Imaging modalities such as optical coherence tomography (OCT) and ultrasound-modulated optical tomography (UOT) can be used to generate images of a target region in highly-scattering media. For example, OCT and UOT can be used for non-invasive imaging of tissue regions below a skin surface. However, because biological tissue is a highly-scattering medium, the signal-to-noise ratio is fairly poor and limits the resolution of images acquired using OCT or UOT. Changes in the optical properties of the target region that occur during the acquisition time window may result in image blur and/or information loss, for example due to decorrelation of the speckle interference pattern which is to be measured in these techniques. For example, changes in tissue blood perfusion and/or neural activity can occur rapidly, decorrelating or otherwise corrupting UOT or OCT measurements, or other interference based or holographic measurements, if the measurements occur on a slower timescale than the tissue decorrelation.
An imager having a very rapid image data acquisition rate (e.g., frame rate) compared to the decorrelation timescale can help improve the signal quality for OCT or UOT or other interference based or holographic measurement techniques in rapidly decorrelating turbid media. One example of an imager potentially having a sufficiently fast frame rate is a lock-in camera, which is able to acquire multiple measurements of a light field rapidly at each detector pixel in a temporally precise fashion synchronized with an external trigger or oscillation, storing the multiple measurements in multiple electronic charge storage “bins” within each pixel. Phase shifting holography operations using lock-in cameras can help improve the resolution and signal quality of low-coherence interferometry or UOT imaging. However, lock-in camera sensors often lack features that are common in high-performance conventional imager sensors. For example, lock-in camera sensors currently have a lower pixel count and electron well-depth as compared to conventional imager sensors. Other optical arrangements that simulate the rapid data acquisition rate of lock-in cameras in the context of spatially resolved holographic wavefront measurements use two or more imagers with precise pixel-level alignment and matched optical path lengths. One example of such optical arrangement is an imager system comprising a plurality of separate imagers that are optically aligned with each other, such that any given pixel(s) on the imagers have a known one-to-one correspondence with each other (OLIC configuration). However, the use of multiple precisely aligned imagers can be cumbersome and prone to alignment errors. Accordingly, improvements to imagers for high-speed, high pixel-count image data acquisition are desirable.
USPTO Backgrounds
USPTO Backgrounds