not to say everyone will become a serious comet hunter or astrophotographer.
    [Show full text]
  • Solar System Solar System
    Delta Science Reader SolarSolar SystemSystem Delta Science Readers are nonfiction student books that provide science background and support the experiences of hands-on activities. Every Delta Science Reader has three main sections: Think About . , People in Science, and Did You Know? Be sure to preview the reader Overview Chart on page 4, the reader itself, and the teaching suggestions on the following pages. This information will help you determine how to plan your schedule for reader selections and activity sessions. Reading for information is a key literacy skill. Use the following ideas as appropriate for your teaching style and the needs of your students. The After Reading section includes an assessment and writing links. OVERVIEW Students will: discover facts about the Solar System In the Delta Science Reader Solar System, students take a tour of the Sun and the explore the planets and other objects in the planets. Other space objects such as dwarf Solar System planets, comets, asteroids, and meteoroids discuss the function of a table of contents, are explored. Students read about the headings, and a glossary rotation and revolution of the planets and interpret photographs and graphics to the causes of night and day, seasonal answer questions changes, and the phases of the Moon. The book describes the work of a planetary complete a KWL chart geologist. In addition, students discover organize information in a variety of ways how telescopes work. delta science modules Solar System 119 © Delta Education LLC. All rights reserved.
    [Show full text]
  • First Telescope Purchase
    Recommendation Report: First Telescope Purchase Purchasing a telescope can be very confusing for a person who is new to astronomy. This reports provides a comparison of entry-level telescopes for the amateur astronomer and recommends a specific type of telescope for the typical beginning astronomer. This report will focus on different types of telescopes, and not on specific brands. In addition to comparing several different types of telescopes, this report also compares different telescope mounts. Note: This report was prepared for the Austin Telescope Society, which is a non-profit organization dedicated to the enjoyment of astronomy and the education of the public about astronomy. Many people interested in astronomy waste money on a telescope of poor quality. A telescope in a department store may advertise that it can magnify several hundred times; however, the user is often disappointed when the image is dim, shaky, and hazy. To help avoid this confusion, it is important that the beginning astronomer understand the advantages and disadvantages of various types of telescopes. It is vitally important that the telescope have high quality optics and a sturdy mount. No extra gadgets and frills will help a telescope that has poor optics. Definition of Terms Before the actual comparison report, it is vital that several common terms are defined. The following terms must be understood before proceeding with this comparison: • Alt-azimuth mount. A type of telescope mount that moves in two directions: altitude and azimuth. This is the type of motion best illustrated by a cannon. It can be moved up or down, or rotated left or right.
    [Show full text]
  • Holographic Optics for Thin and Lightweight Virtual Reality
    Holographic Optics for Thin and Lightweight Virtual Reality ANDREW MAIMONE, Facebook Reality Labs JUNREN WANG, Facebook Reality Labs Fig. 1. Left: Photo of full color holographic display in benchtop form factor. Center: Prototype VR display in sunglasses-like form factor with display thickness of 8.9 mm. Driving electronics and light sources are external. Right: Photo of content displayed on prototype in center image. Car scenes by komba/Shutterstock. We present a class of display designs combining holographic optics, direc- small text near the limit of human visual acuity. This use case also tional backlighting, laser illumination, and polarization-based optical folding brings VR out of the home and in to work and public spaces where to achieve thin, lightweight, and high performance near-eye displays for socially acceptable sunglasses and eyeglasses form factors prevail. virtual reality. Several design alternatives are proposed, compared, and ex- VR has made good progress in the past few years, and entirely perimentally validated as prototypes. Using only thin, flat films as optical self-contained head-worn systems are now commercially available. components, we demonstrate VR displays with thicknesses of less than 9 However, current headsets still have box-like form factors and pro- mm, fields of view of over 90◦ horizontally, and form factors approach- ing sunglasses. In a benchtop form factor, we also demonstrate a full color vide only a fraction of the resolution of the human eye. Emerging display using wavelength-multiplexed holographic lenses that uses laser optical design techniques, such as polarization-based optical folding, illumination to provide a large gamut and highly saturated color.
