Abstract: A multipurpose all-wavelength intensity monitor for determining and monitoring the output intensity of ultraviolet sources. The unit measures ultraviolet wavelengths of 365 nanometers, 300-312 nanometers, and 254 nanometers without changing sensors or switches and the monitor is based on measurement utilizing a time period with a precalibrated microjuole setting. The intensity is determined by measuring the time period elapsed from the beginning of the monitoring to a tone sound which indicates the end of the monitoring period. This time period is compared to a chart with a curve for each of the ultraviolet wavelengths. Using the curve with the known time elapsed will indicate the intensity output. The monitor indicates loss of intensity by comparing lengthening of the monitored time or by indicating the actual intensity using the time output curves. A modified stopwatch can start the timing when unit is actuated and stop the timing when tone is sounded.