Optics For Kids - The Optical Society: Exploring the Science of Light Other Resources What is Optics? You rely on optics every day. Your digital camera, wireless mouse, and even your Blu-ray disc of your favorite movie are all technologies enabled by the science of optics. Optics is the science of light. More specifically, optics is a branch of physics describing how light behaves and interacts with matter. OK, that sounds like something your 5th period teacher rambles on about, - right? Think of it this way…The power and special properties of light can be used to explore the universe, monitor the environment, and even solve crimes. By utilizing their knowledge of how light behaves under different conditions, scientists and engineers create wicked cool technologies that make your world better. Start your exploration of the science of light by checking out some of the topics below! So whether you’re looking for fun experiments, easy activities, cool projects, interesting facts, or other resources related to optics, you’ll find it all here at Optics4Kids. Optics dictionary definition | optics defined » more... Schuster, Theory of Optics, § 178).

His work was mainly concerned with electricity and magnetism, though he also made some contributions to optics and physiology. Devoting himself next to optics, he produced memoirs which entitle him to a high place among the early, searchers after a true dynamical theory of light. He also carried out many experiments in magneto-optics, and succeeded in showing, what Faraday had failed to detect, the rotation under the influence of magnetic force of the plane of polarization in certain gases and vapours. 11 Astronomical inquiries in connexion with optics, meteorological phenomena, and, in a word, the whole field of natural laws, excited his desire to explain them. Related Optics - NEXT.cc Optics Gallery Optics is the science of seeing. More specifically, optics is a branch of physics that deals specifically with light and vision. We experience the joy of our own optics every day, but how can we see through the eyes of another? What does their world look like? How do our brains know to turn everything right side up? Let’s take a look at how our eyes work by turning a room into a camera obscura. Activity 1 – camera obscura Cover a window with garbage bags. Tape the edges.

Next, cut a 3”x3” square in the middle of the garbage bag (make sure that the opening isn’t obstructed). Cut separate 4”x 4” cardboard squares. In each, cut a central hole starting with a ½” hole; the second square should have a 1" square and so on in ½” increments. These are aperture squares. Cover the window opening with the first aperture square. Tape light leaks shut! Let your eyes adjust and look for an image on the opposite wall. Try different aperture squares until you find one that works for your room. Hint: Often the 2” hole will work. materials You have made your very own camera obscura! Activity 2 – terms! Before you start to build your camera obscura, write down these vocabulary words in your journal: aperture - An opening. In the case of a camera, it is the circular opening in a lens that controls depth of field and amount of light let in. A change in one aperture number halves the amount of light let in.

An aperture number is a ratio calculated by taking the diameter of aperture/focal length of lens camera obscura – instrument used in the 1500’s as a drawing aid, involving the image plane and focal plane, that Is the fundamental concept behind the modern camera focal length - a measurement of lenses from the point at which the light enters the lens until it hits the film plane focused at infinity, often calculated in millimeters ISO – the lower the film speed, the finer the grain and less sensitivity to light; the higher the film speed, the more visible the grain and more sensitivity to light shutter speed – the length of time that the shutter mechanism lets light in to expose the film Activity 3 – take a picture! camera that has an"M" or Manual setting tripod shutter Release light Meter film (if applicable) wide-angle lens Place the camera on the tripod. Focus and set your camera to f/16 (aperture #16). Set your meter to the film speed (ISO) by pressing the “ISO” button on the meter and scrolling until they match. Now press the “mode” button until a little sun-shaped symbol appears on the top of the light meter screen. This sets your camera for ambient exposure.

Put your light meter in the light of the projected image and press the button on the side. Two numbers should pop up. One is the shutter speed and the other is the aperture. By scrolling you can change the relationship between the two. Scroll until the aperture is 16. This will give you the proper exposure for f/16, at the given shutter speed and ISO. It will most likely be more than one second. Plug all of these numbers into your camera. If the exposure is more than one second, put your shutter speed setting on “B.” Put on a shutter release cable. Press the button for the time indicated on the meter. Let go. You have made your exposure! Review What is an aperture in a camera? An onboard algorithm A hole that lets light in What is an f-stop? What does shutter speed control? The motion in a picture The amount of light let into a camera All of the above Another name for film speed The opposite of ASA A word for being cold Focal point, film plane, image plane and focal plane are all parts of an image.

