Where does grating collide?

In optics, a diffraction grating is a surface ruled with many fine, regularly spaced lines or grooves that diffract light so that different wavelengths emerge at different angles, spreading a beam into a high-resolution spectrum. Rayleigh's 1874 On the manufacture and theory of diffraction-gratings set out the theory of the ruled grating and the factors that govern its resolving power. The referent is a periodic optical device that disperses light by interference, characterised by its line spacing, diffraction orders, and resolving power, and it is a different construct from the striped pattern used to probe vision.[1]

Unit

The dispersion and resolving power set by the line spacing and orders

Recovery means

Not applicable

Measured by

Specified by groove spacing, the grating equation relating angle to wavelength, and the resolving power across diffraction orders

In vision science, a grating is a visual stimulus of parallel light and dark stripes, usually with a sinusoidal luminance profile, used to measure how well the visual system resolves patterns at different spatial frequencies and contrasts. Campbell and Robson's 1968 Application of Fourier analysis to the visibility of gratings used such gratings to establish the contrast sensitivity function and argued the visual system analyses images into spatial-frequency components. The referent is a controlled periodic pattern presented to an observer, defined by its spatial frequency, contrast, and orientation, and it is unrelated to the ruled optical device beyond the shared image of evenly spaced lines.[2]

Unit

The spatial frequency, contrast, and orientation of the striped pattern

Recovery means

Not applicable

Measured by

Defined by spatial frequency (cycles per degree) and contrast; used to trace the contrast sensitivity function of an observer