At first, I conducted tests to check if the LED brightness could decrease to the desired level using a photoelectronic sensor (SEN-09088).

For the photoelectronic sensor, which has a known value range of 0-4095, I needed to adjust the mapping values to match the amount of light exposed to the sensor. By reducing the Particle Cloud's stream reading values to a range of 2500-3600, I was able to visually distinguish the brightness of the light. (Please enlarge the video to the full screen below)