true Optics For Dummies:Book Information - For Dummies Optics For Dummies Author Information The easy way to shed light on Optics In general terms, optics is the science of light. More specifically, optics is a branch of physics that describes the behavior and properties of light?including visible, infrared, and ultraviolet?and the interaction of light with matter. Optics For Dummies gives you an approachable introduction to optical science, methods, and applications. You'll get plain-English explanations of the nature of light and optical effects; reflection, refraction, and diffraction; color dispersion; optical devices, industrial, medical, and military applications; as well as laser light fundamentals. Tracks a typical undergraduate optics course Detailed explanations of concepts and summaries of equations Valuable tips for study from college professors If you're taking an optics course for your major in physics or engineering, let Optics For Dummies shed light on the subject and help you succeed! Buy Both and Save 25%! + Science Information | Branches of Physics | Tech Hydra Branches of Physics Home » Science » Physics » Branches of Physics Branches of Physics Graduate school for a physicist proposes additional challenges as budding scientists ponder which branches of physics they wish to pursue for their scientific career.

Physics is a sub branch of science which fundamentally applies to all forms of physical science studies. Physics acts as a root to myriad studies in the scientific community as it is provides the knowledge of how matter and energy work which are essential to the fundamental principles of biology and chemistry. Acoustics The study of acoustics involves sound, ultrasound, infrasound and vibration waves in all 3 physical states of matter: solids, liquids and gases. Acoustical engineers or acousticians are the titles provided to physicists who specialize in this branch of science. Sounds has been an instrumental tool in the development of human evolution and more recently cultural revolutions of humanity. Astronomy Astronomers are fascinated by studying the chemistry, mathematics and physics of celestial bodies as well as events that occur outside Earth’s atmosphere and throughout the universe. Plants, moons, stars, solar systems, galaxies and anomalies such as black holes, super novas, gamma ray bursts and solar radiation are some of the many areas of research explored by this discipline. Astrophysics A subdivision of astronomy, astrophysics is the study of the physics of how objects interact with each other across the universe.

Gravitational force, electromagnetism, particle physics, temperature, density and thermodynamics are all intertwined in how objects behave and interact with each other to allow celestial bodies to form in the complex varieties that exist today. Atomic Physics Atomic physics studies the interaction between electrons and the nucleus of an atom. This differs from nuclear physics which is concerned with only atomic nuclei solely. Atomic models consider atoms in isolation along with how electrons are exchanged with other atoms in proximity. Configuration of the electron shell, binding energy, kinetic energy and ionization are fundamental components of this branch of physics. Biophysics Biological systems are bound by the laws of physics like all matter leading to the necessity for biophysicists. By studying the mathematics of living structures and their DNA and RNA makeup allowed research into bioengineering, biotechnology, nanotechnology and biochemistry. The ability to alter living systems by recoding DNA is already underway in some microorganisms. Chaos Theory Choas theory uses mathematics to investigate the dynamics of systems which are highly vulnerable to the introduction of conditions making outcomes seemingly impossible to predict. Commonly known as “the butterfly effect”, making minor changes in initial values produce dramatically different results which can be imagined in terms of alternate realities and the creation of the universe.

Chemical Physics Chemical physicists use the fundamental understanding of physics to analyze the complexity of chemical processes. The combination of molecular chemistry and quantum mechanics explain how chemical bonds form, how chemical reactions initiate and how nanoparticles behave. This field of science is an intertwined perspective of the elaborate interactions of physics and chemistry. Computational Physics Creation of algorithmic logic as a means of problem solving to support quantitative theory is the basis of computational physics. Prediction of the behavior of systems through mathematics and modeling provides insight into the outcome of phenomena that could otherwise be difficult to observe and record. This is a key tool for many other fields of science to conduct preliminary experiments based on predictive mathematics. Cosmology Cosmology, astrophysics and astronomy are similar fields of study however cosmologists ponder particularly about the origins and the future of the universe. Dealing with the universe as a whole, phenomena such as the Big Bang, dark matter, black holes, wormholes, expansion of the known universe and a potential multiverse are dominant areas of interest in cosmology. Cryophysics (Cryogenics) Also known as low temperature physics and generally pertaining to temperatures below -150°C or -238°F (123 K) and how matter behaves to cold conditions.

