A phototransistor with maximum response in the infrared region of the spectrum at around 940nm (IPC-4566-W). This is near to the visible region of the spectrum. The phototransistor is mounted on the end of a fibreglass wand, fitted with a 250mm lead and two 4mm connectors. When connected to a suitable voltmeter (e.g. IPC-1904-M, 2VDC digital voltmeter) the probe will produce a qualitative reading proportional to the amount of infrared radiation incident on it’s sensitive face.
The probe is supplied with user instructions which also include details of a simple experiment using a prism.