Optical  System  Simulation  Software


The Student Edition of DIFFRACT

The latest release of DIFFRACT (Version 8.4) is now available both as the General Edition and the Student Edition. At $450 per copy, the Student Edition is affordable to those who wish to learn the diffraction phenomena of classical Optics without paying the higher price of the General Edition that is used by industrial scientists and engineers for high-precision design and tolerancing of optical instruments. With the few exceptions noted below, the Student Edition provides all the features available in the General Edition, the main restriction being the mesh size, which is limited to 512 by 512 in the Student Edition. The Student user can thus simulate the various phenomena of classical Optics, observe the patterns of light propagating through a simulated system consisting of discrete optical elements, and obtain numerical results with a reasonable degree of accuracy; what he/she does not obtain is the very high accuracy that is sometimes required by the industry for instrument design and fabrication.

The Student Edition of DIFFRACT has been classroom tested; it is designed with the needs of both teachers and students of Optics in mind. Use it to learn more about near-field and far-field diffraction phenomena; the focusing action of lenses with and without aberrations; polarization optics; interferometry; multilayer stacks; birefringent crystals; microscopy; optical disk systems; magneto-optical Faraday and Kerr effects; total internal reflection; the Goos-Hänchen effect; conical internal refraction; geometric-optical systems consisting of flat, spherical, conical, and aspherical surfaces; gradient-index (GRIN) lenses; diffraction gratings; the Talbot effect; Fresnel biprisms; coherent imaging; and much more.

The main differences between the General Edition and the Student Edition of DIFFRACT are listed below.

(1) Mesh Size: Student Edition limits to 512 by 512 the discrete mesh on which the cross-section of the beam is sampled. The General Edition, on the other hand, allows the user to set the mesh size arbitrarily. Of course the computer must have sufficient memory to support the mesh in either case. For a 512 by 512 mesh the minimum RAM requirement is 32 MByte.

(2) In the Geometric-optical_System option of DIFFRACT, the number of optical surfaces (Glass, Aperture, Mirror) is limited to 10 in the Student Edition. The General Edition has no such limits.

(3) In the Multilayer option, the number of layers (metal, dielectric, birefringent, magneto-optic, etc.) is limited to 10 in the Student Edition. Again the General Edition has no such limits.

(4) The Lens option offers seven lenses in the General Edition: Positive_focusing, Collimator, General-purpose Lens, Astigmat, Cylindrical, Ring_Toric Lens, and Split Lens. In the Student Edition only Positive_focusing, Collimator, and Astigmat, and Cylindrical are available.

(5) The Positive_focusing lens may be treated in two different ways: (a) the standard method of classical diffraction theory based on the stationary-phase approximation to one of the Fourier integrals; (b) a novel method that requires a large mesh but avoids the stationary-phase approximation. (In essentially all cases of practical interest the results obtained by the stationary-phase approximation are indistinguishable from the more accurate results.) The Student Edition offers only the standard method.

(6) The General Edition offers four types of segmented photodetectors: Quad, Split, Phi, and Differential. Only the first two are available in the Student Edition.

(7) The Optical_Disk option of the General Edition allows the user to choose from the following menu: Read-only Disk (e.g., CD, DVD), Writable disk (e.g., CD-Recordable, Phase-change WORM, Phase-change rewritable), Magneto-optic (both light-intensity-modulation and magnetic-field-modulation types), and Dye-Polymer media. In the Student Edition only the Read-only disk is available. This feature is powerful enough to show students the various effects of diffraction from CD pits, autofocusing schemes, track-following techniques based on diffraction from pit-edges, etc.

(8) The Grating option in the General Edition allows the user to import the exact reflection/transmission coefficients of the grating through a data-file. This feature is not available in the Student Edition. Both editions, however, allow a very general phase/amplitude grating with trapezoidal groove cross-sections to be defined. DIFFRACT treats this grating in a quasi-scalar approximation. The students can thus learn about many features of the gratings (such as normal and oblique incidence, conical diffraction, diffraction of focused beams from gratings, etc.), observe the diffracted orders in their proper positions, and view the near-filed and far-filed of the grating. What they do not get is accurate values for diffraction efficiencies; they also do not see exotic features such as surface plasmon excitations and Wood's anomalies. Of course, the General Edition would not be able to predict these exotic features either; only when an exact solution of Maxwell's equations for the grating is available through some other source, will the General Edition be able to import the correct reflection/transmission coefficients and superpose them to yield the accurate results.

To order a copy of the Student Edition of DIFFRACT please mail your check, money-order, or purchase order to MM Research, Inc., 5748 N. Camino del Conde, Tucson, Arizona 85718.

Institutions may also fax their purchase orders to MM Research, Inc. at (520) 299-7996. In the United States please allow 7 to 10 days for delivery; overseas orders may require two weeks or more.


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