Scots uses the same basic test geometry as phasemeasuring or fringereflection deflectometry. Therefore, the necessary quantity of captured fringes is very large, especially for the fringe reflection technique frt, since a pair of phases should be unwrapped to get the slopes of two. Phasemeasuring deflectometry pmd has been developed at erlangen to measure spatially resolved slope data of specular surfaces 1, 2 and 3. In this paper, we develop an anglescentroids fitting acf system and the centroid algorithm to calibrate the reverse hartmann test rht with sufficient precision. The investigation was carried out through a modal analysis. Application and development of wavefront sensor technology. Page 1 of 2 interferometer software and hartmann test software posted in atm, optics and diy forum. Journal preproof 3d shape measurement of convex aspheric surface using reverse hartmann test shanshan wang, yinlong hou, dawei li, qiudong zhu pii.
A lowcost, flexible, high dynamic range test for freeform. Fast temporal phase unwrapping method for the fringe. The scots can be better understood as doing a traditional hartmann test with the light going through the system in reverse. Method of alignment using a laser tracker system abstract. Pdf aspheric and freeform surfaces metrology with software.
A computerized reverse hartmann test article pdf available in applied optics 4923. The instantaneous method is based on multiplexing phase shifted fringe patterns with color, and decomposing them in x and y using fourier techniques. Burge1,2 1college of optical sciences, the university of arizona, tucson, arizona 85721, usa. The work focuses on the structural design and performances of a unique optical test system ots used for measuring metrescale optical surfaces. Su p, parks r e, wang l, angel r p and burge j h 2010 software configurable optical test system. A software configurable optical test system scots based on the geometry of the fringe reflection or phase measuring deflectometry method was developed for rapidly, robustly, and accurately. Singleshot deflectometry for dynamic 3d surface profile. Hi, i know atmosfringe, but it is expensive, is there other choice for interferometer software. Software configurable optical test system semantic scholar. A computerized reverse hartmann test peng su, manal a. Aspheric and freeform surfaces metrology with software configurable optical test system. A new test for optical surfaces university of arizona. Aspheric and freeform surfaces metrology with software.
The small imaging lens and the virtual object are at conjugate positions, where the lens is assumed to be working. Hartmann test and b our softwareconfigurable optical test system scots. Measuring aspheric surfaces with reflection deflectometry. Ci provides test benches or stations for electro optical eo systems composed of multiple sensors or channels. Dynamic metrology holds the key to overcoming several challenging limitations of conventional optical metrology, especially with regards to precision freeform optical elements. Dec 01, 2015 software configurable optical test system scots is one of such pmd tests and has been applied for various astronomical optics including 8.
Then, by taking a picture of the test mirror using a camera, we will know the position of the reflected point. Integrated ray tracing simulation of the scots surface. Scots software configurable optical test system is a useful tool that can provide lens manufacturers with the ability to evaluate the net performance of a lens system without the use of complex metrology systems and setups. Electro optical test systems optical test equipment ci. A linear translator 50 controlled by processor 48 provides for relatively moving the test element 42 along a common optical axis 52 of the interferometer 10 and the test element 42. Nonnull full field xray mirror metrology using scots. A software configurable optical test system scots based on. The scots uses the same basic test geometry as the fringe reflection technique or phase measuring deflectometry pmd 2, 3. These benches are built to provide a comprehensive turnkey solution for all the sensors testing needs of the eo system in question. The laptop illuminates the test surface with a light pattern on the lcd screen and uses the reflected im. Software configurable optical test system advanced deflectometry system measuring surface slope with both high precision and large dynamic range. The flat display is set up with its screen near the. Abstract software configurable optical test system scots1, a computerized reverse hartmann test, can rapidly, robustly and quantitatively measure complex 3dimensional specular surfaces, for instance large segmented solar collectors, faceted automotive headlight reflector or other freeform surfaces. Interferometer software and hartmann test software atm.
Accuracies in the range of 100 200 nrad rms have been achieved ref. Pdf measuring aspheric surfaces with reflection deflectometry. Pointcloud noncontact metrology of freeform optical surfaces. Along with experimental data showing the capabilities of the instantaneous. The software configurable optical test system scots is a simple, inexpensive, yet highly flexible optical test that can be configured with software for almost any specular surface or lens system. We propose a new concept of singleshot deflectometry for realtime measurement of threedimensional surface profile using a single composite pattern. Then, as a consequence, the spots are not focused on the measuring plane, as in the original hartmann test.