Cryogenicists tend to avoid using the standard temperature formats of Celsius and Fahrenheit but instead use Kelvin or Rankine scale which are considered to be an absolute scale. Cryobiology, cryosurgery, cryonics, cryogenics and cryoelectronics are are subspecialties of cryophysics. Crystallography The study of crystallography explores atoms in their solid state of matter with particular focus in molecular and atomic structure. Previously the study of geometry of crystals in relation to their axises was necessary to shed light within this field however in recent years the development of x-ray diffraction allows a much greater insight into the axes and symmetry of crystals. Electromagnetism There are four fundamental forces of nature which determine the interactions between matter and energy which include strong interaction, weak interaction, gravitational force and electromagnetic force. Scientists that specialize in electromagnetism investigate phenomena such as electrically charged particles, magnetic attraction and electromagnetic fields. Electronics Electrical circuits, diodes, transistors, integrated circuits and vacuum tubs are all areas of interested for a scientists who is fascinated by electronics.

The flow of electrons along a predesignated pathway to process information and generate signals in telecommunication have helped advance civilization, culture and knowledge of humanity in the modern era. Fluid Dynamics The mechanics of motion in fluids in both liquid and gaseous states are investigated in studies of fluid dynamics. The subdisciplines of hydrodynamics, relating to liquid in particular, and aerodynamics, its gas equivalent, are also considered to be natural sciences which help understand the interactions between energy and matter on earth and throughout space. Geophysics Studying the Earth’s environment including how interactions such as gravity, magentic fields, volcanism, plate techtonics and hydrological cycles are influenced by each other and by celestial bodies is one of the many areas of expertise of a geophysicist. Observations can be made both in the field of natural sciences as well as by producing computer models to forcast predictions based on computational mathematics. High Energy Physics High energy physics is a branch that deals with the fundamental nature of the universe which utilizes particle physics to explain the origin of rare events and anomalies that can be found in space and throughout the universe.

Phenomena such as solar fusion, black holes and gamma ray bursts are investigated by physicists in this field to determine how interactions between particles can cause the release of high amounts of energy. High Pressure Physics Temperature and pressure often go hand in hand in mathematical calculations and engineering which has led to research in the field of high temperature physics. Scientists investigation the correlation between these forces help to provide models and predictions to answer questions into the nature of how pressure and temperature create energy that is apparent in throughout the known universe. Laser Physics Photons are a type of particle which behave and react differently to friction than many other known particles. Quantum electronics and optics play a vital role in this branch of science. The first known concept of a laser was developed by Albert Einstein based off of observations taken from Max Planck in his writings about the laws of radiation. The popular formula E=MC2 underlines the belief that light speed is the fastest speed known due to the distinct effect of friction on proton particles. Mathematical Physics Mathematics has played an integral role in physics and science since ideas have begun to formulate in the minds of the scientific community.

The use of mathematics in its application for problem solving and trouble shooting has led to the need for specialists pursue this branch of physics in order to prove the possibilities of theoretical philosophies and practical applications. Mechanics Mechanics pertains to the behavior of physical objects as well as how force applies and displaces objects in their environment. Knowledge of energy and friction are of key importance in this discipline which crosses physical science and engineering. The roots of mechanics came from ancient Greece in philosophies projected by Aristotle and Archimedes which were later elaborated on by Galileo and Sir Isaac Newton. Meteorology The origins of meteorology are rooted from ancient India which has evolved into the science of studying the atmosphere. Modern techniques have sprung about in the past three centuries as technology has advanced to give humanity a greater understanding of the dynamics of the Earth’s atmosphere. Gravity, the Earth’s spin, polarity, wind and temperature all play a crucial role in the investigation of physical and chemical phenomenons in the atmosphere. Molecular Physics This discipline shares many aspects with atomic physics and involves the study of molecules, atoms, chemical bonds and molecular dynamics which encompasses a variety of branches of science including physical and theoretical chemistry.

