An analysis of the errors produced by emulsion movement, incorrect hologram size and position, and distortion in hologram plotter and photoreduction lens is given, and it is shown that all the errors are proportional to the slope of the aspheric wavefront. Testing of aspheric surfaces with computer generated holograms. It offers the advantage of an extremely high data density and parallel processing it displays a volume of data instead. This tech nique, however, raises the question of the accuracy of the master surface and also how its shape was established. Softwarebased algorithms run on cpus to efficiently minimize the. The abovementioned software testing types are just a part of testing. Computer generated hologram cgh 1 includes a unique capability for recording and reconstructing the desirable amplitude and phase of object light, leading to a wide use of this technique in optical applications such as threedimensional 3d displays 2, projections 3. Osa computer generated holography using a graphics. More than 40 million people use github to discover, fork, and contribute to over 100 million projects. This tiff file then will be printed on film at high resolution. True holography is changing how we interact with the world. Please note this list is tentative and may change at any time. Computer generated holograms can be used to make reference wavefronts that would be very difficult and expensive to make by other methods. Computer generated holography is a powerful technology suitable for a wide range of display types, including 2d, stereoscopic, autoster eoscopic, volumetric, and true 3d imaging.
This technique permits the null testing of optical components for which there is no possibility of arranging a matching reference surface. Then the use of more sophisticated devices capable of recording computer generated grey scale images was suggested for recording computer generated holograms and computer generated holograms that can reconstruction good quality grey scale images were produced 3,4. So i have covered some common types of software testing which are mostly used in the testing life cycle. The viewing window of a hologram can also be broken up to record many different perspectives, this process is know as spatial multiplexing, and can be used to capture animation andor create a holographic scene from a sequence of 2d images. There is a section entitled digital holography, parts of which appear to be discussing the same topic as this, and parts of which are discussing digital analysis of holograms. Digital holography optically generates a hologram, which is then recorded on a ccd camera, and an image is reconstructed using digital techniques. Computer generated holography using parallel commodity graphics. May be taken for credit six times provided each course is a different topic. Techniques and applications iii, 5 2 parameter e is a small delay in the positions of the sampling pulses with f respect to the origin of the function fx. A hologram is an interference recording of a 3d surface. Design, fabrication and characterization of computer. In computer science field, a computer generated holographic image is computed by.
In this paper, we present the design, fabrication and optical characterization of computer generated holograms cgh encoding information for light beams carrying orbital angular momentum oam. Holograms synthesized by computer are used for constructing optical wavefronts from numerically specified objects. The looking glass works by projecting 45 views of an image, simultaneously, creating the. Algorithms take the target 3d intensity as input and compute the hologram that generates it. The application of computergenerated holograms to testing. We created a series of test images, that are uncompressed tiff. A onedimensional aperture oriented parallel to the image screen general concept consider the amplitude and phase of light that is incident at a location y1 on an image screen that is.
A cgh can be imprinted on a storage media, and the volumetric data can later be retrieved and processed. Computer generated holography achieves patterned illumination at the sample plane through phase modulation of the laser beam at the objective back aperture. However, arbitrary patterns are generally infeasible, so solutions are approximate and often suboptimal. Pdf an overview of recent results in fabrication and application of new types of high precision cghs for interferometric aspherical testing is presented.
Imagine seeing your 3d images in true holographic 3d. An example for testing a steep aspheric surface will be. Ece course syllabus school of electrical and computer. A list of lectures and labs scheduled for this workshop are below. Pdf computergenerated holography as a generic display. Computergenerated holography wikimili, the free encyclopedia. The holographic interface is a computer assisted learning that can be used in. Computer generated holography for computer graphics p. Holography is a technique whereby one wavefront can be recorded and subsequently reconstructed without the presence of the original wavefront. Digital computer generated holography, as mentioned above, provides a static 3d holographic image from 3d volumetric data while obviating the need for specialized photographic equipment, film development and dedicated light sources.
