Detector: SHD033/W
Range: 3 x 10-13 to 4.5 x 10-5 W/cm2
Spectrum: 200 to 1050 nm, 750 peak
Size: 69 mm x 42 mm dia.
Detector: SHD240/W
Range: 1 x 10-12 to 2 x 10-7 W/cm2
Spectrum: 185 to 320 nm, 240 peak
Size: 101 mm x 42 mm dia.
The SHD033 matches the sensitivity of a PMT using solid state amplification of a silicon photodiode. The proprietary preamp is unique in that it preamplifies the current-chopped junction charge of the cell, providing an 82 dB linear response. Built-in temperature control and leakage shielding minimize noise and dark current. The special Silicon cell has a broad spectral range with excellent sensitivity in the near IR, recovers rapidly from overload (such as direct sunlight) without damage, and maintains its calibration integrity over time.Since the complex preamplification circuitry is located within the actual detector head, noise is held to a minimum. The remote circuitry requires input voltages automatically provided by the IL1700 and IL1800 Research Radiometers (not available for use with the IL1400A).
The SHD240 uses the same preamplification in conjunction with a Cs-Te solar-blind vacuum phototube with a UV glass window. This high stability device maintains ± 1% sensitivity for ten years. The flat 8 mm diameter cathode provides a large, well defined receiving surface for accurate geometry calculations. The SHD240 contains temperature regulation, for operation from -80°C to +50°C.
Both of the SHD detectors have been designed to operate with the IL1820 Lock-In Radiometer System, for 2 Hz chopped measurement and phased zeroing. This results in a 100:1 improvement in signal to noise.
Detector: PM271C
Spectrum: 200 to 675 nm, 390 peak, S-5
Range: 6 x 10-14 to 6 x 10-7 W/cm2
Size: 161 x 50 x 38 mm
Detector: PM271D
Spectrum: 200 to 850 nm, 420 peak, S-20
Range: 3 x 10-14 to 3 x 10-7 W/cm2
Size: 161 x 50 x 38 mm
PM271 SERIES PHOTOMULTIPLIERS: Photomultipliers provide high internal current gain by combining the external photoelectric effect (semiconductor photodiodes use the internal photoelectric effect) with low noise secondary electron multiplication. A high voltage regulated supply, such as the IL760D Photomultiplier Power Supply, is required to provide the appropriate cathode, dynode, and anode voltages. The response time for PMT's is typically very fast (< 10 nS), and is a function of the dynode voltage. Photomultipliers typically offer a six decade dynamic range with excellent linearity over most of that range. Although PMT's are relatively immune to thermal "Johnson" noise, the noise equivalent power is limited by dark current, which can be reduced by cooling the photomultiplier. In addition, photomultipliers require more frequent recalibration, as they do not exhibit the long term stability inherent to solid state devices.
