Spectrum Technologies offers the LightScout DLI 100 light meter to measure the light falling on plants. It is an affordable first step in measuring the light intensity levels affecting crops. The meter is sold in sets of three to compare light level intensities within or outside the greenhouse. With a push of a button, the DLI 100 Meter records light intensity for a 24-hour period and then calculates the daily light integral (DLI). Real-time intensity levels are shown every 4 seconds.