About using Pockels cell for time-of-flight imaging

Time of Flight (ToF) imaging is one of the most used range image acquisition method. It is generally based on synchronous detection of a modulated light coming back from the target; this light being emitted by a controlled emitting device. Many commercial devices exist using ad hoc designed camera. One drawback is their low spatial resolution due to low resolution of the dedicated camera (typically 320x240). We propose to overcome this limitation by using a standard of the shelf camera. This can be achieved if the same light modulator is used both for direct and re‡ected light so that the light sensor has only to measure a mean intensity on a number of periods. Our proposition is based on Pockels cell modulator. A ToF imaging set-up based on it is designed and its performance are studied from a dedicated simulation software we have developed. The system we propose allows to extract a range image directly from the camera by computing the ratio of two successive images each one being shot with a known modulation frequency. The spatial resolution will be the same as the one of the camera and the imaging rate the half.