Telescopes: Augmenting the Eye Text, Chapter 4 Thanks to: howstuffworks.com bbc/science.

Slides:



Advertisements
Similar presentations
Optics and Telescopes Chapter Six. Telescopes The fundamental purpose of any telescope is to gather more light than the naked eye can In many cases telescopes.
Advertisements

Refraction of Light Chapter 17. Index of refraction When light travels from one material to another it usually changes direction The bending of light.
Chapter 27 Optical Instruments.
14.
 If an object is beyond 2F, the image from a converging lens will be inverted, real, and smaller, and will always lie somewhere between F and 2F on the.
1 Earth’s Atmosphere & Telescopes Whether light is absorbed by the atmosphere or not depends greatly on its wavelength. Earth’s atmosphere can absorb certain.
Telescopes. Act as “electromagnetic radiation catchers” Capture as much as possible Focus Magnifies images Telescopes that “catch” visible light are called.
Astronomy for beginners Telescopes By Aashman Vyas.
By Kimberley Evans, Huw Wells and Katy Langley. Catadioptrics use a combination of mirrors and lenses to fold the optics and form an image. There are.
Example: A particular nearsighted person is unable to see objects clearly when they are beyond 2.5 m away (the far point of this particular eye). What.
The Origin of Modern Astronomy Chapter 4:. Isaac Newton 1689.
Slide 1 Light and telescopes Just by analyzing the light received from a star, astronomers can retrieve information about a star’s 1.Total energy output.
Reading Unit 28, Unit 29, Unit 30 Will not be covered by the first exam.
Telescopes and Spacecraft Astronomy 311 Professor Lee Carkner Lecture 7.
Optics and Telescopes Chapter Six.
Telescopes. Optical Telescopes Ground based and on satellites Observations are recorded using a camera instead of the human eye most times. – This is.
Chapter 17 Optics 17.1 Reflection and Refraction
Optical Instruments. Power of a lens Optometrists, instead of using focal length, use the reciprocal of the focal length to specify the strength of eyeglasses.
Land Based Telescopes. Telescopes: "light buckets" Primary functions: 1. ___________ from a given region of sky. 2. ______ light. Secondary functions:
Chapter 25 Optical Instruments.
Telescopes How do they work? Chapter History 2. Lenses & Hardware 3. Reflecting Telescopes 4. Refracting Telescopes.
Telescope Notes 1. Objectives To know the general types of telescopes and the advantages and disadvantages of each one. To know the primary parts and.
Visual Angle How large an object appears, and how much detail we can see on it, depends on the size of the image it makes on the retina. This, in turns,
Refraction. Optical Density  Inverse measure of speed of light through transparent medium  Light travels slower in more dense media  Partial reflection.
Telescopes. Act as “electromagnetic radiation catchers” Capture as much as possible Focus Magnifies images Telescopes that “catch” visible light are called.
Dr. Andrew Tomasch 2405 Randall Lab
Optics and Telescopes Lecture 11. Why do we use telescopes? Human eyes are lenses! Human eyes are lenses! Using larger lenses… Using larger lenses… 
Fundamental of Optical Engineering Lecture 3.  Aberration happens when the rays do not converge to a point where it should be. We may distinguish the.
Basic Telescope Design Refractors: Utilizes a lens (or lenses) to produce the refraction of light to focus light from an object. The main lens is called.
OPTICAL TELESCOPES Optical telescopes gather the visible light to observe distant objects. There are Three Basic Types of Optical Telescopes A.Refracting.
Now You See It Marion White and Alex Treser Period 8/9 AP Physics 1.
When light travels from an object to your eye, you see the object. How do you use light to see? 14.1 Mirrors When no light is available to reflect off.
Copyright © 2010 Pearson Education, Inc. Lecture Outline Chapter 27 Physics, 4 th Edition James S. Walker.
Telescopes and Microscopes. Question: When you look through the converging eyepiece of a telescope, you see an enlarged image of a distant object. If.
Property 5: Refraction experiment ? particle (photon)? wave (E&M) ?
Chapter 18.2 Telescopes.
Science 8 – Unit C: Light and Optical Systems Topic 5: Extending Human Vision.
Astronomy Chapter Nineteen: Galaxies and the Universe 19.1 Tools of Astronomers 19.2 Stars 19.3 Galaxies and the Universe.
Eye (Relaxed) Determine the focal length of your eye when looking at an object far away.
EUROPEAN EXTREMELY LARGE TELESCOPE WILL HAVE A 40 METER MIRROR AND WILL GATHER 13 TIMES MORE LIGHT THAT THE BEST CURRENT TELESCOPE – IMAGES WILL BE 16.
The Nature of Light. Light Can Act Like Waves or In 1801 Thomas Young an English scientist did an experiment. –Double slit experiment Passed a beam of.
A Basic Refractor Telescope The size of the telescope is the diameter of the light-collecting lens.
Telescopes Chapter 3. Objectives To know the general types of telescopes and the advantages and disadvantages of each one. To know the primary parts and.
1 Earth’s Atmosphere & Telescopes Whether light is absorbed by the atmosphere or not depends greatly on its wavelength. Earth’s atmosphere can absorb certain.
Telescopes Augmenting the Eye. Telescopes are devices that allow us to see things far away better. The word comes from the Greek: Τελε = Far Σκοπος =
Refraction P 7.2 LIGHT TELESCOPES AND IMAGES. You should understand that the wave speed will change if a wave moves from one medium into another a change.
Telescopes Mr. Hibbetts Special thanks to Dr. Dan Bruton, Astronomy and Physics SFA.
Lecture Outlines Chapter 27 Physics, 3rd Edition James S. Walker
Today Multiple Lenses The Eye Magnifiers & Microscopes
Chapter 19 Section 4 Microscopes For almost 500 years, lenses have been used to observe objects that are too small to be seen with the unaided eye. The.
Unit 3 Telescopes. Optical Telescopes Two basic types – Refractors – Reflectors.
19.3 Optical Instruments
Telescopes How do they work?. 1. History 2. Lenses & Hardware 3. Reflecting Telescopes 4. Refracting Telescopes.
 Imagine a clear evening when a full moon is just starting to rise. Even though the Moon might seem large and close, it is still too far away for you.
Topic: Telescopes PSSA: D/S8.A.2.2. Objective: TLW compare optical and nonoptical telescopes. TLW compare optical and nonoptical telescopes.
Telescopes & Light. History Hans Lippershey Middleburg, Holland –invented the refractor telescope in 1608 Galileo –the first to use a telescope in astronomy.
Adapted from presentation by Chuck Patterson, Cheyenne, WY, HS teacher
Structure and Function
Telescopes.
Telescopes Chapter 3 Objectives To know the general types of telescopes and the advantages and disadvantages of each one. To know the primary parts.
Telescopes and the Electromagnetic Spectrum Section 3
OPTICAL TELESCOPES Optical telescopes gather the visible light to observe distant objects. There are Three Basic Types of Optical Telescopes Refracting.
How do they work? Chapter 5
Cosmic Perspective and Telescopes
Telescopes How do they work?.
Telescopes Chapter 3.
Telescopes How do they work?.
Unit 3 Space Exploration
Telescopes Augmenting the Eye.
Telescopes.
Presentation transcript:

