We present a high-resolution, wide-field of view (FOV) computational microscope that employs an array of image sensors with gaps between them and a diffractive optical element (DOE) in the Fourier plane. The sensor array consists of a 6 x 8 array of 13-megapixel sensors (total ~0.6 gigapixels), spanning a 5 cm by 6.6 cm region with a ~22% fill factor. To fill in the inter-sensor gaps without scanning, we introduce a DOE at the pupil that generates a distributed PSF, allowing us to multiplex information from the missing ~78% of the total area into the sensing regions. Our large-scale reconstruction algorithm demixes the superimposed information, resulting in a >4x expanded FOV. Our approach can enable multi-gigapixel imaging in a single snapshot.
In imaging system design, computational applications and optical components are interdependent. End-to-end optimization, jointly optimizing hardware and software, is a prevalent approach. However, most optical simulators use ray optic models, which may lack real-world fidelity. We propose a differentiable wave optics model that accurately simulates light propagation. It exposes performance disparities among physical models. Integrated with unrolled FISTA and color filters, the system consistently yields clear measurements and accurate recovery. By noting the performance degradation caused by deviations from real-world physics, our wave optics model is a superior choice for end-to-end imaging system design.
KEYWORDS: 3D scanning, Micromirrors, Mirrors, Monte Carlo methods, Lenses, Optical scanning, Microelectromechanical systems, Actuators, Diffraction, 3D acquisition
Rapid 3D optical scanning of points or patterned light is widely employed across applications in microscopy, material processing, adaptive optics and surveying. Despite this broadness in applicability, embodiments of 3D scanning tools may vary considerably as a result of the specific performance needs of each application. We present here a micromirror arraybased modular framework for the systemic design of such high-speed scanning tools. Our framework combines a semicustom commercial fabrication process with a comprehensive simulation pipeline in order to optimally reconfigure pixel wiring schemes across specific applications for the efficient allocation of available degrees of freedom. As a demonstration of this framework and to address existing bottlenecks in axial focusing, we produced a 32-ring concentric micromirror array capable of performing random-access focusing for wavelengths of up to 1040 nm at a response rate of 8.75 kHz. By partitioning the rings into electrostatically driven piston-mode pixels, we are able to operate the array through simple openloop 30 V drive, minimizing insertion complexity, and to ensure stable operation by preventing torsional failure and curling from stress. Furthermore, by taking advantage of phase-wrapping and the 32 degrees of freedom afforded by the number of independently addressable rings, we achieve good axial resolvability across the tool’s operating range with an axial fullwidth- half-maximum to range ratio of 3.5% as well as the ability to address focus depth-dependent aberrations resulting from the optical system or sample under study.
Biologists use optical microscopes to study plankton in the lab, but their size, complexity and cost makes widespread deployment of microscopes in lakes and oceans challenging. Monitoring the morphology, behavior and distribution of plankton in situ is essential as they are excellent indicators of marine environment health and provide a majority of Earth’s oxygen and carbon sequestration. Direct in-line holographic microscopy (DIHM) eliminates many of these obstacles, but image reconstruction is computationally intensive and produces monochromatic images. By using one laser and one white LED, it is possible to obtain the 3D location plankton by triangulation, limiting holographic reconstruction to only the voxels occupied by the plankton, reducing computation by several orders of magnitude. The color information from the white LED assists in the classification of plankton, as phytoplankton contains green-colored chlorophyll. The reconstructed plankton images are rendered in a 3D interactive environment, viewable from a browser, providing the user the experience of observing plankton from inside a drop of water.
We present a simple technique which uses a random phase object for single-shot characterization of an optical system's phase transfer function. Existing methods for aberration measurement typically involve holography, requiring complicated wavefront sensing optics or through-focus measurements with known test objects (e.g. pinholes, fluorescent beads) for pupil recovery from the measured wavefront. Here, it is demonstrated that a weak diffuser can be used to recover the pupil of an imaging system in a single measurement, without exact knowledge of the diffuser's surface. Due to its stochastic nature, the diffuser scatters light to a wide range of spatial frequencies, thus probing the entire pupil plane. A linear theory based on the weak object approximations predicts the spectrum of the measured speckle intensity to depend directly on the pupil function. Numerical simulations of diffusers with varying strength confirm the validity of the theory and indicate sufficient conditions under which diffusers act as weak phase objects. Using index matching oils to modulate diffuser strength, experiments are shown to successfully recover aberrations from an optical system using coherent illumination. Additionally, this technique is applied to the recovery of defocus in images of a weak phase object obtained through a commercial microscope under partially coherent illumination.
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