(Geometrical) Optics …………………………………
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Galileo and the Telescope
Galileo and the Telescope A Discussion of Galileo Galilei and the Beginning of Modern Observational Astronomy ___________________________ Billy Teets, Ph.D. Acting Director and Outreach Astronomer, Vanderbilt University Dyer Observatory Tuesday, October 20, 2020 Image Credit: Giuseppe Bertini General Outline • Telescopes/Galileo’s Telescopes • Observations of the Moon • Observations of Jupiter • Observations of Other Planets • The Milky Way • Sunspots Brief History of the Telescope – Hans Lippershey • Dutch Spectacle Maker • Invention credited to Hans Lippershey (c. 1608 - refracting telescope) • Late 1608 – Dutch gov’t: “ a device by means of which all things at a very great distance can be seen as if they were nearby” • Is said he observed two children playing with lenses • Patent not awarded Image Source: Wikipedia Galileo and the Telescope • Created his own – 3x magnification. • Similar to what was peddled in Europe. • Learned magnification depended on the ratio of lens focal lengths. • Had to learn to grind his own lenses. Image Source: Britannica.com Image Source: Wikipedia Refracting Telescopes Bend Light Refracting Telescopes Chromatic Aberration Chromatic aberration limits ability to distinguish details Dealing with Chromatic Aberration - Stop Down Aperture Galileo used cardboard rings to limit aperture – Results were dimmer views but less chromatic aberration Galileo and the Telescope • Created his own (3x, 8-9x, 20x, etc.) • Noted by many for its military advantages August 1609 Galileo and the Telescope • First observed the -
Corrugated Feed-Horn Arrays for Future CMB Polarization Experiments Settore Scientifico Disciplinare FIS/01
UNIVERSITA` DEGLI STUDI DI MILANO FACOLTA` DI SCIENZE MATEMATICHE, FISICHE E NATURALI DOTTORATO DI RICERCA IN FISICA, ASTROFISICA E FISICA APPLICATA Corrugated feed-horn arrays for future CMB polarization experiments Settore Scientifico disciplinare FIS/01 Coordinatore: Prof. Marco BERSANELLI Tutore: Prof. Marco BERSANELLI Co-Tutore: Dott. Fabrizio VILLA Tesi di dottorato di: Francesco DEL TORTO Ciclo XXIV Anno Accademico 2011-2012 To my parents Introduction The actual most corroborated model of modern cosmology is the “Hot Big Bang Model”, that results in agree with the cosmological scientific discov- eries of the last 50 years. The main observational pillars that support the model are: the discovery by Edwin Hubble of the expansion of the Universe, the abundances of the primordial elements and the discovery of the Cosmic Microwave Background (CMB) radiation. In 1929 Edwin Hubble discovered the linear relationship in distant galax- ies between their distance and recession velocity: v = Hd. The current value for the Hubble constant is known with very high precision as 72 8 Km/sec/Mpc [1], from the measurements obtained by the Hubble Space Tele-± scope on even far distant galaxies w.r.t. to the Hubble measurements. According to the Hot Big Bang Model, in the first era of its life, the Universe was constituted by photons, electrons and protons. During this time the firsts primordial elements were produced, i.e. Helium, Deuterium, and Beryllium. The abundances of the primordial elements can be calculated with precision by the Hot Big Bang Model, resulting in good agreement with the measured abundances [2], [3]. In 1965 Arno Penzias and Robert Wilson discovered the CMB, already predicted in 1948 by George Gamow in the framework of an Hot Big Bang Model. -
Compound Light Microscopes Magnification
Compound Light Microscopes • Frequently used tools of biologists. • Magnify organisms too small to be seen with the unaided eye. • To use: – Sandwich specimen between transparent slide and thin, transparent coverslip. – Shine light through specimen into lenses of microscope. • Lens closest to object is objective lens. • Lens closest to your eye is the ocular lens. • The image viewed through a compound light microscope is formed by the projection of light through a mounted specimen on a slide. Eyepiece/ ocular lens Magnification Nosepiece Arm Objectives/ • Magnification - the process of objective lens enlarging something in appearance, not Stage Clips Light intensity knob actual physical size. Stage Coarse DiaphragmDiaphragm Adjustment Fine Adjustment Light Positioning knobs Source Base Always carry a microscope with one hand holding the arm and one hand under the base. What’s my power? Comparing Powers of Magnification To calculate the power of magnification or total magnification, multiply the power of the ocular lens by the We can see better details with higher power of the objective. the powers of magnification, but we cannot see as much of the image. Which of these images would be viewed at a higher power of magnification? 1 Resolution Limit of resolution • Resolution - the shortest distance • As magnifying power increases, we see between two points more detail. on a specimen that • There is a point where we can see no can still be more detail is the limit of resolution. distinguished as – Beyond the limit of resolution, objects get two points. blurry and detail is lost. – Use electron microscopes to reveal detail beyond the limit of resolution of a compound light microscope! Proper handling technique Field of view 1. -
