Oriel's new diode array radiometer consists of a flat focal plane spectrograph and a diode array detector, interfaced to a standard XT or AT type computer. The spectrograph has interchangeable gratings, and can be set for almost any wavelength range from 180 to 1100 nm. The diode array detector is thermally stabilized to 0.1°C, and can acquire an entire spectrum in only 5 milliseconds, it can take a sequence of scans, and can follow the time course of an optical change. The results can be graphically displayed in absolute energy units verses wavelength or time. Radiometric capability is achieved by using an NIST traceable light source to calibrate the system in situ for the wavelength region of interest. This takes into account front end fiber optic guides, optical filters, and spectrograph efficiency. Extensive software semi-automates this process, providing automatic calibration of the radiometer against the output energy curve of the source. The radiometer can exactly quantify exposure levels of UV-A and UV-B radiation. This is more accurate than the approximate values derived using optical filters. The system can also simulate other types of detectors defined by the user, and the data can be presented in a variety of photometric units. The diode array detector is 25 mm long and can be used for linear radiometric imaging when used with bandpass filters. A camera and assortment of lenses may be used in conjunction with the diode array detector for telephoto, wide-angle, or micro imaging.