The S450 handheld energy/power optometer from UDT Instruments is designed for laboratory or field environments. Featuring highly sensitive microprocessor control, it offers three data-presentation options: direct display measurement with analog bar, RS-232 computer interface and programmable analog voltage output. Compatible with the company’s sensor heads, it can be configured as a radiometer, a photometer or an energy meter with seven measurement decades. Suitable for low-light applications, it enables measurements in the 10-pA range with less than 1% uncertainty. The model provides wide dynamic range and computerized high-speed update rates, and it stores nine continuous or 50 single-point calibrations.