The molecular orbital theory is derived from the atmoic orbital theory used in atomic physics to explain the importance of the electron orbit around a nucleus. Nanotechnology Nanotechnology or nanotech refers to the ability to manipulate properties of matter at the molecular, atomic and subatomic levels. The term nanoparticle is used to classify particle types that are between the size scale of 1 – 100 nanometers. Quantum mechanic theories play an integral role in the investigation of nanotechnology by providing insight into how atomic and subatomic particles interact with each other. Nuclear Physics Nuclear physics uses the applications of the physical characteristics of the atomic nuclei to develop research into nuclear power and weapons technology. This branch of physics however is not limited to what one would imaging simply as nuclear technology but also includes a variety of other areas of exploration into magnetic resonance imaging, material engineering, geology (radio carbon dating) and medicine. Optics Optical sciences is the study of the properties and behavior of light along with the interactions of light, matter and energy. As an electromagnetic wave, light is currently classified by scientists by its wave length frequency in visible, ultraviolet and infrared spectrums.

The discovery that light is essentially electromagnetic radition is a theory that came about in the 19th century and has continued to fascinate physicists since then. Particle Physics Particle physicists have been making great strides in their research with the development of advanced technologies such as the large hadron collider developed by CERN. The ability to analyze detailed information by colliding particles together at high rates of speed has led to the discovery of new types of particles previously theorized by physicists around the world. Research into particle physics has the potential to help scientists better understand the origins of our universe and the complexity of factors that govern the world we know. Plasma Physics Plasma is the fourth state of matter which is characterized by heating gases to the point at which ionization occurs altering the number of electrons in the atoms (releasing electrons from the nucleus). Although we are typically taught that only 3 states of matter exist (solids, liquids and gases) ironically plasma is the fourth and most common state of matter throughout the universe which is most commonly visible in the form of stars. Quantum Electrodynamics Quantum electrodynamics is the study of how matter and light interact with each other and is a merge of the theories of quantum mechanics and special relativity.

This branch of physics sheds light on how matter and light can interact though electrically charged particles share protons during electromagnetic events. Theories in quantum electrodynamics have revolutionized theories developing and evolving throughout physics and other disciplines of sciences. Quantum Mechanics Quantum mechanics is also sometimes referred to as quantum theory which investigates how physics applies at a subatomic and microscopic level. This discipline of science explains how energy and matter behave through the use of mathematical formulas which describe particle and wave behavior. Only through understanding of the behavior of microscopic particles is it possible to gain insight into phenomena which occur on a macroscopic scale. Quantum Optics Quantum optics uses the principles of quantum mechanics to describe how light interacts with other forms of matter in the universe. Quantized photons are studied to observe the behavior of light particles in a vacuum which was first hypothesized by Max Planck in 1899. Einstein elaborated on these theories with his observation of photoelectric effects in his writings in 1905. Quantum Gravity Quantum gravity has remained an elusive and complex mystery to many physicists who seek to unify theories of quantum mechanics and general relativity in a mathematical formula.

Currently quantum gravity is described in the Standard Model and recent evidence through research at the Large Hadron Collider in CERN has helped to shed new light into the Higgs boson particle which reinforces theories previously conceived on the topic. Relativity The theories of special relativity and general relativity first conceived by Albert Einstein encompass the greater theory of relativity in modern physics today. The relationship of velocity, time, space, matter and energy are all explored by physicists in the theory of relativity which is a cross of disciplines in physics and astronomy. Statistical Mechanics Statistical mechanics is the application of mathematical equations to create a model for molecular properties which can be applied to a larger population. Used for examining properties of thermodynamic behavior such as energy, heat, work and entropy the framework of statistical mechanics explains theories on how gases interact with properties of thermodynamics. String Theory String theory was proposed by theoretical physicists and suggests that the particles known in standard particle physics could be one dimensional string like objects. The properties of observed elements are governed by their quantum states. Although proposed “theory of everything”, there exists a few variations of the fundamental principles of string theory which continues to evolve as new physical evidence is discovered to support areas outlined by theoretical physicists.

