No detector has a constant spectral responsivity under all conditions of use. For instance, the responsivity of photodiode detectors falls off above a certain incident power level due to saturation effects. Full evaluation of a detector requires characterisation of such effects. This information allows the identification of the detector with the best performance for a particular application. Also, a detector to be used for calibration purposes should be fully characterised in order to evaluate the uncertainty of such calibrations.
In all cases the detector under test is compared with a standard detector of known spectral responsivity / quantum efficiency.
300F Monochromator is used to select a narrow wavelength band from a broad band quartz halogen lamp. Wavelength range of monochromator is between 200 – 2000 nm. The wavelength can readily be tuned continuously allowing measurement of spectral responsivity across the wavelength range for which the detector is used
|Optical path||:||Czerny-Turner configuration|
|Scanning range||:|| 200 – 2000 nm (UV requires Special Lamp)
System comes with Quartz Halogen Lamp which Wavelength Range is 350 – 2000 nm
for UV range less than 350 nm special lamp is required
|Resolution||:||0.1nm (@ 546 nm, 10 μm slit width)|
|Wavelength accuracy||:||≤ 0.2 nm|
|Wavelength repeatability||:||≤ 0.1 nm|
|Incident power levels||:||10-10 – 10-3 W range|
|Laser Wavelength||:||532 nm|
|Chopper frequency||:||400 Hz|
|Maximum beam||:||15 x 10 mm|
|Voltage range||:||1 to -1 V|
|Current range||:||0.1 uA to 0.75 A|
HOLMARC Model: HO-PDC-01 designed for characterisation / measurement of the following detector parameters:
Linearity range : This is the range of incident radiant power levels over which the detector output varies linearly with incident power. (Laser-based methods is used for measuring saturation threshold of a detector).
Spatial non-uniformity of response : The variation of responsivity across the active area of a detector is determined by scanning a small spot of radiation at a selected wavelength over the surface.
Noise Equivalent Power (NEP) : the incident radiant power at a specific wavelength and modulation frequency necessary to produce a signal-tonoise ratio of 1 at the detector output.
Temperature coefficient of response : the variation of responsivity with temperature
Detector shunt resistance : the slope of the current-voltage curve of a photovoltaic detector at zero-volt bias.