Fig. 2: Experimental demonstration of focal stack imaging using double stacks of graphene detector arrays.
From: Neural network based 3D tracking with a graphene transparent focal stack imaging system
a A schematic of measurement setup. A point object (dotted circle) is generated by focusing a green laser beam (532 nm) with the lens. Its position is controlled by a 3D motorized stage. Two detector arrays (blue sheets) are placed behind the lens. An objective and CMOS camera are placed behind the detector array for sample alignment. A chopper modulates the light at 500 Hz and a lock-in amplifier records the AC current at the chopper frequency. b Images captured by the front and back photodetector planes with objects at three different positions along the optical axis (12 mm, 18 mm, 22 mm, respectively). The grayscale images are generated using responsivities for individual pixels within the array, normalized by the maximum value for better contrast. The point source is slightly off-axis in the image presented, leading to the shift of spot center. c The illustrations of the beam profiles corresponding to the imaging planes in (b). The focus is shifting from the back plane (top panel) toward the front plane (bottom panel).
