Use of the material Zerodur in the KECK observatory telescope. The very low CTE makes ZERODUR ideal for use as part of the primary mirror. This means that over the temperature range that is possible that the telescope works in, (0-50C), the materi
Introduction The KECK observatory lies near the summit of Mauna Kea in Hawaii. There are two telescopes close to each other on the summit, KECK I and KECK II. These combine to form one of the largest optical telescopes in the world, second only to the Gran Telescopio Canarias (GTC) in the Canary Islands. For good reason, both the KECK observatory and GTC use the same material for their primary mirrors. The primary mirrors of the telescopes are the largest mirrors of the operation, and are designed to gather as much light as possible. The bigger the primary mirror, the more light the telescope can gather, and hence the 'further' into the solar system the telescope can see. With the need to see more and more of space, larger and larger telescopes are being built. However, making a mirror with a diameter of 10 metres of more out of a single sheet of a reflective substance gives a very large problem; the mirror must be very thick in order to hold its shape. When KECK I was being designed, the engineers came up with an ingenious solution, which involved splitting up the mirror into many hexagonal sections, which, when attached together, would act as a single mirror. This meant that the primary mirror would be made from smaller sections, allowing easier maintenance, installation and construction. The mirror is made of 36 hexagonal sections, and forms a slight curve, as shown in
How has the Invention of Contact Lenses affected people's Sight?
Manon Mollard MP5a 14.12.04 Biology: The Impact of Man's Inventiveness on the Human Body. How has the Invention of Contact Lenses affected people's Sight? Introduction People with sight troubles have had the possibility of wearing glasses for a really long time, but the new technology made available contact lenses. In this essay, I am going to look at the different contact lenses types that exist, at who invented them and when, for which vision problems they are solution, at how to take care of them, at how common they are in our society and finally, I will write about my own opinion. What contact lenses are According to the Macmillan Dictionary (2002), contact lens may be defined as "a plastic lens that you wear in your eye to help you see more clearly". A very wide variety of contact lenses are available in today's society, including hard and soft (even if soft is by far more common now), disposable and extended wear; this makes it easy for each person to chose the appropriate type of contact lens for her. The main types of contact lenses are listed below: * Soft lenses: As these lenses are soft, they are made of a large percentage of water, and this allows oxygen to pass through the lens and reach the cornea. They are also more comfortable and easier to adapt to. * Rigid-gas
A brief history of how the light microscope has developed since the 17th Century to the present day.
BIOLOGY A.S. LEVEL INDUCTION TASK: The History, Development and Use of the Light and Electron Microscope A brief history of how the light microscope has developed since the 17th Century to the present day A microscope is "an instrument that enables the human eye, by means of a lens or combinations of lenses, to observe enlarged images of tiny objects. It made visible the fascinating details of worlds within worlds." 1 The earliest simple microscope was a tube with a plate for the object at one end and, at the other, a lens that gave a magnification less than 10 times the actual size. Around 1590 a discovery was made by Zaccharias Janssen and Hans Janssen his son, two Dutch spectacle makers, while they were experimenting with numerous lenses in a tube. They found out that nearby objects were greatly enlarged when looking through the lenses in the tube. Later in 1609 Galileo heard of these experiments and worked on the principles of lenses. After doing so he made an instrument that incorporated a focusing device. Antony van Leeuwenhoek (1632-1723) of Holland was apprenticed in a linen-draper's shop. He set himself up in business as a draper (a fabric merchant) and at some time before 1668, Antony van Leeuwenhoek learned to grind lenses, made simple microscopes, and began observing with them. He taught himself how to polish and grind lenses. Leeuwenhoek's skill at grinding
This essay is on vision, its malfunctions & diagnostics methods.
Vision, its malfunctions & diagnostic methods By Jaswinder Singh .0 Preface This essay is on vision, its malfunctions & diagnostics methods. The content included is concordant with the criteria listed on the specification of the institute of biophysics at 2nd Faculty of Charles University in Prague. Additional acknowledgements are mentioned under the reference section. .1 Visual acuity and its measurement Visual acuity is the measurement of the ability to discriminate two stimuli separated in space at high contrast relative to the background1; it is a quantitative measure of the ability to identify black symbols on a white background at a standardized distance as the size of the symbols is varied. It happens to be the most common clinical measurement of visual function. Visual acuity is typically measured using optotype chart for close and distant vision (snellen test). The eye which is not under test is occluded by means of instructing the subject to place an obstacle, for example a hand in front of the eye. This prevents intentional peeking, which would adversely affect the validity of the examination results. A variety of charts convenient for the patient are used, particularly in cases where a subject is unable to read the alphabet. In such cases the Tumbling E chart may be used, where the perceived letter, capital ''E'' is facing a different direction.
Optical and Electron Microscopy
Biology essay: Optical and Electron Microscopy: Introduction: Microscopes allow us to see things so small they normally can't be seen by the naked eye. The intention of all microscopic studies is to produce an image that is a copy of the object, or the specimen. There are two main aspects to a microscope, which determine the image - magnification and resolution. The magnification is the number of times the image is linearly larger than the object. So, small objects will appear larger in the image under higher magnification than under lower magnification. The resolution, or resolving power, is the microscope's ability to differentiate between small objects that are close together. Theoretically the electron microscope has 100,000 x better resolving power than optical microscopes, but in practise the resolution of an electron microscope is at best 1 nm (nanometre), i.e. two objects less than 1 nm apart will be seen as one. Optical Microscopy: The main instrument, which utilizes light to produce a magnified image, is the compound microscope. A compound microscope uses the magnifying power of two convex lenses, the eyepiece and the objective lens, which itself has three variable magnifying powers - low, medium and high, to produce an image. Light rays are transmitted, the light source usually being a bulb, through the object, and then through the two convex lenses where
Given a Tube Containing a Lens, Calculate The Focal Length of The Lens and Where The Lens Lies Within The Tube.
