Detailed Product Wanted Description

Concave Blazed Holographic Gratings
Ideal for Flat-Field and Imaging Applications
Aberration Corrected to Eliminate Astigmatism
Simplifies System Design by Eliminating Need for Other Image-Forming Optical Elements

Concave gratings accomplish the task of two optical elements in a single, easily integrated component. The gratings themselves are blazed holographic types, ensuring excellent efficiency and minimum stray-light, compared to standard blazed or holographic gratings. They are formed on precision concave substrates, allowing the grating to serve as both the primary dispersive element and the primary focusing element. This unique feature greatly simplifies system design and system integration, allowing for more compact and sensitive instrumentation. 
Concave gratings are critical components in a variety of spectroscopic instrumentation. They are quite useful in analytical instruments, ranging from food analysis to plastics manufacturing and process quality assurance. They are also ideal for applications in optical communications, biotechnology, colorimetry, chromatography, and medical instrumentation. 
The performance of these gratings is greatly enhanced by advanced design and manufacturing techniques used in their production. First, a holographic master grating is created by using the optimum exposure method for correcting aberrations, which includes an aspherical wave exposure interference technique. Then, a patented ion-beam etching technology is employed to create the standard "sawtooth" design common to ruled gratings, eliminating the periodic structure errors that cause stray light. This process creates aberration-corrected grooves that are neither equidistant nor parallel, ensuring near-perfect images of the entrance slit on the detector. 
 
Material:  Soda Lime
Clear Aperture:  80% of Diameter
Surface Quality:  60-40
Dimensional Tolerances:  +/-0.3mm
Groove Density Tolerance: +/-2.0 grooves/mm
Blaze Wavelength Tolerance: +/-10% of blaze wavelength
Relative Diffraction Efficiency: >50%

Holographic Gratings
Holographic gratings are formed by an interference fringe field of two laser beams whose standing wave pattern is exposed to a polished substrate coated with photo resist. Processing of the exposed medium results in a pattern of straight lines with a sinusoidal cross section. 
Holographic gratings produce less stray light than ruled gratings. They can also be produced with up to 3600 grooves per millimeter for greater theoretical resolving power. Due to their sinusoidal cross section, holographic gratings cannot be easily blazed and their efficiency is usually considerably less than a comparable ruled grating. There are, however, special exceptions which should be noted. When groove spacing to wavelength ratio is near one, a holographic grating has virtually the same efficiency as the ruled version. Also, a holographic grating with 1800 grooves per millimeter has the same efficiency at 500nm as a blazed ruled grating. Holographic master gratings are replicated by a process identical to that used for ruled gratings. 
Material:  Float glass
Clear Aperture:  80% of Diameter
Surface Quality:  60-40
Dimensional Tolerances:  +/-0.5mm
Groove Density Tolerance: +/-2.0 grooves/mm
Relative Diffraction Efficiency: 40-65%
Diffraction Gratings
A diffraction grating is an optical component that separates (diffracts) polychromatic (white) light into its component wavelengths. Each grating is fabricated from a highly accurate master grating that is copied many times. The duplication process is described below for replicated gratings. 
These high-quality instrument-grade ruled gratings will satisfy almost all of your diffraction requirements, especially when high efficiency is the primary concern. Gratings can be selected by size, groove spacing and blaze wavelength. Theoretical resolving power is directly proportional to the number of grooves per millimeter ruled into the master grating. The blaze angle and groove spacing determines the specific wavelength and spectral region where the grating has its maximum efficiency. 
Diffraction ruled gratings are used in a variety of monochromators for research, student and industry use. Almost all commercially available spectrophotometers (ultraviolet, visible, infrared, fluorescence, Raman, atomic absorption) utilize diffraction gratings to select specific wavelengths or scan over a wavelength interval. As a general rule, replicated ruled gratings should be used when high peak efficiency and throughput is required. Replicated holographic gratings should be used when minimum stray light is critical and high resolution is needed. Note: Damage thresholds for both ruled and holographic gratings are 350 milli-joules/cm2 for pulsed lasers and 40 Watts/cm2 for CW lasers.