A laser can be classified as operating in either continuous or pulsed mode, depending on whether the power output is essentially continuous over time or whether its output takes the form of pulses of light on one or another time scale. (Figure 1)
Continuous Wave
Modulated Continuous Wave
Q Switched (nanosecond pulses)
Long pulsed (micro or millisecond pulses)
Graph A:Continuous wave (CW) is like a light that is constantly “on”
Graph B and C:Modulated lasers produce light that is “on” half the time and “off” half the time. The duty cycle is simply 50 percent, because the light is “on” half the time and “off” half the time.
An advanced definition of duty cycle is the duration of the pulse divided by the period, or the time from the beginning of one pulse to the beginning of the next.
Graph D: The laser represented has a duty cycle of 25 percent; it is “on” one-fourth of the time and “off” three-fourths of the time.
Graph B and C:Modulated lasers produce light that is “on” half the time and “off” half the time. The duty cycle is simply 50 percent, because the light is “on” half the time and “off” half the time.
An advanced definition of duty cycle is the duration of the pulse divided by the period, or the time from the beginning of one pulse to the beginning of the next.
Graph D: The laser represented has a duty cycle of 25 percent; it is “on” one-fourth of the time and “off” three-fourths of the time.
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