Pixel super-resolution in digital in-line holography

Abstract

We report a new holographic microscope using pixel super-resolution algorithm. In our method, a sequence of low resolution images are acquired by a complementary metal oxide semiconductor (CMOS) sensor in digital inline holography system and the resolution is limited by the sensor pixel size. Then the super-resolution algorithm is applied to the low resolution images to get the image with much higher resolution that beyond the Nyquist criteria. We perform both numerical simulation and experiments to demonstrate our method with US Air Force Target used as the sample. The sample is randomly moved in the sample plane and a set of holograms are captured by the camera in inline holographic system. We use two methods to reconstruct the sample image. In the first method, super-resolution algorithm is applied with the low resolution holograms to get the high resolution hologram. Then the high resolution hologram is reconstructed using auto-focusing algorithm to get the high resolution sample image. In the second method, the raw holograms are directly reconstructed to get a set of low resolution sample images, then the super-resolution algorithm is applied to get the high resolution sample image. We observed that the above mentioned two methods can get similar results in both numerical stimulation and experiments. We believe that the combination of pixel super-resolution algorithm and digital in-line holography can be very useful to implement a compact low-cost microscope with high resolution.