If the ruling is substituted by a dark screen with a rectangular array of holes, as in fig. In addition to these methods, another technique is the software configurable optical test system scots, which is based on a hartmann test and uses similar geometry principles as the nullscreen. Research on the relationship of the probe system for the swing arm profilometer based on the point source microscope, m. Software configurable optical test system scots is a simp le, lowcost yet highly flexible optical test that can be configured with software for almost any specular freeform surface. It is widely used in adaptive optics, laser beam quality diagnosis, laser atmospheric communication, optical element and optics system detection, quantitative phase microscope, human eye aberration measurement and other fields. In recent years, phase measuring deflectometry pmd, and software configurable optical test system scots,, have been developed to test the optical concave aspheric surfaces. In its simplest configuration, all that is needed to perform the test is a laptop computer with a builtin camera. Mar 01, 2014 read aspheric and freeform surfaces metrology with software configurable optical test system. The deflectometry provides a feasible way for surface testing with a high dynamic range, and the calibration is a key issue in the testing. During a test, an intensity pattern is displayed on the lcd. Point source microscope optical perspectives group. In detail, if the tested mirror is described by equation z wx, y in a global coordinate system, an arbitrary point m on the test sample will have the coordinate mx m, y m, z m.
We have developed a softwareconfigurable optical test system scots that. A computerized reverse hartmann test, abstract a software configurable optical test system scots based on the geometry of the fringe reflection or phase measuring deflectometry method was developed for rapidly, robustly, and accurately measuring large, highly aspherical shapes such as solar collectors and primary mirrors for astronomical telescopes. Scots uses a camera with an external stop to realize a hartmann test in reverse. Dominguez, alejandro maldonado, guillaume butel, yuhao wang, robert e. The model enables predicting the pointcloud surfacemetrology uncertainty maace and guiding the p of any. Dynamic metrology and data processing for precision freeform. With the external camera stop as the reference, a coordinate measuring machine can be used to calibrate the. Figure 1b shows schematically how the surface slope is measured and calculated. Optical perspectives group, llc is an optical engineering consulting firm specializing in the hardware aspects of optics, particularly the fabrication, testing, assembly and. In traditional temporal phase unwrapping tpu algorithms, wrapped phases with different spatial frequencies are obtained from several groups of phase shift fringes to calculate the unwrapped phase. Faststeering secondary mirror fsm will be installed to the giant magellan telescope gmt as a first generation secondary mirror. A camera observes the image of a sinusoidal grating via reflection at the surface under test. And it seems there is a shack hartmann analyser, where can i download it.
A computeraided testing method based on reverse hartmann test, a fringeillumination deflectometry, is proposed for highaccuracy testing of reflective surfaces. Numerical and experimental modal analysis applied to an. A software configurable optical test system scots based on the geometry of the fringe reflection or phase measuring deflectometry method was developed for rapidly, robustly, and accurately measuring large, highly aspherical shapes such as solar collectors and primary mirrors for astronomical telescopes. Tiptilt tests by using eddy current measuring sensors. The ronchi test 14, as the hartmann test, measures the transverse aberrations, but only in one direction, perpendicular to the lines in the ronchi ruling. A lowcost, flexible, high dynamic range test for free. Software configurable optical test system scots1, a computerized reverse hartmann test, can rapidly quantitatively measure highly aspherical shapes such as solar collectors, giant magellan telescope gmt primary segment with accuracy to micron rms or better without complex calibration. Us5416586a method of testing aspherical optical surfaces.
A software configurable optical test system scots based on deflectometry was developed at the university of arizona for rapidly, robustly, and accurately measuring precision aspheric and freeform surfaces. In addition to using phase shifting methods for data collection and reduction, we explore. Demonstrates a method of using a laser tracker, a simple special fixture and a point source microscope psm to create a virtual spherical mounted retroreflector smr for situations where a smr cannot be attached to the surface to be measured. However, commonly used methods do not always ensure rapid and accurate measurement of different types of convex aspheric surfaces because it is difficult to collect. The ccd camera works as the point source and the screen has the function of the detector in a hartmann. Anglescentroids fitting calibration and the centroid. Both modal analysis of the entire ots and transmissibility function related to its use as an optical system are carried out and analysed. Software configurable optical test syst em scots, a computerized. Based on the finely engineered system hardware, a comprehensive system model was developed capable of characterizing the vertical displacement sensitivity and lateral scanning noise. Quantitative deflectometry challenges interferometry.
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