Thermodynamics Thermodynamics is the study of how heat relates to work and energy. This branch of natural science incorporates principles of chemistry and physics (in addition to statistical mechanics) to explain phenomena such as radiation, temperature, entropy and energy dispersion in both microscopic and macroscopic terms. Four main laws exist in thermodynamics which essentially defines the internal energy of system and how this relates to energy and work in a closed as well as how this translates to temperature and entropy of external systems. Search for: Explaining What We Do: A Gentle Introduction to Optical Design Explaining What We Do: Gentle Introduction to Optical Design and Lens Design By Bruce Irving, Synopsys What is optical design? How does it connect with other areas of optics, optical systems, and optical engineering? How do you do it? These are the subjects of this "gentle introduction." Our hope is to give you a flavor of what is involved, and to point you to other sources in case you want to learn more. Our business is based largely on what is commonly called "lens design" or (more correctly) optical design. This article is for the general reader who may be curious about this area of applied optics. Learning More What Is Optics?

Optics is a branch of physics: the science of light. Optics is concerned with all aspects of the behavior of light and thus covers a lot of territory. Questions that range from " Why is the sky blue? " to " Why does a magnifying glass make things look bigger? " to " How does a laser work? " are all the proper domain of the science of optics. Although we usually think of visible light when we say "optics," visible light is simply a narrow band of the electromagnetic spectrum, which ranges in wavelength from very short (e.g., X-rays) to medium (e.g., green light) to very long. Optics can help us with these other wavelength regions, but most of our discussion here will focus on the important and familiar visible spectrum (i.e., the colors of the rainbow, from violet light with wavelengths near 400 nm [nanometer, one-billionth of a meter] to red light near 700 nm). For comparison, X-ray wavelengths are in the nanometer range, while radio waves range from centimeters to meters in wavelength. One interesting fact about light is that it acts sometimes like a wave, other times more like a stream of very fast particles or quanta called photons.

This wave/particle duality remains one of the mysteries of nature, but in practice we emphasize and use whichever aspect makes our calculations easier! In lasers and detectors, quantum effects are especially important, but in optical design, wave or "physical" optics tends to dominate. Under the right circumstances, we can further simplify our calculations with the additional concept of light rays . Rather than thinking about waves propagating through space, we think about lines that are normal to the waves (i.e., traveling in the direction of the advancing wave front), and we call these lines light rays or simply rays. The behavior of these rays can be modeled by some relatively simple equations (remember Snell's Law ?), and much of optical design is therefore based on rays. This is called geometrical optics (don't worry, we still keep track of quantum and physical optics effects when needed to get the right answers!). Optical Engineers Optical engineers make use of optics to solve problems and to design and build devices that make light do something useful. This requires them to understand and apply the science of optics in substantial detail, in order to know what is physically possible to achieve. But they also must know what is practical in terms of available technology, materials, costs, design methods, etc.

Optical engineers work in all areas of optics, using different techniques to design lasers, build telescopes, create fiber optics communication systems, and much more. As with other fields of engineering, computers are important to many (perhaps most) optical engineers. They are used with instruments, for simulation, in design, and for many other applications. Engineers often use general computer tools such as spreadsheets and programming languages, and they also make frequent use of specialized software designed specifically for their field. Lenses and Lens Designers So what is a lens? You might think this is a simple question -- just a curved piece of clear glass or plastic, right? Well, right -- this is one type of lens, and the most common type at that (most eyeglass and contact lenses are this type). To a lens designer, though, a lens is a more general device, basically any system that tries to collect and distribute light in a specifically desired way. This is closer to what we think of when we discuss interchangeable "lenses" for a 35 mm SLR (single lens reflex) camera (e.g., normal, wide angle, telephoto, zoom).

If you cut one open (don't try this at home, kids!), you'd find that such a camera lens contains a number of single "lenses" of different shapes and sizes. We refer to these as lens elements, and the complete lens is more generally called an optical system. With this terminology, the lens designer today is more often called an optical designer, though the older term is still widely used, along with such whimsical descriptive names as "ray bender." It is increasingly common today for "lens designer" to be but one of a number of titles worn by an optical engineering generalist (who may or may not have a specific optics background -- many people doing lens design today are physicists or other types of engineers by original training). With this background, a lens (or optical system) can actually contain any number and combination of lens elements, mirrors, prisms, rotating polygon scanners, filters, diffraction gratings, holographic elements, and other sorts of optical components. The designer also has to think about what sort of light source will be used with the lens (light bulbs, LEDs, lasers, stars, the sun, etc.).