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. -
Progress Toward Corrugated Feed Horn Arrays in Silicon Abstract
Progress Toward Corrugated Feed Horn Arrays in Silicon J. Britton,∗ K. W. Yoon, J. A. Beall, D. Becker, H. M. Cho, G. C. Hilton, M. D. Niemack, and K. D. Irwin Quantum Sensors Group, NIST, Boulder, CO 80305, USA Abstract We are developing monolithic arrays of corrugated feed horns fabricated in silicon for dual-polarization single-mode operation at 90, 145 and 220 GHz. The arrays consist of hundreds of platelet feed horns assembled from gold-coated stacks of micro- machined silicon wafers. As a first step, Au-coated Si waveguides with a circular, corrugated cross section were fabricated; their attenuation was measured to be less than 0.15 dB/cm from 80 to 110 GHz at room temperature. To ease the manufacture of horn arrays, electrolytic deposition of Au on degenerate Si without a metal seed layer was demonstrated. An apparatus for measuring the radiation pattern, optical efficiency, and spectral band-pass of prototype horns is described. Feed horn arrays made of silicon may find use in measurements of the polarization anisotropy of the cosmic microwave background radiation. Imaging detectors at millimeter wavelengths can now be built with hundreds of pixels.[1] However, parallel gains in free-space coupling optics have lagged. At NIST we are pursuing monolithic arrays of corru- gated platelet feed horns made with Si. Each layer in the stack is a Si wafer with photolithographically de- fined apertures. Once assembled and coated with Au, these horn arrays are expected to feature the same low loss, wide bandwidth, minimal side lobes and low cross- correlation as electroformed horns.[2, 3] Moreover, rel- ative to metal corrugated arrays [4], Si horn arrays are expected to have the following benefits: (a) a thermal ex- pansion matched to Si detectors, (b) lower thermal mass, and (c) a straightforward development to arrays of thou- sands of horns. -
Object-Image Real Image Virtual Image
Object-Image • A physical object is usually observed by reflected light that diverges from the object. • An optical system (mirrors or lenses) can 3.1 Images formed by Mirrors and Lenses produce an image of the object by redirecting the light. • Images – Real Image • Image formation by mirrors – Virtual Image • Images formed by lenses Real Image Virtual Image Optical System ing diverging erg converging diverging diverging div Object Object real Image Optical System virtual Image Light appears to come from the virtual image but does not Light passes through the real image pass through the virtual image Film at the position of the real image is exposed. Film at the position of the virtual image is not exposed. Each point on the image can be determined Image formed by a plane mirror. by tracing 2 rays from the object. B p q B’ Object Image The virtual image is formed directly behind the object image mirror. Light does not A pass through A’ the image mirror A virtual image is formed by a plane mirror at a distance q behind the mirror. q = -p 1 Parabolic Mirrors Parabolic Reflector Optic Axis Parallel rays reflected by a parabolic mirror are focused at a point, called the Parabolic mirrors can be used to focus incoming parallel rays to a small area Focal Point located on the optic axis. or to direct rays diverging from a small area into parallel rays. Spherical mirrors Parallel beams focus at the focal point of a Concave Mirror. •Spherical mirrors are much easier to fabricate than parabolic mirrors • A spherical mirror is an approximation of a parabolic Focal point mirror for small curvatures. -
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. -
Lab 11: the Compound Microscope