Applications of computer generated holograms for interferometric measurement of large aspheric optics j. When reconstructing the original wavefront from the recording, a three dimensional image is observed. This allows software routines, so called shaders, to be down loaded to. Osa digital holography and threedimensional imaging 2019. Computer generated holography with intensitygraded patterns.
This is especially the case when characterizing large convex telescope mirrors. Computer generated holography is a method of using numerical methods to simulate the physical processes underlying a real hologram s optical recording and reconstruction i. Printing the hologram getting the output from the computer program to a transparency which will diffract light is a particularly crucial step in making computer generated holograms. The corticalcafe computer generated hologram cgh construction kit. Computer generated holography at the university of west bohemia. It is possible for a computer software to calculate the phase of light of an object. This chapter describes the techniques and applications of computer generated holograms. The looking glass works by projecting 45 views of an image, simultaneously, creating the illusion that youre looking at a 3d object. I fx is a bandlimited function, it can be recovered from f s x by passing f, x through a low pass filter. We provide consulting services and hardware for your optical metrology challenges. Hologram imaging technology features, advantages and.
The cgh are drawn directly on electronresist using an electron beam pattern generator which is intended for use in the production of integrated circuits with submicron feature sizes. The course is geared towards scientists, engineers, managers, and researchers interested in exploring fundamentals of computer generated holography, diffractive optical elements, lcos arrays and maskless grayscale lithography who want to. At that time, i was visiting professor toyohiko yatagai1 in japan. The computer generated holograms are designed by the interference of a target wave with a reference wave, which could be, e. One layout of the cghcavity glancing incidence interferometer is studied and factors relating to its first order design are analyzed. The making of a computergenerated hologram features. Diffraction grating multiple if diffraction grating is selected, this is. With luminit threedimensional computer generated holography, a predetermined image e. There are several different types of holograms we can create from computer data. Computer generated holography, software, education. The application of holography in security aspects are discussed in the papers 8, 9, 10 and 11. A computer generated hologram cgh is the core component for an aspheric surface test. Interferometric optical testing using computergenerated holograms cghs has. Lobaz 3dtv conference 2011 320 let us look at the situation when there are two light sources of the same amplitude a.
This is obtained by using liquid crystalbased spatial light modulators lcslms, which modulate the spatial phase of the incident laser beam. Useful to test the resolution of the output device. When sending the hologram to your printer, you want to reproduce it as faithfully as possible. Called computer generated holography, this technology can improve the quality and. Getting the output from the computer program to a transparency which will diffract light is a particularly crucial step in making computer generated holograms. If two light wavefronts are traveling and pass a given point, the. Computer generated hologram cgh eric logean august 2003 abstract this document is an introduction to the design and fabrication of computer generated hologram cgh as i understood them back in 1997. According to fabrication demands, it is necessary to convert the designed cgh phase compensation function into the processed pattern, that is, the fringe discretization process. If a master optical component or optical system is available, a hologram can be made of the wavefront produced by the component or system and this stored wavefront can be used to perform null tests of similar optical systems. The first section gives a basic idea of computer generated holograms.
This osa annual topical meeting covers the areas of interferometry, phase microscopy, novel holographic processes, 3d and novel displays, integral imaging, computer generated holograms, compressive holography, fullfield tomography, and holography with various light sources including coherent to incoherent and xray to terahertz waves. Computer generated holography and diffractive optical. The application of computergenerated holograms to testing optical. An alternative solution to the problem, to be discussed in this paper, uses holography, and in particular computer generated holograms, to generate the required reference wavefront. A glancing incidence interferometric test for large xray mirror mandrels, using two computer generated holograms cgh s, is described. The basic mathematics of computer generated holography are well understood. Luminit computer generated holograms allow viewers to see clear, crisp, and bright holographic images without the need of glasses or other special eyewear. Applications of computergenerated holograms for interferometric. The major difficulties are in two areas computer resources and output media. Holograms are constructed by recording the interference pattern obtained between the wavefields scattered from the object, called object wave, and a coherent reference wave.