Also important is the type of "detector" (detectors are devices that react to light, such as film, photodetectors, CCD arrays, or the unsurpassed human eyeball). Systems for infrared (IR) and ultraviolet (UV) light expand the number and types of sources and detectors we consider, but the principles are the same, and lens designers work frequently with IR and UV systems as well as with visible light (special materials are often required for IR/UV work since normal optical glass doesn't work well outside the visible spectrum). So the modern lens designer may work on "lenses" that are a long way from your bifocals or pocket 35 mm camera (although the compact lens in a pocket camera can represent some clever design and cost-effective engineering). If a system uses light in some way (including any system that uses laser beams), lens design is almost certainly involved. Some examples: Microscopes, telescopes, binoculars The Hubble Space Telescope (and its retrofitted repair optics) And many, many more ...

Band structure for a 2D hexagonal lattice of air holes The Hubble Space Telescope is perhaps the most famous space-based optical system, and several engineers at Optical Research Associates (ORA®, now part of Synopsys) actually worked on the design and other aspects of the repair optics (ORA even won a NASA award for this and other space-related work). How to Design a Lens Now that we know what a lens is, how do you design one? The full details are a bit beyond the scope of this "gentle introduction," but we can outline the typical steps. Problem definition - Other engineers or disciplines may define the requirements and boundaries of the design problem, but it is up to the lens designer to translate these into detailed optical specifications such as field of view and focal length. Your performance spec should be here also -- a detailed description of how good an image the lens must form (there are various types of optical evaluation used for this purpose). There may be many requirements to meet, some of them contradictory in terms of how you approach the design (e.g., large aperture and light weight are usually opposing requirements that lead to tradeoffs and compromises). Pre-design - Once the basic factors are set, there are decisions to be made, such as reflecting vs.

refracting? Number of elements? Overall size? Pre-design often involves paper and pencil sketching, including rough graphical ray tracing, with thin lenses standing in for real lenses. There are some graphical software tools that can really help in this stage, especially when pre-design tradeoffs ("what-ifs") are needed, as they often are. Starting point selection - Concept moves toward reality here, often with the help of an existing solution for a similar situation (books, patents, and your own company's previous work are rich sources here). Software comes into play here, since access to a database of existing designs can really speed up the selection process. Graphical and approximate methods can also be used to create a starting point "from scratch," if necessary. Initial analysis - It helps to have a baseline analysis of the starting point so you can gauge improvement versus the spec. Aberration analysis may not be part of the spec, but it will probably be useful in the design process, especially in selecting variables for optimization. Optimization - Once you define a set of variables (parameters such as curvature, thickness, index of refraction, etc.

that the program can change to try to improve performance), an error function (measure of optical quality, zero typically implying "perfection"), and constraints (boundary values that restrict possible configurations), you are ready to optimize the lens. Numerical methods are used to alter the variables in systematic ways that attempt to minimize the error function while honoring all constraints. Sometimes it goes smoothly, more often it doesn't, so changes are necessary, injecting designer guidance to resolve conflicts (though some software is pretty smart about many types of optimization problems, no program is yet fully automatic, if only because some requirements and esthetic judgments may remain in the designer's head and not in the error function). Final analysis - After optimizing the lens, you need to see if it is actually doing what the original spec says it should do (optimization error functions may not correlate perfectly with specifications such as MTF or encircled energy). If it's not quite there, you may have to go back for some more optimization (perhaps adding variables or changing constraints). You may even have to find a different starting point in some cases. Prepare for Fabrication - If the lens design meets its requirements, you will still have more work to do to prepare for fabrication.

See "The Rest of the Story" (below) for a bit more on this subject. What does this leave out? A lot of the "hard parts" of the design process, in fact. Incomplete or changing specifications. Conflicting requirements. Dead-end solution attempts. Unrealistic schedules. Computer crashes. Nobody said it was easy! Beating the Bad Guys: Aberrations Aberrations remained in comfortable obscurity up until the Hubble Space Telescope's (HST) well-known problem. The fabrication defect made spherical aberration temporarily famous (or perhaps infamous?). In geometrical terms, the concept of aberration is pretty simple. Rays from a zero-dimension point object (like a distant star) imaged through a perfect lens will all focus to a single zero-dimension image point (in reality, diffraction effects result in a small but finite size even for aberration-free imaging). If these rays go anywhere else, that is aberration. Aberration can be expressed in various ways, most of which start out by tracing a number of rays through the lens to see where they go.

