Changchun Hengyi Optics Supply Gratings

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%

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Contact Name: Hellen Lu
Company Name: Changchun Hengyi Optics Co., Ltd
Email: Hellenzihan@hyoptics.net
Tel: 86-431-85299928
Fax: 86-431-85299928
Street Address: #5-9, Dongling South
Street, Changchun, Jilin, China