Agilent Technologies Cary 8454 Operator's Manual page 25

• Slit
• Grating
• Diode Array
Agilent Cary 8454 UV-Visible Spectroscopy System Operator's Manual
Agilent Cary 8454 UV-Visible Spectrophotometer — Overview
The slit is a narrow aperture in a plate located at the focus of the
spectrograph lens. It is exactly the size of one of the photo diodes in the
photo diode array. By limiting the size of the incoming light beam, the slit
makes sure that each band of wavelengths is projected onto only the
appropriate photodiode.
The combination of dispersion and spectral imaging is accomplished by
using a concave holographic grating. The grating disperses the light onto
the diode array at an angle linear proportional to the wavelength.
The photodiode array is the heart of the spectrograph. It is a series of 1024
individual photodiodes and control circuits etched onto a semiconductor
chip. With a wavelength range from 190 nm to 1100 nm the sampling
interval is about 0.9 nm.
Introduction to Your System 2
25