Given a Tube Containing a Lens, Calculate The Focal Length of The Lens and Where The Lens Lies Within The Tube. Plan I plan to set up the apparatus as shown below and change 'b'. To then make the image focus, I will have to change 'c'. When the image is focused, I will measure 'c' and also the magnification of the image. Using this information I will then be able to calculate 'a'. Hypothesis I predict that using the equations stated in the justification, after measuring values for 'c' and 'm'. I will be able to plot them on the graph of 'c' against 'm' Using the equation c = fm + [f - a]. I believe that if all the equations work, a straight line will be obtained. Safety After considering all aspects of this experiment, I have come to the conclusion that there are no significant safety issues. If normal levels of care are exercised, then there should be no risks involved. Variables that alter * b and c, (from diagram) * Magnification Variables to control * a (from diagram) * Ambient light * Part of object for which magnification is measured each time. * Place b is measured from and to Apparatus list * 0.15m tube * Lens * Object * 12V Power pack * Light source (lamp) white light average wavelength 550Nm * White screen * 2 x 1m rulers (0.0001m increments) * 0.15m ruler (0.0001m increments) * Stand and clamp * Spirit level Method
The history, development and use of the light and electron microscope
The history, development and use of the light and electron microscope History of light microscope Observing objects in detail greater than the naked eye was very interesting to people at early stage. This led to the construction, in the 16th century, of a magnifier composed of a single convex lens, and this, in turn, led to the eventual development of the microscope. The most famous early pioneers in the history of the microscope are Digges of England and Hans and Zcharias Janssen of Holland. But it was Antony van Leeuwenhoek who became the first man to make and use a real microscope. Leeuwenhoek ground and polished a small glass ball into a lens with a magnification of 270X, and used this lens to make the world's first optical microscope. Because it had only one lens, Leeuwenhoek's microscope is now referred to as a single-lens microscope. Its convex glass lens was attached to a metal holder and was focused using screws. The light microscope system was invented in the seventeenth century. This type of microscope incorporates more than one lens so that the image magnified by one lens can be further magnified by another. Today, the term "microscope" is generally used to refer to this type of compound microscope. Since its invention, the light microscope has made tremendous progress and help figure out many biological molecules. Using a light microscope that he had
The use of the electron microscope has advanced our understanding of cell biology further than the light microscope. Discuss." The definition of a microscope is that it is an instrument for viewing objects that are too small
Heather Sanders - Biology Coursework : Ms Belbin "The use of the electron microscope has advanced our understanding of cell biology further than the light microscope. Discuss." The definition of a microscope is that it is an instrument for viewing objects that are too small to be seen easily by the naked eye. Microscopes have been around since the end of the first century and have become an essential instrument within early and modern-day science. Below is a timeline or the innovation of the microscope from when it was first invented, to today. Circa 1000AD The first vision aid was invented (inventor unknown) called a reading stone. It was a glass sphere that magnified when laid on top of reading materials. Circa 1284 Italian, Salvino D'Armate is credited with inventing the first wearable 'eye glasses'. 590 Two Dutch eye glass makers, Zaccharias Janssen and son Hans Janssen experimented with multiple lenses placed in a tube. The Janssens observed that viewed objects in front of the tube appeared greatly enlarged, creating both the forerunner of the compound/light microscope. 665 English physicist, Robert Hooke looked at a sliver of cork through a microscope lens and noticed some "pores" or "cells" in it. 674 Anton van Leeuwenhoek built a simple microscope with only one lens to examine blood, yeast, insects and many other tiny objects. Leeuwenhoek was the first
aspects of physics
Aspects of Physics in the Grove leisure Centre Automatic door system Pool lighting Purpose of each one Automatic door system The purpose is for the doors to open automatically when anyone is a certain distance from the door. The distance should be right for when they are walking up to the door so it has enough time to open when the person is close enough to go through it. The automatic door is needed for disabled access as it is a legal requirement. The grove has had them since the year 2000 because legal reasons state that all public places have to have access for disabled people. It makes it a lot easier for school parties, so the teacher doesn't have to hold the door so they can make sure the children at the front of the queue are looked after and not left unattended. Some people who are medically referred to the leisure centre by their doctors might be very weak and wouldn't be able to open a door, so an automatic door overcomes this problem. Another helpful thing is that the doors will not be left open in winter time, and therefore will not let heat out, which in turn will save money as the building will not need excess heating because heat is being lost. Pool Lighting The lights are not located directly above the swimming pool, the main reason for this is that it would be extremely hard to fix and change them; another reason is that if the lights were directly
Investigating the Positioning of Real Images formed by a Convex Lens.
Investigating the Positioning of Real Images formed by a Convex Lens . Scientific background to the investigation I know that cameras can give us a sharp image, because of rays which start at one particular point go through the optical system at one point. This creates am image on the focal point. I know that every lens has a focal lens. Concave lenses are very similar to concave mirrors, in the way in which they form images, they have the same properties to form images. A concave lens forms an upright, virtual image of any object placed in front of it. The image is always smaller than the object and closer to the lens than the original image. Changing the position of the object changes the position and size of the image which is formed, but the basic form of the diagram stays unchanged. For distant objects, the film must lie at the principal focus of the lens if the image is to be in sharp focus. For closer objects, the distance between the lens and the film must be increased. Accurate focusing of the image is achieved by screwing the lens backwards or forwards in its holder to suit the particular object distance. 2. Secondary sources of information I consulted the text book (Explaining physics) where I was given an equation which was relevant to this investigation. I therefore predict that the investigation data will obey this equation. I will derive the equation