Reflective Ruled 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.

Manufacturing of Ruled Gratings

Ruled diffraction gratings are produced by ruling a series of closely spaced, straight parallel grooves into an optically flat aluminum coated substrate, known as the “master grating.” Precise, interferometrically-controlled ruling engines utilize a very fine diamond tool to form a sawtooth-shaped groove profile at a given angle (commonly referred to as the blaze angle) on the surface of a prepared substrate. The replication process begins with the surface contour of a ruled master grating being vacuum deposition-coated with an extremely thin separation layer. An aluminum coating is then deposited on top of this separation layer. Then, an epoxy-coated flat glass substrate is placed on top of the layer-covered master, duplicating the grooved surface. The combination is cured and the process is finished when the replicated grating is separated from the master grating.