Polychromators are spectrometers that make simultaneous measurements of the spectral distribution for various wavelengths with the aid of a suitable detector like the photodiode array. without rotation of the grating. As shown in Fig.5, light from A is separated into spectral components by the concave grating and this spectrum is then projected onto the face of the detector (between B1 and B2). The spectral image plane has been designed to be as flat as possible, and aberration characteristics such as coma and astigmatism have been carefully minimized. Select the concave grating most suitable for the application from those listed in Table 3. Position of diffracted light on the detector surface in polar coordinates is as follows.
In case of polychromator, the reciprocal linear dispersion is as follows.
The various parameters are explained below.
Groove density N :
The groove density at the center of the concave grating.
Dispersion D :
The value obtained by dividing the wavelength range (λ1 to λ2) by the detector length L.
Wavelength range Nmλ1 to Nmλ2 :
The optimum wavelength range for the Shimadzu design. Outside this range, aberrations become larger and imaging performance deteriorates. λ1 and λ2 respectively represent the minimum and maximum wavelengths.
Detector length L :
Length of detector required for application in the above wavelength range.
Blaze wavelength λB :
The blaze wavelength λB for the mounting parameter and not the blaze wavelength for the Littrow configuration λB(Litt). Refer to Blaze Wavelength under Overview of Gratings for details.
Mounting Parameters (Refer to Fig.5.)
Dimensions W, H, and T :
"W" is the width perpendicular to the grooves. "H" is the height parallel to the grooves. "T" is the thickness at the center. (Refer to Fig.3.)
Code number :
Specify a code number when ordering.