Real time calibration for time-of-flight depth measurement

In a digital camera characterized by a preset frame rate, a method comprising:

• in a single frame period,
• transmitting light pulses to illuminate a target object;
• sensing, in a first region of a light-sensitive pixel array, light provided from an optical feedback device that receives a portion of the transmitted light pulses, the feedback optical device including a preset reference depth, wherein the light from the optical feedback device is sampled using a sequence of shutter windows that includes delay times representing a range of distance;
• calibrating time-of-flight (TOF) depth measurement reference information based on the sensed light in the first region of the pixel array;
• sensing, in a second region of the light-sensitive pixel array, light reflected from the target object from the transmitted light pulses;
• and
• determining a distance of the target object based on the sensed reflected light and the calibrated TOF measurement reference information.

A method for calibrating a time-of-flight (TOF) camera system, comprising:

• transmitting light pulses to illuminate a target object for determining a distance to the target object;
• sensing, in a first region of a light-sensitive pixel array, light provided from a feedback optic device that receives a portion of the transmitted light pulses, the feedback optical device including a preset reference depth;
• sensing, in a second region of the light-sensitive pixel array, light reflected from the target object from the transmitted light pulses, using a sequence of shutter windows that includes delay times representing a range of depth;
• calibrating time-of-flight depth measurement information based on the light provided from the feedback optical device;
• and
• determining the distance of the target object based on light reflected from the target object and the calibrated time-of-flight depth measurement information.