Continuous wave time of flight system

A method of obtaining a plurality of charge samples using a continuous wave time of flight ToF, CW-ToF, camera system comprising a laser and an imaging sensor having a plurality of imaging pixels for accumulating charge based on incident light, the method comprising:

• acquiring a first set of charge samples from the imaging sensor while operating in a low energy mode by:
• a) driving the laser to output laser light modulated with a first modulation signal, wherein the first modulation signal has a first frequency;
• and
• b) reading out image sensor values indicative of charge accumulated by at least some of the plurality of imaging pixels of the image sensor;
• acquiring a second set of charge samples from the imaging sensor while operating in a high energy mode by:
• c) driving the laser to output laser light modulated with a second modulation signal, wherein the second modulation signal has a second frequency, and wherein the second frequency is greater than the first frequency;
• and
• d) reading out image sensor values indicative of charge accumulated by at least some of the plurality of imaging pixels of from the image sensor that is greater than the plurality of imaging pixels read out while operating in the lower energy mode.

An image acquisition system for use in a continuous wave time of flight, CW-ToF, camera system, the image acquisition system being configured to:

• obtain, while operating in a low energy mode, a first plurality of charge samples by being configured to:
• drive a laser to emit first laser light modulated with a first modulation signal using a relatively low energy mode;
• and
• read out image sensor values from a first plurality of imaging pixels of an imaging sensor;
• obtain, while operating in a high energy mode, the second plurality of charge samples by being configured to:
• drive the laser to emit second laser light modulated with a second modulation signal using a second energy mode;
• and
• read out image sensor values from a second plurality of imaging pixels of the imaging sensor,
• wherein each of the first plurality of charge samples comprises fewer data points obtained during the low energy mode compared with each of the second plurality of charge samples obtained during the high energy mode.