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About Us

A Little Bit of History Diffraction Team

Diffraction International Ltd. is a privately held optical engineering company based in Minnesota.

Diffraction International was founded abruptly in 1993 by president Steven Arnold following a round of layoffs by his former employer. The first year was difficult with no payroll and a costly legal dispute.

In 1994, the Company received a NASA Phase I SBIR award to develop a “CGH LUPI Interferometer for Aspheric Figure Metrology ”. By the time we received the SBIR Phase II award in 1995, we were doing enough commercial CGH null work that we had difficulty in completing the SBIR contract.

The NASA SBIR contract taught us that we are best at engineering and should avoid the manufacture of products with more parts than can be counted on our fingers. We also learned it was easier to produce high precision CGH nulls to be used external to existing commercial interferometers than to manufacture a special interferometer that could use photomask quality CGH nulls in its viewing arm.

One of the successful outcomes of our SBIR contract is Durango Interferometry Software. We had proposed to purchase commercial interferometry software compatible with a high resolution digital camera, but found none available. The commercial software in many ways lacked the flexibility we required. We decided to develop interferometry software more suitable to aspheric metrology. The SBIR contract ended, but we have never stopped developing Durango.

Products and Services

Our expertise is aspheric figure metrology. We can help you test aspheric optics more accurately and more easily using custom CGH Aspheric Nulls that will work with your current interferometer. We have designed and fabricated many hundreds of custom, one-of-a-kind CGH aspheric nulls for customers worldwide. We also offer several standard CGH cylinder nulls. Our diffractive CGH nulls are generally of lower cost than conventional refractive nulls.

Most of our CGH null work is customer proprietary. Of the few projects that we can mention publicly, we are most proud of the CGH nulls we produced for testing of the COSTAR correction optics for NASA’s Hubble Space Telescope. The COSTAR optics were manufactured by Tinsley Laboratories and our CGH nulls were the standard against which the several other testing methods were compared. The high profile COSTAR project also motivated us to improve our CGH technical documentation to its current high level.

Our Durango Interferometry Software works with any interferometer or camera type. Durango’s interactive graphical interface gives you unprecedented flexibility in data acquisition and analysis, all with very little typing and no need for programming. Durango optionally saves all the raw data, allowing you to do what-if analysis long after acquiring the data. Durango can be freely downloaded and distributed with your data files. A commercial license and hardware key are needed only to acquire new data.

We supply the few hardware accessories sometimes required for Durango to work with your interferometer. These include phase shift adapters, frame grabbers and DAC boards. If you prefer, we can provide a turnkey solution including the computer and installation.

Marketing and Sales

Our website is the most complete and up-to-date published information we have available. The best way to gain information about our Durango Interferometry Software is to download a free copy and review the features.

We occasionally exhibit at trade shows, giving you an opportunity to meet us face to face and evaluate our products hands-on.

Because our CGH Aspheric Nulls are custom one-of-a-kind and usually require engineer to engineer interaction, we sell directly worldwide without intermediate representatives. We do our best to make purchasing easy for our domestic and international customers. We usually offer preliminary CGH designs at no charge and quote firm fixed prices for custom orders.

Durango commercial software licenses and hardware accessories are sold both directly and through interferometer OEMs.


Our inhouse facilities are minimal, consisting mostly of computers and interferometers.

Diffraction International works with a network of contract manufacturing partners to produce its optical and mechanical products. This approach gives us the flexibility to adapt to varying order volumes and to take advantage of the most suitable manufacturing technologies while concentrating on what we do best: design and metrology. Shipment of critical work in process between physical locations is always overnight or same day.

Our primary optical design tool is OSLO from Lambda Research, Inc. This is because of OSLO’s versatility in modeling diffractive and aspheric surfaces and, especially, its compiled programming language (CCL). We have developed extensive proprietary CCL extensions to OSLO that enable us to rapidly design, analyze and document aspheric null test configurations. We maintain a license for ZEMAX from ZEMAX Development Corporation so as to better exchange optical design data with our several customers who use this tool. We once had a license for CODE V from Synopsys. We have written OSLO CCL extensions to export ZEMAX lens files and CODE V sequence files—and to verify these translations.

For opto-mechanical design, we maintain current licenses for AutoCAD Mechanical Desktop and AutoCAD Designer.

Our optical metrology equipment includes a Zygo 4-inch GPI interferometer and an ADE Phase Shift 4-inch MiniFiz interferometer. These phase shifting instruments are each equipped with our Durango Interferometry Software. Accessories include a 4-inch to 6-inch aperture converter, several Fizeau and return flats, and a few 4-inch Fizeau spheres.

We have custom-built optical aligners for framing standard sizes of CGH nulls. We also have lasers and power meters for measuring CGH diffraction efficiency at red and green wavelengths.

Employment Opportunities

If a position in a small, innovative and informal environment appeals to you, please send us your resume and letter. Candidates must apply directly to Diffraction International; no recruiting fee is available. Diffraction International is an equal opportunity employer.

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Copyright 2001–2019 Diffraction International
Page updated: 13 January 2019

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