Daniel Feldkhun

Doppler encoded excitation pattern tomographic optical microscopy

Most far-field optical imaging systems rely on lenses and spatially resolved detection to probe distinct locations on the object. We describe and demonstrate a high-speed wide-field approach to imaging that instead measures the complex spatial Fourier transform of the object by detecting its spatially integrated response to dynamic acousto-optically synthesized structured illumination. Tomographic filtered backprojection is applied to reconstruct the object in two or three dimensions. This technique decouples depth of field and working distance from resolution, in contrast to conventional imaging, and can be used to image biological and synthetic structures in fluoresced or scattered light employing coherent or broadband illumination. We discuss the electronically programmable transfer function of the optical system and its implications for imaging dynamic processes. We also explore wide-field fluorescence imaging in scattering media by coherence gating. Finally, we present two-dimensional high-resolution tomographic image reconstructions in both scattered and fluoresced light demonstrating a thousandfold improvement in the depth of field compared to conventional lens-based microscopy.

Single-shot afocal three-dimensional microscopy.

Fourier-basis agile structured illumination sensing (F-BASIS) employs acousto-optically synthesized moving interference patterns, sparse RF-encoded aperture synthesis, nonredundant spatiotemporal frequency multiplexing, and single-pixel detection to measure dense clouds of three-dimensional (3D) Fourier samples without scanning, enabling high-speed focus-free volume microscopy. We present 3D fluorescence imaging results using F-BASIS, including an unprecedented wide-field single-shot volumetric measurement in under 10 ms. The unique capabilities provided by F-BASIS could prove instrumental for capturing fleeting dynamic processes such as neuron signaling in 3D.

DEEP-dome: Towards Long-Working-Distance Aberration-Free Synthetic Aperture Microscopy

A DEEP microscope synthesizes images from dynamic structured-illumination Fourier measurements using a single-element detector, enabling high-resolution imaging with aberrated optics. We describe wide-field 20cm-working-distance DEEP microscopy using a large 0.4 NA diamond-turned reflector.

Afocal 3D Fluorescence Microscopy Using F-BASIS

F-BASIS 3D microscopy employs acousto-optically synthesized non-redundantly multiplexed moving interference patterns and RF detection to measure dense Fourier sample clouds, enabling high-speed focus-free volume microscopy. We present our first fluorescence imaging results.

Optical design and testing of a remote microscope

Microscopic imaging systems currently used on planetary exploration rovers operate over a short range, are dependent on ambient lighting and have a constrained depth of field requiring image stacking and increasing the data download requirement. The Structured Light Imaging Module Remote Microscope illuminates a target with acousto-optic generated traveling-wave sinusoidal patterns to measure the Fourier components of the object. It can resolve ~10 μm features at a distance of 5 meters with a ~20 mm depth of field enabling a rover to evaluate remote targets for further study. In this paper we present the optical and mechanical design, and initial characterization of the first to-scale SLIM-RM prototype.

Frequency-Mapped Focus-Free F-BASIS 3D Microscopy

F-BASIS 3D microscopy employs acousto-optically synthesized Doppler-encoded non-redundant interfering beam arrays, RF detection, and self-calibration to measure dense Fourier sample clouds simultaneously, enabling high-speed diffraction-limited volume imaging.

Multiplexed Agile Fourier Sampling for Doppler Encoded Excitation Pattern (DEEP) 3D Microscopy

A DEEP microscope synthesizes images from Fourier data measured using dynamic structured light and a single-element detector. We describe acousto-optic multiplexed pattern generation and Fourier sampling strategies for tomographic DEEP 3D imaging.

Fourier Analysis and Synthesis Tomography: Dynamic Measurement of 2D and 3D Structure

We present a full-field imaging technique that measures an object’s fluorescent or coherent spatial spectrum using projected dynamic interference patterns and a fast single-pixel detector, and reconstructs its 2D or 3D structure using tomographic algorithms.

Fourier Analysis and Synthesis Tomography: High-Resolution Long-Range Volume Imaging of Cells and Tissue

We present a light-efficient imaging technique that measures the sample’s fluorescent or coherent spatial spectrum using projected dynamic interference patterns, a fast single-pixel detector, and large low-precision optics, effectively decoupling depth-of-field and working-distance from resolution.