Grating holographically ruled

The key performance indicator for any instrument is the overall SNR, which evaluates the ratio of diffracted tight to unwanted tight. Because this is an instrument function there is no clear rule-of-thumb that indicates what grating type, ruled or holographic, might provide the higher SNR. It is the SNR of an instrument that will determine the system linearity and dynamic range. 

Holographic grating A grating that has been produced by optical interference on a coated glass plate rather than by mechanical ruling. 

Ruled gratings are mainly used in AA instruments. Holographic gratings have less irregularities and therefore lower stray radiation, but this is not so important in AAS as it is, for example, in plasma-AES. From the ruled master gratings (often aluminium) copies can be prepared, which are less expensive. 

Figure 7 Effect of grating type on the efficiency (A) ruled grating blazed at 240 nm (B) holographic grating blazed at 260 nm (C) sinusoidal holographic grating.

Holographic Very low stray light, high efficiency, low cost Hayat GS and Pienchard G (1968) Handbook of Diffraction Gratings. Ruled and Holographic. Jobin-Yvon. 

Briefly describe how a holographic grating is produced. What is the advantage of this approach over a mechanically ruled grating ... 

The work dealt with phase and amplitude-phase transmission hologram-gratings with different thicknesses and constants, constructed, as a rule, in a symmetrical (or close to that) configuration of interfering beams relative to the sample surface. Main measured holographic parameters were the diffraction efficiency (DE) and selectivity contour of holograms, constructed under different recording and post-exposure treatment conditions. 

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