By measuring the energy received in successive integration intervals, it is possible to
extrapolate the distance between the sensor and the measured object, based on the
ratio of energy received in the different intervals.
The difficulty with range-gated imaging is that CCD and CMOS imagers have a limited
dynamic range; therefore, strong ambient light can easily cause saturation and impair
measurement. Furthermore, since neither the emitted and received pulses are perfect
rectangle pulses, nor is the sensor perfectly linear, compensation is required and
accuracy is ultimately limited.
5.1.3 Continuous Waveform ToF
In contrast to the previous two methods, phase difference measurement relies on a
modulated light source and evaluates the phase difference between the transmit signal
and the receive echo. This phase difference can be converted to a distance, using the
following formula:
