For our first experiment, we decided on a straightforward comparison of three flicker frequencies: 0 Hz (DC), 100 Hz and 500 Hz, all with a square wave, 100 percent modulation
, and a 50 percent duty cycle (Figure 1).
One major benefit of solid state street lights is that in the wee hours of the morning, the lights can be dimmed to 50 percent modulation
, delivering significant power savings.
For example, a large visual target of mean luminance 450 cd/m2 flickering at 60 Hz with a modulation of 30 percent can be seen as flickering while the same target at the lower light level of 40 cd/sq m is below the threshold even for 100 percent modulation
. Similarly, modeling of the ERG response to flickering light, extending well above the perceivable flicker frequency, for example, up to 200 Hz, can be modeled in several stages.
For the current design, shown in Figure 5, a theoretically 100 percent modulation
depth requires a microwave potential of 35 V to deplete the carriers completely in the active cladding region and negligible current, since the structure is capacitive.
This was related to the 100 percent modulation
depth and frequency of the dimming driver's pulse-width modulation output, but there are no published metrics to help the specifier identify in advance whether a product will exhibit flicker.
In this work, the detection efficiency is defined as the ratio of detected audio frequency power output to absorbed microwave power by the detector of rectangular wave modulated microwave signals with 100 percent modulation
of 50 percent duty cycle.