Telescopes: Augmenting the Eye Text, Chapter 4 Thanks to: howstuffworks.com bbc/science

A telescope is a device used to magnify distant objects. Telescopes come in all shapes and sizes, from a little plastic tube you buy at a toy store for $2, to the Hubble Space Telescope, which weighs several tons.

Most of the telescopes you see today come in one of two “flavors”: The refractor telescope, which uses glass lenses. The reflector telescope, which uses mirrors instead of the lenses. Both types accomplish exactly the same thing, but in completely different ways.

This is the simplest telescope design you could have. A big lens gathers the light and directs it to a focal point and a small lens brings the image to your eye.

To understand how telescopes work, let's ask the following question. Why can't you see an object that is far away? The answer to this question is simple: the object does not take up much space on your eye's screen (retina).

If you had a "bigger eye," you could collect more light from the object and create a brighter image, and then you could magnify part of that image so it stretches out over a larger area on your retina.

Two things make this “bigger eye” possible, the objective lens and the eyepiece lens.

The objective lens (in refractors ) or primary mirror (in reflectors ) collects light from a distant object and brings that light, or image, to a point or focus.

An eyepiece lens takes the bright light from the focus of the objective lens or primary mirror and "spreads it out" (magnifies it) to take up a large portion of the retina.

This is the same principle that a magnifying glass (lens) uses; it takes a small image and spreads it out over the retina of your eye so that it looks big.

When you combine the objective lens or primary mirror with the eyepiece, you have a telescope.

