LLM-3 optical power meter employs a high-quality PIN photodiode as the photoreceiver to achieve high detection sensitivity down to 0.1 µW level. It is pre-calibrated at four wavelengths of 514 nm, 532 nm, 632.8 nm, and 650 nm in factory so that it can provide accurate power measurements in a broad wavelength range from 400 nm to 1100 nm. It can be interfaced with a computer through a USB port.