The ray distribution can be plotted as a scatter plot (we call this a spot diagram), or cross-sections of ray position data can be plotted (ray trace or "rim ray" curves). To those trained in the art, the shapes and sizes of the resulting patterns can tell things about the amount and forms of aberrations that are present, and with this information, you can plan to correct or reduce the aberrations in various ways. Aberration theory breaks down aberration into components (terms of polynomials, actually), and can even assign "blame" for aberration to specific surfaces in the lens (a strongly curved or badly made surface can contribute major amounts of aberration, but surface contribution information at least gives a clue how to proceed). Spherical aberration (SA) is perhaps the simplest to understand, since it depends only on distance from the optical axis. Most optical surfaces are sections of spheres, since these are the easiest surface shapes to make . For a simple spherical-surface lens or mirror, rays at different heights on the surface are not bent to the same degree, so they focus at slightly different distances along the axis; this is SA.

With simple lenses, you can reduce SA by choosing the right lens form (" lens bending ", as we say in the trade). With mirrors (as in the HST), you can correct it by making the mirror a slightly non-spherical conic section (but you have to create the CORRECT conic shape, which was HST's problem -- they built it perfectly against the wrong test standard!). Of course there are OTHER aberrations too, and their interactions may prevent you from making a correction you would like (the old lump-in-the-rug effect -- correct in one place and it pops up in another). This can make lens design a bit challenging (and leads to the next subject of optimization). The Hubble also illustrates the GOOD thing about aberrations: if you know what they are in detail, you can often correct them (especially with a big enough budget!). If the optics are bending the light in the wrong way, elements can be reshaped or other elements added to cancel out the aberration, similar to the way that glasses correct myopic vision (although myopia is not exactly an aberration -- the myopic eye actually has the wrong focal length, so an additional lens is needed to allow it to focus on the retina). How Deep Is My Valley?

(Optimization) Optimization is such an important subject in optical design that we need to say more about it, even though it was briefly described under How to Design a Lens . Remember that the goal of optimization is to take a starting lens of some sort and change it to improve its performance (the starting lens should have a suitable number of optical surfaces of suitable types, since optimization can change only the values of the parameters, not the number or types of surfaces). Since optics is very precise (distances of micrometers can make a big difference), we need to closely determine the values of all our variables at each step of the optimization. Let's consider local optimization first. What does "local" mean? If you have a lens model, an error function is something that correlates with its image performance, like spot size or RMS wavefront error -- smaller is better. As variables are changed, the lens changes, ray trace values change, and the error function takes on new values. If you could plot these out, you would create a map of the hills and valleys of error function space (in anywhere from one to 99 dimensions or more, depending on your variables).

In the admittedly silly sketch above, vertical distance represents the error function value (lower is better), and horizontal position represents ONE of the variables in the lens (for example, it could be the curvature of the front surface). Since smaller is better, your goal is to find the lowest possible point on this map -- the Death Valley of Error Function Land (EFL). Local optimization finds the lowest near-by region in the EFL, so if you are lucky (or smart) in choosing your starting point, you will do well (by analogy, starting in Los Angeles might let you reach Death Valley using local optimization, but starting in New York would not -- you'd probably end up somewhere in New Jersey). Does this analogy help? Maybe not, but the point is, with local optimization, your choice of starting point is very important. (In our picture, local optimization will NOT get you to the lowest point -- it will roll you into one of the valleys to the right or left of the "You are here" starting point). Now consider global optimization. This is an algorithm that somehow looks at the entire map of Error Function Land and (eventually) locates the lowest point regardless of where you started.

Even if you start in Florida, global optimization will eventually get you to Death Valley, though depending on the methods used, it might take a really long time to actually get there, and you might be told about a lot of other low places along the way, some of which might be low enough for your purposes. Silly analogy? Maybe, but the point to remember here is that global optimization considers the whole of "error function space," so your actual starting point is much less critical. (In our picture, global optimization should take you to the desired low point). The Rest of the Story This would not be such a gentle (nor brief) introduction if we actually told you the rest of the story here. There is necessarily much we have left out: Illumination analysis Analysis of manufacturing error effects (this is called tolerancing) Environmental effects (especially thermal) Mounts and baffles Stray light Software can help with almost all of these problems, although the designer remains essential in identifying problems and priorities. Even with all of this, it is still a challenge to turn it all to practice and produce lenses that meet all the requirements in actual use. But you'll have to read elsewhere for the rest of THAT story.

