Optical phase conjugation is a technique that could find many applications in medical imaging and industry. However, state of the art techniques are limited in speed, portability and efficiency. Especially for digital optical phase conjugation, the electronic delays for image readout on a camera and addressing a spatial light modulator make this technique unpractical for phase conjugation in biological medium. Furthermore, the calibration of such a system is a very complex and expensive task. Thus, we propose integrating on the same device a camera and a liquid crystals spatial light modulator to achieve phase control thanks to in-pixel processing of a photodiode signal.
We present a CMOS light detector-actuator array, in which every pixel combines a spatial light modulator and a photodiode. It will be used in medical imaging based on acousto-optical coherence tomography with a digital holographic detection scheme. Our architecture is able to measure an interference pattern between a scattered beam transmitted through a scattering media and a reference beam. The array of 16 μm pixels pitch has a frame rate of several kfps, which makes this sensor compliant with the correlation time of light in biological tissues. In-pixel analog processing of the interference pattern allows controlling the polarization of a stacked light modulator and thus, to control the phase of the reflected beam. This reflected beam can then be focused on a region of interest, i.e. for therapy. The stacking of a photosensitive element with a spatial light modulator on the same chip brings a significant robustness over the state of the art such as perfect optical matching and reduced delay in controlling light.
In a context of embedded video surveillance, stand alone leftbehind image sensors are used to detect events with
high level of confidence, but also with a very low power consumption. Using a steady camera, motion detection
algorithms based on background estimation to find regions in movement are simple to implement and computationally
efficient. To reduce power consumption, the background is estimated using a down sampled image formed
of macropixels. In order to extend the class of moving objects to be detected, we propose an original mixed
mode architecture developed thanks to an algorithm architecture co-design methodology. This programmable
architecture is composed of a vector of SIMD processors. A basic RISC architecture was optimized in order to
implement motion detection algorithms with a dedicated set of 42 instructions. Definition of delta modulation as
a calculation primitive has allowed to implement algorithms in a very compact way. Thereby, a 1920x1080@25fps
CMOS image sensor performing integrated motion detection is proposed with a power estimation of 1.8 mW.