Rochester, NY, United States
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Forbes G.W.,QED Technologies Inc.
Latin America Optics and Photonics Conference, LAOP 2014 | Year: 2014

Precision optics possess increasingly complex desired surface shapes. Production challenges associated with lack of local spherical symmetry mean that as-built shapes are even more complex, so analytical tools for specifying and characterising them become essential. © OSA 2014.


Forbes G.W.,QED Technologies Inc.
Optics Express | Year: 2010

Whether in design or the various stages of fabrication and testing,an effective representation of an asphere's shape is critical. Some algorithms are given for implementing tailored polynomials that are ideally suited to these needs. With minimal coding, these results allow a recently introduced orthogonal polynomial basis to be employed to arbitrary orders. Interestingly, these robust and efficient methods are enabled by the introduction of an auxiliary polynomial basis. © 2010 Optical Society of America.


Forbes G.W.,QED Technologies Inc.
Optics Express | Year: 2010

Mathematical methods that are poorly known in the field of optics are adapted and shown to have striking significance. Orthogonal polynomials are common tools in physics and optics, but problems are encountered when they are used to higher orders. Applications to arbitrarily high orders are shown to be enabled by remarkably simple and robust algorithms that are derived from well known recurrence relations. Such methods are demonstrated for a couple of familiar optical applications where, just as in other areas, there is a clear trend to higher orders. © 2010 Optical Society of America.


Forbes G.W.,QED Technologies Inc.
Optics Express | Year: 2011

Some simple measures of the difficulty of a variety of steps in asphere fabrication are defined by reference to fundamental geometric considerations. It is shown that effective approximations can then be exploited when an asphere's shape is characterized by using a particular orthogonal basis. The efficiency of the results allows them to be used not only as quick manufacturability estimates at the production end, but more importantly as part of an efficient design process that can boost the resulting optical systems' cost-effectiveness. © 2011 Optical Society of America.


Forbes G.W.,QED Technologies Inc.
Optics Express | Year: 2013

Orthogonality is exploited for fitting analytically-specified freeform shapes in terms of orthogonal polynomials. The end result is expressed in terms of FFTs coupled to a simple explicit form of Gaussian quadrature. Its efficiency opens the possibilities for proceeding to arbitrary numbers of polynomial terms. This is shown to create promising options for quantifying and filtering the mid-spatial frequency structure within circular domains from measurements of as-built parts. © 2013 Optical Society of America.


Forbes G.W.,QED Technologies Inc.
Optics Express | Year: 2012

A recently introduced method for characterizing the shape of rotationally symmetric aspheres is generalized here for application to a wide class of freeform optics. New sets of orthogonal polynomials are introduced along with robust and efficient algorithms for computing the surface shape as well as its derivatives of any order. By construction, the associated characterization offers a rough interpretation of shape at a glance and it facilitates a range of estimates of manufacturability. © 2012 Optical Society of America.


Patent
QED Technologies Inc. | Date: 2010-03-02

A system for magnetorheological finishing of a substrate. A spherical wheel meant for carrying a magnetorheological finishing fluid houses a variable-field permanent magnet system having north and south iron pole pieces separated by primary and secondary gaps with a cylindrical cavity bored through the center. A cylindrical permanent magnet magnetized normal to the cylinder axis is rotatably disposed in the cavity. An actuator allows rotation of the permanent magnet to any angle, which rotation changes the distribution of flux in the magnetic circuit through the pole pieces. Thus, one can control field intensity in the gaps by positioning the permanent magnet at whatever angle provides the required field strength. Because the field also passes above the pole pieces, defining a fringing field outside the wheel surface, the variable field extends through a layer of MR fluid on the wheel, thus varying the stiffness of the MR fluid as may be desired for finishing control.


Patent
QED Technologies Inc. | Date: 2013-11-22

An instrument for measuring aspheric optical surfaces includes both an optical wavefront sensor and a single-point optical profilometer. The optical wavefront sensor measures surface height variations throughout one or more areas of an aspheric test surface. The single-point profilometer measures surface height variations along one or more traces on the aspheric test surface. At least one of the traces intersects at least one of the areas, and respective spatial frames of reference for the traces and areas are relatively adapted to each other by minimizing differences between points of nominal coincidence between the areas and traces.


A system for sensing and controlling concentration of magnetic particles in magnetorheological fluid comprising a wire coil and an AC voltage generator that, when energized, creates a magnetic flux field including a fringing field. When the fringing field extends through the magnetorheological fluid, the impedance in the circuit is proportional to the concentration of magnetic particles. A reference wire coil identical to the sensing wire coil is connected therewith. A demodulator is connected to each of the coils sends an impedance difference signal to a feedback controller connected to controllable dispensing apparatus for adding a calculated amount of replenishing fluid to the magnetorheological fluid. The system may be incorporated into an integrated fluid management module having apparatus for receiving and replenishing spent magnetorheological fluid and a sensor system in accordance with the present invention for use in a magnetorheological finishing system having a carrier wheel.


Patent
QED Technologies Inc. | Date: 2010-12-23

A system for magnetorheological finishing of a substrate. An integrated fluid management module (IFMM) provides dynamic control of the rheological fluid properties of the MR fluid on a conventional MR finishing apparatus, and dispensing of the fluid to the wheel. A magnetically shielded chamber charged with MR fluid is in contact with the carrier wheel. A transverse line removes the spent MR fluid from the wheel as the ribbon leaves the work zone. Replenishment fluid is added to the chamber via a dripper, and preferably an electric mixer agitates MR fluid in the chamber. A grooved magnetically-shielded insert at the exit of the chamber forms a polishing ribbon on the carrier wheel as the wheel is turned. A sensor sensitive to concentration of magnetic particles provides a signal for control of MR fluid properties, particularly, water content in the MR fluid. Means is provided for cooling fluid within the chamber.

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