Learning More There are some excellent sources of information about optics, most of them on paper in books and periodicals. This list is just a starting point -- we will add to it over time and we welcome suggestions. In particular, if you know of educational optics resources on the Net, please let us know (send e-mail to optics@synopsys.com ). Basics Molecular Expressions' "Optical Microscopy Primer" on Light and Color This site contains a lot of fascinating information on microscopy, from the basic optics of microscopes to advanced applications and sample images. It's worth a look for the excellent explanations, graphics, and some interactive Java tutorials on refraction, reflection, and other optical topics. It includes details on many subjects only briefly mentioned here, including diffraction, polarization, and interference. A fantastic web site! Open this site in a new window. Eyewitness: Light by David Burnie (Dorling Kindersley, 1992) Part of the "Eyewitness Science" Series, nominally for children, beautifully illustrated with excellent explanations. Optics by E. Hecht and A. Zajac (Addison-Wesley, 1974) A good text at the undergraduate physics level.

Optical Engineering and Design Lens Design Fundamentals by Rudolf Kingslake (Academic Press, 1978) Covers fundamentals needed by working designers. Elements of Modern Optical Design by Donald O'Shea (Wiley-Interscience, 1985) Excellent college-level text with good explanations and a practical orientation. Modern Optical Engineering by Warren Smith (Second Edition, McGraw-Hill, 1990) The standard desk reference and learning tool for optical engineering. Periodicals Optics and Photonics News (monthly, by subscription, Optical Society of America , Washington, DC) News and technical articles (the monthly column "Light Touch" covers "everyday optics" for the non-professional). OSA's Optics Discovery Kit is also an excellent learning tool (materials and instructions for a number of simple optics experiments). OSA no longer directly sells the Optics Discovery Kit, but it should be available through Edmund Scientific Company. Click here for a current link to Edmund's product page (opens a new window). If this link fails, try going to Edmund's main page and do a search for "optics discovery kit," or contact Edmund by email . Other Resources ZAP!

(Edmark Thinkin' Science Series) ZAP! is a PC-based educational software product intended for kids 8 to 12 years old. Although aimed atchildren, the program is an inexpensive and useful tool for anyone with an interest in optics and the concepts of optical system design. Its interactive interface is easy to learn and use, and it helps to build an intuitive understanding about how light, sound, and electricity work. It is also a lot of fun! The subtitle of ZAP! is "Save the Show with Sound, Light, and Electricity," and the concept is that you are helping a rock band to fix the sound and light show for their big concert. You do this in three "workshops" where you can use your mouse to play with simulated components of several types. You build simple circuits in the electricity workshop and experiment with sound waves in the sound workshop. In the "laser lab" workshop, you play with light sources, mirrors, lenses, and color filters. By solving simple problems posed by animated characters, or simply by inserting, moving and tilting the parts to design simple optical systems, you can have a lot of fun and learn first-hand about reflection, refraction, color mixing, and more.

When you select and position these optical parts, you are actually designing a simulated optical system. There is also an interactive reference section. [1506.05086] Dialogues about geometry and light Authors: David Bermudez , Jonathan Drori , Ulf Leonhardt (Submitted on 14 Jun 2015) Abstract: Throughout human history, people have used sight to learn about the world, but only in relatively recent times the science of light has been developed. Egyptians and Mesopotamians made the first known lenses out of quartz, giving birth to what was later known as optics. On the other hand, geometry is a branch of mathematics that was born from practical studies concerning lengths, areas and volumes in the early cultures, although it was not put into axiomatic form until the 3rd century BC. In this work, we will discuss the connection between these two timeless topics and show some new things in old things". There has been several works in this direction, but taking into account the didactic approach of the Enrico Fermi Summer School, we would like to address the subject and our audience in a new light.

Question: Optics is a branch of physics specifically concerning?
Answer: Light