    [Show full text]
  • Depth of Focus (DOF)
    Erect Image Depth of Focus (DOF) unit: mm Also known as ‘depth of field’, this is the distance (measured in the An image in which the orientations of left, right, top, bottom and direction of the optical axis) between the two planes which define the moving directions are the same as those of a workpiece on the limits of acceptable image sharpness when the microscope is focused workstage. PG on an object. As the numerical aperture (NA) increases, the depth of 46 focus becomes shallower, as shown by the expression below: λ DOF = λ = 0.55µm is often used as the reference wavelength 2·(NA)2 Field number (FN), real field of view, and monitor display magnification unit: mm Example: For an M Plan Apo 100X lens (NA = 0.7) The depth of focus of this objective is The observation range of the sample surface is determined by the diameter of the eyepiece’s field stop. The value of this diameter in 0.55µm = 0.6µm 2 x 0.72 millimeters is called the field number (FN). In contrast, the real field of view is the range on the workpiece surface when actually magnified and observed with the objective lens. Bright-field Illumination and Dark-field Illumination The real field of view can be calculated with the following formula: In brightfield illumination a full cone of light is focused by the objective on the specimen surface. This is the normal mode of viewing with an (1) The range of the workpiece that can be observed with the optical microscope. With darkfield illumination, the inner area of the microscope (diameter) light cone is blocked so that the surface is only illuminated by light FN of eyepiece Real field of view = from an oblique angle.
    [Show full text]
  • The Microscope Parts And
    The Microscope ­ Parts and Use Name:_______________________ Period:______ Historians credit the invention of the compound microscope to the Dutch spectacle maker, Zacharias Janssen, around the year 1590. The compound microscope uses lenses and light to enlarge the image and is also called an optical or light microscope (vs./ an electron microscope). The simplest optical microscope is the magnifying glass and is good to about ten times (10X) magnification. The compound microscope has two systems of lenses for greater magnification, 1) the ocular, or eyepiece lens that one looks into and 2) the objective lens, or the lens closest to the object. Before purchasing or using a microscope, it is important to know the functions of each part. Eyepiece Lens: the lens at the top that you look through. They are usually 10X or 15X power. Tube: Connects the eyepiece to the objective lenses Arm: Supports the tube and connects it to the base. It is used along with the base to carry the microscope Base: The bottom of the microscope, used for support Illuminator: A steady light source (110 volts) used in place of a mirror. Stage: The flat platform where you place your slides. Stage clips hold the slides in place. Revolving Nosepiece or Turret: This is the part that holds two or more objective lenses and can be rotated to easily change power. Objective Lenses: Usually you will find 3 or 4 objective lenses on a microscope. They almost always consist of 4X, 10X, 40X and 100X powers. When coupled with a 10X (most common) eyepiece lens, we get total magnifications of 40X (4X times 10X), 100X , 400X and 1000X.
    [Show full text]
  • How Do the Lenses in a Microscope Work?
    Student Name: _____________________________ Date: _________________ How do the lenses in a microscope work? Compound Light Microscope: A compound light microscope uses light to ​ ​ transmit an image to your eye. Compound ​ deals with the microscope having more than one lens. Microscope is the ​ ​ combination of two words; "micro" meaning small and "scope" meaning view. Early microscopes, like Leeuwenhoek's, were called simple because they only had one lens. Simple scopes work like magnifying glasses that you have seen and/or used. These early microscopes had limitations to the amount of magnification no matter how they were constructed. The creation of the compound microscope by the Janssens helped to advance the field of microbiology light years ahead of where it had been only just a few years earlier. The Janssens added a second lens to magnify the image of the primary (or first) lens. Simple light microscopes of the past could magnify an object to 266X as in the case of Leeuwenhoek's microscope. Modern compound light microscopes, under optimal conditions, can magnify an object from 1000X to 2000X (times) the specimens original diameter. "The Compound Light Microscope." The Compound Light Microscope. Web. 16 Feb. 2017. ​ ​ http://www.cas.miamioh.edu/mbi-ws/microscopes/compoundscope.html Text is available under the Creative Commons Attribution-NonCommercial 4.0 ​ International (CC BY-NC 4.0) license. - 1 – Student Name: _____________________________ Date: _________________ Now we will describe how a microscope works in somewhat more detail. The first lens of a microscope is the one closest to the object being examined and, for this reason, is called the objective.
    [Show full text]