Continuous wave time of flight system

A time of flight, ToF, camera system comprising:

• a light emission unit;
• an image sensor configured to image light emitted from the light emission unit and reflected by an object to be imaged;
• and
• a controller coupled to the light emission unit and the image sensor, the controller being configured to:
• apply a modulated light control signal to the light emission unit for a first amount of time to cause the light emission unit to output modulated light for the first amount of time;
• control charge accumulation of the image sensor for a first portion of the first amount of time using a first modulated signal;
• and
• control charge accumulation of the image sensor for a second portion of the first amount of time using a second modulated signal,
• wherein the first modulated signal and the second modulated signal have different duty cycle ratios.

A system comprising:

• a light source;
• a controller coupled to the light source and configured to control the light source to emit modulated light for a first amount of time, wherein the controller is configured to:
• control the light source to emit light with a first modulation signal for a first portion of the first amount of time, the first modulation signal having a first duty cycle ratio;
• and
• control the light source to emit light with a second modulation signal for a second portion of the first amount of time, the second modulation signal having a second duty cycle ratio that is different to the first duty cycle ratio,
• wherein the duty cycle ratios of the first modulation signal and the second modulation signal are such that at least one harmonic in a combined signal formed by combining the first modulation signal and the second modulation signal has a lower amplitude than corresponding harmonic content in the first modulation signal and the second modulation signal.