OPTI 202L - Geometrical and Instrumental Optics Lab 9-1 LAB 9: THE COMPOUND MICROSCOPE The microscope is a widely used optical instrument. In its simplest form, it consists of two lenses Fig. 9.1. An objective forms a real inverted image of an object, which is a finite distance in front of the lens. This image in turn becomes the object for the ocular, or eyepiece. The eyepiece forms the final image which is virtual, and magnified. The overall magnification is the product of the individual magnifications of the objective and the eyepiece. Figure 9.1. Images in a compound microscope. To illustrate the concept, use a 38 mm focal length lens (KPX079) as the objective, and a 50 mm focal length lens (KBX052) as the eyepiece. Set them up on the optical rail and adjust them until you see an inverted and magnified image of an illuminated object. Note the intermediate real image by inserting a piece of paper between the lenses. Q1 ● Can you demonstrate the final image by holding a piece of paper behind the eyepiece? Why or why not? The eyepiece functions as a magnifying glass, or simple magnifier. In effect, your eye looks into the eyepiece, and in turn the eyepiece looks into the optical system--be it a compound microscope, a spotting scope, telescope, or binocular. In all cases, the eyepiece doesn't view an actual object, but rather some intermediate image formed by the "front" part of the optical system. With telescopes, this intermediate image may be real or virtual. With the compound microscope, this intermediate image is real, formed by the objective lens. -
Resolving Interference Issues at Satellite Ground Stations
Application Note Resolving Interference Issues at Satellite Ground Stations Introduction RF interference represents the single largest impact to robust satellite operation performance. Interference issues result in significant costs for the satellite operator due to loss of income when the signal is interrupted. Additional costs are also encountered to debug and fix communications problems. These issues also exert a price in terms of reputation for the satellite operator. According to an earlier survey by the Satellite Interference Reduction Group (SIRG), 93% of satellite operator respondents suffer from satellite interference at least once a year. More than half experience interference at least once per month, while 17% see interference continuously in their day-to-day operations. Over 500 satellite operators responded to this survey. Satellite Communications Overview Satellite earth stations form the ground segment of satellite communications. They contain one or more satellite antennas tuned to various frequency bands. Satellites are used for telephony, data, backhaul, broadcast, community antenna television (CATV), internet, and other services. Depending on the application, each satellite system may be receive only or constructed for both transmit and receive operations. A typical earth station is shown in figure 1. Figure 1. Satellite Earth Station Each satellite antenna system is composed of the antenna itself (parabola dish) along with various RF components for signal processing. The RF components comprise the satellite feed system. The feed system receives/transmits the signal from the dish to a horn antenna located on the feed network. The location of the receiver feed system can be seen in figure 2. The satellite signal is reflected from the parabolic surface and concentrated at the focus position. -
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. -
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. -
Development of Conical Horn Feed for Reflector Antenna
International Journal of Engineering and Technology Vol. 1, No. 1, April, 2009 1793-8236 Development of Conical Horn Feed For Reflector Antenna Jagdish. M. Rathod, Member, IACSIT and Y.P.Kosta, Senior Member IEEE waveguide that provides the impedance transformation Abstract—We have designed a antenna feed with prime between the waveguide impedance and the free-space concerned that with the growing conjunctions in the mobile impedance. Horn radiators are used both as antennas in their networks, the parabolic antenna are evolving as an useful device own right, and as illuminators for reflector antennas. Horn for point to point communications where the need for high antennas are not a perfect match to the waveguide, although directivity and high power density is at the prime importance. With these needs we have designed the unusual type of feed standing wave ratios of 1.5:1 or less are achievable. The gain antenna for parabolic dish that is used for both reception and of a horn radiator is proportional to the area A of the flared transmission purpose. This different frequency band open flange), and inversely proportional to the square of the performance having horn feed, works for the parabolic wavelength [8].Following Fig.1 gives types of Horn reflector antenna. We have worked on frequency band between radiators. 4.8 GHz to 5.9 GHz for horn type of feed. Here function of the horn is to produce uniform phase front with a larger aperture than that of the waveguide and hence greater directivity. Parabolic dish antenna is the most commonly and widely used antenna in communication field mainly in satellite and radar communication.