A telescope has two general properties: A telescope has two general properties: – how well it can collect the light – how much it can magnify the image A telescope's ability to collect light is directly related to the diameter of the lens or mirror - - the aperture -- that is used to gather light. A telescope's ability to collect light is directly related to the diameter of the lens or mirror - - the aperture -- that is used to gather light.

The telescope's magnification, its ability to enlarge an image, depends on the combination of lenses used. The eyepiece performs the magnification. Since any magnification can be achieved by almost any telescope by using different eyepieces, aperture is a more important feature than magnification niverse/exploration/jodrell_bank_obse rvatory#p009sgwl

Refractor Telescopes Refractors are the type of telescope that most of us are familiar with. They have the following parts: – a long tube, made of metal, plastic, or wood – a glass combination lens at the front end ( objective lens ) – a second glass combination lens ( eyepiece )

The tube holds the lenses in place at the correct distance from one another. The objective lens gathers the light, and bends or refracts it to a focus near the back of the tube. The eyepiece brings the image to your eye, and magnifies the image.

Refractors have good resolution, high enough to see details in planets and binary stars. However, it is difficult to make large objective lenses (greater than 4 inches or 10 centimeters) for refractors. WHY?

Refraction When light moves at an angle from one material into another, its direction of travel will generally bend. This is called “refraction.”

Refraction not only bends light but also generally spreads the light into its component colors, breaking white light into a spectrum. This chromatic aberration becomes more apparent the further way the observed objects are. Also, the larger the lens the greater the potential chromatic aberration.

Reflector Telescopes Isaac Newton developed the reflector telescope about 1680, in response to the chromatic aberration problem that plagued refractors during his time. Isaac Newton developed the reflector telescope about 1680, in response to the chromatic aberration problem that plagued refractors during his time.

Instead of using a lens to gather light, Newton used a curved, metal mirror (primary mirror) to collect the light and reflect it to a focus. Mirrors do not have the chromatic aberration problems that lenses do. (Newton placed the primary mirror in the back of the tube.)

Because the mirror reflected light back into the tube, he had to use a small, flat mirror (secondary mirror) in the focal path of the primary mirror to deflect the image out through the side of the tube, to the eyepiece; otherwise, his head would get in the way of incoming light. Because the mirror reflected light back into the tube, he had to use a small, flat mirror (secondary mirror) in the focal path of the primary mirror to deflect the image out through the side of the tube, to the eyepiece; otherwise, his head would get in the way of incoming light.

The Newtonian reflector was a highly successful design, and remains one of the most popular telescope designs in use today.

Rich-field (or wide-field) reflectors are a type of Newtonian reflector with short focal ratios and low magnification.

They provide bright, panoramic views of comets and deep-sky objects like nebulae, galaxies and star clusters.

Why Reflectors? The reflector is simple and inexpensive to make. Large aperture primary mirrors (greater than 10 inches or 25 centimeters) can be made easily, which means that reflectors have a relatively low cost per unit of aperture. 1.5 Meter Primary Mirror for Kepler Spacecraft

Reflectors have large light gathering capacities, and can produce bright images of faint, deep- sky objects for visual observing as well as astrophotography. Horsehead nebula, 1500 LY from Earth

Disadvantages of Reflectors You occasionally have to clean and align the mirrors. Slight errors in grinding the mirrors can also distort the image.

More common errors… Spherical aberration Spherical aberration - light reflected from the mirror's edge gets focused to a slightly different point than light reflected from the center.

Astigmatism- the mirror is not ground symmetrically about its center (it might be slightly egg-shaped, for example); star images focus to crosses rather than to points.

Coma Coma - stars near the edge of the field look elongated, like comets, while those in the center are sharp points of light.

Telescopes are devices that allow us to see things far away better. The word comes from the Greek: Τελε = Far Σκοπος = Seer Or Τελεσκοπος “Farseer” All telescopes gather E-M waves (light) and focus it. Some even let you ‘see’ wavelengths you can’t normally see. For example Radio telescopes lets us ‘see’ radio and microwaves.

The Parts of an Optical Telescope An optical telescope gathers visible light to create an image. All have the following parts: An “Objective” lens or mirror that gathers light and creates a real image of the object. Light passes through it or reflects off it first. An “Eyepiece”, a converging lens that makes a magnified virtual image of the real image made by the objective It is this virtual image that you see.

Two types of Optical Telescopes Refracting Telescopes or “Refractor” Which gathers light using a Converging Lens as an Objective Reflecting Telescopes or “Reflector” Which gathers light using a Concave Mirror as an Objective