The initial sphere in the fabrication of conic surfaces with small focal ratio (original) (raw)
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Optical traditional interferometers are usually used to evaluate the form of spherical and plane surfaces; those systems could also assess the quality of aspheric surfaces which are quasi-spherical. But if a general aspheric surface is to be evaluated, this procedure requires the purchase of complicated and very expensive devices, such as aspheric interferometer, null-lenses, and computer generated hologram for each aspheric surface. This article presents a solid method allowing the measurement of a wide range of conical aspheric surfaces. This method is based on inserting plane-parallel plate (PPP) within the path of a laser beam coming out of a traditional Fizeau interferometer. This article also presents a mathematical justification that relates the conical surface parameters to the thickness of the inserted PPP. The article also presents the supporting computer simulations and some practical results of applying this method and its range of use.
Off-axis conic surfaces: Interferogram simulation algorithm and its use in stressed mirror polishing
Optics & Laser Technology, 2019
An interferogram simulation algorithm for off-axis conic surfaces is proposed. • The algorithm is used in stressed mirror polishing technique. • The described procedure gives information in real time in a quantitate way. • The procedure helps to control the fabrication process for off-axis optical surfaces. • Irregularity data and aberration coefficients of the surface is obtained.
An assessment of approximating aspheres with more easily manufactured surfaces
Journal of Synchrotron Radiation, 1998
In designing optical systems for synchrotron radiation, one is often led to conclude that optimal performance can be obtained from optical surfaces described by conic sections of revolution, usually paraboloids and ellipsoids. The resulting design can lead to prescriptions for three-dimensional optical surfaces that are difficult to fabricate accurately. Under some circumstances satisfactory system performance can be achieved through the use of more easily manufactured surfaces such as cylinders, cones, bent cones, toroids and elliptical cylinders. These surfaces often have the additional benefits of scalability to large aperture, lower surface roughness and improved surface figure accuracy. In this paper we explore some of the conditions under which these more easily manufactured surfaces can be utilized without sacrificing performance.
Modeling of Surface Generation in Contour Grinding of Optical Molds
CIRP Annals - Manufacturing Technology, 2006
The objective of this paper is the modeling of kinematics of precision contour grinding and resulting workpiece topography. Changes within the contact zone of grinding wheel and workpiece as well as speed ratios are analyzed and evaluated. The generated surface patterns caused by the runout of the grinding wheel are simulated. In the kinematic-geometrical model single grains on the peripheral surface of a grinding wheel, which interact with the workpiece, are considered. After describing the kinematics of the contour grinding process, changes in feed speeds and rotational speed ratios are examined and their effects on generated surfaces are simulated and compared with ground surfaces.
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Pattern Recognition Letters, 1999
Cylindric and conic metallic parts are considered, which are subject to surface treatments (such as, e.g., lathe ®nishing or grinding) that make both Lambertian re¯ection models and purely specular ones inadequate. A new re¯ection model is introduced for such surface treatments, and a method is derived for the determination of the pose and the intrinsic geometric parameter of a cylindric surface or a conic one starting from a single view. This method uses both the projection of the outline of the surface and the re¯ection of known light sources onto it. Ó 0167-8655/99/$ ± see front matter Ó 1999 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 7 -8 6 5 5 ( 9 9 ) 0 0 0 0 5 -7
Assessment of surface geometry using confocal scanning optical microscope
Mechatronics, 1998
Surface geometry and in particular texture and form have played an important role in determining the performance of engineering parts. The present work reports on the development of an optical method based on Confocal Scanning Optical Microscope (CSOM) for measurement and assessment of surface topography and form errors like circularity, cylindricity, sphericity and flatness. The surface topography parameter modifications are studied on workpieces subjected to finishing processes starting from grinding process to various polishing stages. The form error is measured by mounting the specimen on an air bearing rotary stage for accurate measurement. Some new parameters for distinguishing shape from peak to valley error in case of cylindricity measurement are suggested. Some of the 2-D roughness parameters are extended to assess the 3-D surface roughness and form errors. A double orientation method is used for separating the workpiece error from the spindle error. Software performs the data collection, processing, analysis and computation of 2-D and 3-D parameters. ~)
Exact Design of Aplanatic Microscope Objectives consisting of Two Conic Mirrors
Applied Optics, 1998
The necessary equations are derived for the design of aplanatic microscope objectives consisting of two mirrors, one concave and the other convex. The first-order parameters are calculated along with the conic constants of the mirrors, determined by means of an exact analysis to arrive at an aplanatic system.
The basic property discovered is described, along with its development on the ellipse and a brief transposition to parabola and hyperbola. Segment "e", defined on the normal to a conic section between a point thereon and its axis, and multiplied by a real number k, generates another conic section of the same type. The circumferences, halflines, line segments, etc. derived in particular cases of each type of conic section are described. It is shown that segment "e" is proportional to the cube root of the radius of curvature, which for the ellipse proves to be e=f(r^0,33). A study is made of the ruled surfaces deriving from the property, of their main cross sections, and of the locus of the parabolae. Emphasis is laid on the possibility of computerized treatment and numerical control, since the elementary mathematical definition of these surfaces facilitates construction with a numerically-controlled machine tool. A look at the particular cases suggests more applications. Finally, a look is taken at a few applications in architecture and engineering. These lend weight to the prospects of the patent for project design.
Proceedings of International Conference on Leading Edge Manufacturing in 21st century : LEM21
This paper introduces a schnidt lens manufacturing process, focusing on its axis-aymrnetr{c aspherical surface manufacturing by synthesizing ELID grinding and arc-enveloped grinding method. For test experiment, an offaxis spherical surface was ground to obtain suitable grinding and ELID conditions. [then, the large axis-aymmetric aspherical concave and convex were ground on the developed grinding system using #325, #1200 diarnond cast-iron bond wheels, Grinding characteristics such as attainable form accuracy, surface rougliness were investigated.
Journal of the European Optical Society-Rapid Publications, 2019
In order to remove mid-spatial frequency errors on aspheric and freeform surfaces, we have developed an aspheric smoothing tool which, unusually, is rigid. This has been proved feasible in the special case where the abrasive grit size exceeds the aspheric misfit, providing a cushion. Firstly, experimental parameters were derived from simulation of Influence Functions regarding misfit between the tool and the surface, which leads to dynamic Influence functions. Then the experimental part was polished into an aspheric surface from generated spherical surface. Thirdly, the choice of tool's shape parameters was completed with optimisation of conic constant and tilt angle. The tool was machined into aspheric shape with a single-point cutter. Finally, experiments were carried out to compare this tool with a standard spherical smoothing tool. The results showed that this aspheric smoothing tool can removal mid-spatial errors effectively on aspheric surfaces.