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.