Blazed grating
Encyclopedia
A blazed grating is a special type of diffraction grating
.
Blazed gratings produce maximum efficiency at a specified wavelength
; that is, a diffraction grating that is "blazed at 250nm" will operate most efficiently when light
with a wavelength of 250 nm passes through the grating.
Like standard diffraction gratings, blazed gratings diffract incoming light using a series of grooves. However, in blazed gratings the grooves have been manufactured such that they form right angles with a specified "blaze angle," which is the angular distance from the surface normal
of the diffraction plate. The magnitude of the blaze angle determines the wavelength at which the grating will be most efficient.
Blazed gratings are useful in planet-finding astronomy, and are used on the successful HARPS echelle
spectrograph
.
Diffraction grating
In optics, a diffraction grating is an optical component with a periodic structure, which splits and diffracts light into several beams travelling in different directions. The directions of these beams depend on the spacing of the grating and the wavelength of the light so that the grating acts as...
.
Blazed gratings produce maximum efficiency at a specified wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
; that is, a diffraction grating that is "blazed at 250nm" will operate most efficiently when light
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
with a wavelength of 250 nm passes through the grating.
Like standard diffraction gratings, blazed gratings diffract incoming light using a series of grooves. However, in blazed gratings the grooves have been manufactured such that they form right angles with a specified "blaze angle," which is the angular distance from the surface normal
Surface normal
A surface normal, or simply normal, to a flat surface is a vector that is perpendicular to that surface. A normal to a non-flat surface at a point P on the surface is a vector perpendicular to the tangent plane to that surface at P. The word "normal" is also used as an adjective: a line normal to a...
of the diffraction plate. The magnitude of the blaze angle determines the wavelength at which the grating will be most efficient.
Blazed gratings are useful in planet-finding astronomy, and are used on the successful HARPS echelle
Echelle grating
An echelle grating is a type of diffraction grating which is characterised by a relatively low groove density but is optimized for high diffraction orders. Echelle gratings are, like other types of diffraction grating, used in spectrometers and similar instruments, such as HARPS, and numerous...
spectrograph
Spectrograph
A spectrograph is an instrument that separates an incoming wave into a frequency spectrum. There are several kinds of machines referred to as spectrographs, depending on the precise nature of the waves...
.