Welcome to our virtual Efficiency Testing Laboratory !
Despite its "virtual" nature, ETL enables one to quite objectively test and compare the efficiency of real gratings. In what follows we attempt to carry out a series of standard tests using, in general, commercially available tools and to demonstrate examples of Efficiency Certificates for diffraction gratings. The prime objective of the Efficiency TestLab is to minimize discrepancies between calculated and measured efficiency data for all types of gratings, as well as to give some guidance for scientists and engineers on how to produce the next generation of gratings and their associated instruments. The objectives of our joint efforts are the following:
To achieve good agreement between measured and calculated efficiency data for various gratings and wavelengths.
To work out recommendations on measuring parameters of real gratings and on methods for the precise modeling of gratings diffraction properties using these parameters.
To issue gratings Efficiency Certificates for some important cases involving computed and measured efficiency curves.
Together with the
we issue our online Efficiency Certificates. What is the Efficiency Certificate for a diffraction grating ? This is a procedure for calculating the grating efficiency in a working range of wavelengths which is based on accurate methods of prediction and agrees closely (to an accuracy of 10% or better) with experimental data at all reference points. The reliability of an Efficiency Certificate depends upon a strategy of detailed theoretical and experimental investigation of diffraction properties of the grating, including direct measurements of its efficiency, atomic-force microscopy of the profile of its boundaries, and factual data on the optical constants of its layers materials. The Efficiency Certificate of a real grating issued on the basis of this strategy makes it possible thereafter to readily predict, by the use of accurate numerical modeling, the efficiency of any order, in any wavelength range of interest and under any changes of its physical parameters or radiation conditions. Efficiency Certificates are of paramount importance for valuable and high-priced gratings, for which their efficiency cannot be measured for all wavelength ranges and operating conditions, as well as in instances of possible degradation of the grating parameters by the action of a variety of factors.
This is the world's first comprehensive demonstration of the results of grating efficiency tests obtained using modern technologies. The NASA GSFC Optics Branch
has a Diffraction Grating Evaluation Facility (DGEF)
. It is a world-class, advanced resource which was developed at Goddard to evaluate optical components such as diffraction gratings, mirrors, and filters, as well as detection systems used in space instrumentation. The NRL Space Science Division UV and X-Ray Spectroscopy Section
provides an ultrahigh vacuum facility for development and calibration of extreme ultraviolet (EUV) and X-ray optics and instrumentation using monochromatic synchrotron radiation. The Richardson Gratings of Newport Corp.
is a world leader in the design and manufacture of ruled and holographic diffraction gratings for industrial, academic and scientific markets. The International Intellectual Group, Inc. (I.I.G., Inc.) has 20 years of experience in developing exact methods for calculating gratings efficiency and 15 years of experience in creating and selling various commercial programs based on accurate theories. Our I.I.G. experts amassed a large amount of information on gratings manufacture and on both measuring and comparing theory with experiments in a range extending from X-rays to microwaves.
Moreover, today we make wide use of the most general integral theory (MIM
), which allows us to deal with practically all kinds of gratings including some limiting cases for which this is the only method available.
We launched the project working in close cooperation with our associates from NASA GSFC
, NRL SSD
, and Richardson Gratings
, but all organizations, companies, or individuals are welcome to take part in it. At the same time we would greatly appreciate our visitors' comments and any useful information concerning the subject.