The NRT-150 Log Detector is a useful photodiode amplifier designed to measure low light levels, down to - 60 dBm.

July 26, 2016


We initially developed the NRT-150 to help customers using the NRT-2500 or NRT-250 for Tracker applications, specifically when trying to track to a minimum light level. This problem is challenging. On one hand the goal is to minimize the number of photons, yet you need photons to generate a reliable Tracker feedback signal. With a (normal) linear photodiode amplifier, the voltage gets too small to track as the minimization darkens the output. Using the NRT-150 log amplifier ‘compresses’ the high power voltage output and ‘expands’ the voltage output at lower optical power.

Below is an example of the log response through almost 6 decades of detected optical power.

NRT-150 calibration curve

Typical calibration of optical power to voltage out for the NRT-150

Key Specifications

  1. Calibrated from 0 dBm to below -60 dBm
  2. Response approximately 200 kHz
  3. Analog (BNC) voltage output
  4. Compact size

For more information, please contact New Ridge Technologies: or call: +1-410-753-3055