These versatile lead salt photoconductors provide sensitive near infrared detection from 1 to 4.5 µm. Two stage TE cooled and uncooled versions are offered. We offer them AC coupled, since the 1/f noise, caused by the bias current, makes them poorly suited for DC operation. These detector heads include a preamplifier (requiring ±15 Vdc power) and a built-in fixed bias supply (requiring a +5 Vdc input).
Fig. 1 NEP of PbS and PbSe Detectors.
Which Detector Do I Choose?
Use the 3 x 3 mm room temperature detectors when signals are strong. Use the 1 x 3 mm, TE cooled detectors when signals are weak and you want to optimize your S/N, especially when using monochromators (the 1 x 3 mm aspect ratio is better matched to a monochromator slit shape).
You can use these detectors to monitor DC signals by periodically chopping the input beam. The signal can then be displayed on an oscilloscope, displayed on an RMS meter, such as our OPM™, or used as an input to a lock-in amplifier. The gain of the built-in amplifier can be matched to the display electronics. A higher gain is needed to bring the signal to the mV levels needed for oscilloscope display. The lowest gain is suitable for matching the noise voltage to the resolution capability of a narrow band lock-in amplifier.
Voltages and Controls
These detectors operate in a photoconductive mode. As such, they require ~100 V bias for proper operation. A bias power supply is built into the detector and all that is required is ±15 V for the amplifier and +5 V for the bias power supply. The 70703 / 70709 Power Supply will serve to provide the necessary voltages. Cooled units require the 77055 Temperature Controller to power and stabilize them.
Mounting and Cables
These mounted detectors have a 1.5 Inch Series female flange. All the necessary interconnecting cables are shipped with the detectors.
Tech Note
The noise level of these detectors can be significantly increased by exposure to UV or blue light. They usually recover in the dark, but this can take many hours. Protect them from unnecessary exposure.
