[5.9.9.8] As pertaining to temporal light modulation: The Michelson contrast of the varying waveform in a single cycle, calculated as (L_max – L_min) / (L_max + L_min), and expressed as a percentage, where L_max is the maximum and L_min is the minimum output during a single cycle.
(See left-hand graphic in Figure 5-2.)

Also known as percent flicker, modulation %, modulation depth, or peak-to-peak contrast.

Note: Percent modulation accounts for the peak-to-peak amplitude of the waveform, but it does not account for wave shape, duty cycle, or modulation frequency.

Figure 5-2. A periodic temporal light modulation (TLM) waveform illustrating period, and values critical for calculating percent flicker (left) and flicker index (right). The waveform repeats itself every 0.01 second, thus exhibiting a fundamental frequency of 100 Hz, and it has a sinusoidal modulation 3 times per period, indicating a secondary frequency of 300 Hz. (Graphic courtesy of Pacific Northwest National Laboratory) (Note: Identical to Figure 5-1.)

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