Pdf on jan 1, 2004, james h burge and others published use of computer generated holograms for testing aspheric surfaces find, read and cite all the. Arizona optical metrology llc is located in the optics valley tucson, arizona. Holographic studios can transfer your 3d computer generated images into actual three dimensional holography displays. Scientists project holograms into the brain to create. These computergenerated holograms or cghs are mappings of the complex amplitude magnitude and phase of light re. The calculation speed of a gpu geforce 6600, nvidia was found to be about 47 times faster than that of a personal computer with a pentium 4 processor. To drive these, computer generated holograms cghs, rendered from point models are. Algorithmic computer music contains 8 systems of music, 9 chapters with source code fi. Computer generated holography deals with the generation of holograms with the aid of computers. Communications and optical engineering, university of aberdeen, scotland. Holographic foucault null test atm, optics and diy forum. Upon the proper recording, reconstruction, and viewing conditions, unlike the traditional 2d photography, the image appears to be 3d again. We have applied the graphics processing unit gpu to computer generated holograms cgh to overcome the high computational cost of cgh and have compared the speed of a gpu implementation to a standard cpu implementation.
The two cgh s are used to form a double pass glancing incidence system. Because a hologram is simply an interferogram with a large tilt angle between the reference and object wavefronts, holographic tests can be performed either with. In this paper, we propose a new discretization method for a cgh in a test of the freeform surface, and. Dec 21, 2017 in this paper, we present the design, fabrication and optical characterization of computer generated holograms cgh encoding information for light beams carrying orbital angular momentum oam.
Optical testing of aspheric surfaces using computergenerated holograms has been used for many years. Therefore it is important to first understand the principle of superposition and interference of waves. Generate holograms with your pc using this display pcmag. Testing large optical elements can require the use of largesize cghs. The word holography comes from the greek words meaning whole record and is based on the reconstruction of light wavefronts. Optical testing of aspheric surfaces using computergenerated holograms has been. Computer generated fourier holograms for ug laboratory. The two places on campus that can provide us with such equipment are the interactive multimedia lab iml and audio video av. Our main goal is to develop algorithms for generating synthetic holograms of a 3d scene. Pdf use of computer generated holograms for testing aspheric. Enter computer generated holography cgh to create threedimensional floating light shapes.
Jan 22, 2016 computer generated holography computer generated holography cgh is the method of digitally generating holographic interference patterns. Because cghs can control all aspects of the optical wave, threedimensional imagery can be presented to an audience. Hologen suite computer generated hologram software. Elimination of the need for a physical object has made new applications possible, for example, threedimensional computer output. Osa fringe discretization and manufacturing analysis of. There are several different types of holograms we can create from computer. Hardware implementations of computergenerated holography. Special topics in electrical and computer engineering 4 a course to be given at the discretion of the faculty at which general topics of interest in electrical and computer engineering will be presented by visiting or resident faculty members.
Jim burge and chunyu zhao to provide our customers with design and analysis of optical null tests of aspheric surfaces. Computer generated holography at the university of west bohemia who we are. Based on computergenerated holograms cghs, we offer you reference inspection lenses for the field of surface measuring technology. Osa 3d computergenerated holography by nonconvex optimization. Pdf computer generated fourier holograms for ug laboratory. A computer generated hologram will be stored in a tiff format file.
The first step for using digital holograms is the generation process. Computergenerated hologram cgh 1 includes a unique capability for recording and reconstructing the desirable amplitude and phase of object light, leading to a wide use of this technique in optical applications such as threedimensional 3d displays 2, projections 3. This paper discusses recent progress in producing computer generated holograms cgh of low spatial distoration and high spacebandwidth product. Holograms can be entirely computer generated to show the objects or the scenes that never existed, holography are used in many aspects of industrial nondestructive testing, ultrasonic holography, holographic microscopy, holographic memory, holographic film and television.
