A system for the throughput detection and feedback of optical energy for making sure of white balance of the LED array in a flat fluorescent light source when the LED array in emitting light by respectively connecting in series a selected LED lamp respectively from RGB LED groups in an LED array to an optical energy sensor to convert optical energy into equivalent amperage, then voltage analog signals to digital signals for a CPU to compare and solve the difference of optical energy to improve voltage output, which then regulated by a driver and fed back to the LED array.