Low-Light Imaging In SWIR With Homodyne Detection

Although uses for low-light imaging are numerous, they are only available in the visible spectrum, where detector noise performance is optimal. Although the camera’s noise floor is about 200 times higher, researchers demonstrated a full-field, homodyne imaging device that can image at the single-photon level in the shortwave infrared. Gabor first proposed this interference method of low-light photography 70 years ago. In contrast to other temporally based interference methods, which call for temporal scanning, the strategy only needs one camera frame. The display will increase the functionality of holographic microscopes and broaden the uses for low-light imaging, which will help with biological, medical, and covert imaging.

In conditions where low-noise detectors are not yet accessible, low-light imaging is difficult. One such regime is the shortwave infrared, where the noise floor is usually greater than 100 photons per pixel per frame, even for the best multipixel detector arrays. Despite an illumination intensity of 1 photon per pixel, researchers have demonstrated a homodyne imaging device that can recover an object’s intensity and phase images from a single frame.

By gaining access to areas where low-noise cameras are currently unavailable, and low-intensity illumination is required, researchers think their method could significantly expand the range of applications for low-light imaging.

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