Computergenerated hologram cavity interferometry test for. The use of computer generated holograms for the testing of aspheric wavefronts is described. The use of computer generated holograms for the testing of aspheric optics, b phaseshifting interferometry for getting interferometric data into a. Holographic interferometry utilizes this property to detected small variations in form, with applications in industrial nondestructive testing. Computergenerated holograms cghs are diffractiveoptical elements that offer the possibility of creating waveoptical display systems that are under complete computer control. Computergenerated phaseonly holograms for realtime. Generate holograms with your pc using this display. The making of a computergenerated hologram features dec. Applications of computergenerated holograms for interferometric measurement of large aspheric optics j. Benefits of computer generated holography for next. Ebeam computer generated holograms for aspheric testing. Traditionally this is a slow process with many different algorithmic approaches used.
To understand the process of image reconstruction by producing simple holograms on a laser printer and reading them out with an optical lens system. I also included in this document a short description of the. Computer generated holography cgh is the method of digitally generating holographic. Computer generated phaseonly holograms for realtime image display 279 4 willbesetbyintech that a pixel is addressed once with a value in the b th bin is pr 1 b. A computer generated hologram is a geometric pattern that can be used as a precise reference in an optical test. A description of the use of the software in digital holography can be found here. The wavefronts that would emerge from the objects are reconstructed by the propagation of light through the hologram. As we increase the angle between the computed reference beam and the computed object beam, the fringe spacing becomes smaller and so the data set becomes very large.
Computergenerated holography cgh is the method of digitally generating holographic interference patterns. Dec 19, 2019 computer generated holography cgh is the method of digitally generating holographic interference patterns. Computer generated holography cgh is the method of digitally generating holographic interference patterns. If computer generated holograms are used to replace the first. Computer generated holography cgh is the method of digitally generating holographic interference patterns matlab holography computer generated holography updated mar 30, 2020. Recently computergenerated holography has been extended in its usage beyond light optics, and applied in generating structured electron wavefunctions with a desired amplitude and phase profile.
The application of computergenerated holograms to the interferometric testing of aspheric reflecting elements and spherical refracting elements has been. As such, it represents substantial progress compared to classical holography. In particular, we offer computer generated holograms cghs for testing aspheric surfaces. Holography is extremely useful for the testing of optical components and systems. Hologram maker vividq secures millions to accelerate growth. The addition of electronics, computers, and software to interferometry has enabled enormous improvements in optical metrology.
Computergenerated holography cgh is a technique to generate holographic. This is because holography records the scene through an area of perspective. Burge steward observatory mirrorlab, university of arizona tucson, arizona 85721 abstract interferometric optical testing using computer generated holograms cghs has proven to give highly accurate measurements of aspheric surfaces. As the holographic recording process is dependant on the interference pattern between opticalwaves the holographic image is the comparative shape between these waves.
Computer generated holograms, synthetic holograms, and computer holograms are terms used to refer to a class of holograms that are produced as graphical output from a digital computer. In particular, we provide the computer generated hologram the key part in the interferometric null test of an. Because cghs can control all aspects of the optical wave, threedimensional imagery can be presented to. Cghs are often used in testing aspheric optics as the null lens or part of the null lens. Clear, crisp, bright image with computer generated hologram cgh. Were especially skilled in holography hoes and pictorial including conventional analog optical and cghdigital, scientific and numerical software, optical analysis and troubleshooting, analog and highspeed digital electronics including algorithm and interface acceleration using. Umutracker we present a versatile and fast matlab program umutracker that automatically detects and tracks pa. I have been reading about holography, and i think i understand the general concept, but one thing that has me completely lost is how computer generated holography works in practice. The application of computer generated holograms to the interferometric testing of aspheric optical elements has been investigated, and it has been shown that they provide a convenient and practical method of producing an aspheric reference wavefront. A computer generated hologram or a cgh is a computed interference pattern of such 3d scene.
A hologram is generally used to modulate the phase or amplitude of a wavefront, causing it to propagate to form a desired phase front or intensity distribution. Research code for performing computational holography and computer generated holography. Computer generated holography utilises the wave theory of light to represent. Testing optical elements by computer generated holograms 1983 interferometry to test further examples of nominally identical components. Vividqs software brings real time computer generated holography cgh to everyday applications.
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