Optical tracking device and a method of operation thereof

An optical tracking device comprising:

• a light source configured to emit light towards a surface;
• an image sensor configured to receive light reflected from the surface;
• a processing unit configured to:
• instruct a light source driving unit to drive the light source to generate light at regular first intervals of a first frequency forming a sequence of synchronisation flashes, each synchronisation flash having a first predetermined duration;instruct an image sensor controlling unit to determine image arrays from the light received by the image sensor at the regular first intervals, the first image arrays comprising a first plurality of pixels;instruct a comparator unit to generate a first comparison array between the first image arrays generated at subsequent first intervals;determine a first displacement amount based on the first comparison array;
• wherein, if the first displacement amount is bigger than a displacement amount threshold, the processing unit is further configured to:
• instruct the light source driving unit to drive the light source to generate light at regular second intervals of a second frequency forming at least a regular flash with a second predetermined duration;
• the first predetermined duration being shorter than the second predetermined duration;
• instruct the image sensor controlling unit to determine second image arrays from the light received by the image sensor at the regular second intervals, the second image arrays comprising a second plurality of pixels;
• instruct a comparator unit to generate a second comparison array between the second image arrays generated at subsequent second intervals;
• determining a second displacement amount based on the second comparison array.