Line imaging of fluorescent and absorptive objects with a single-pixel imaging technique that acquires one-dimensional cross-sections through a sample by imposing a spatially-varying amplitude modulation on the probing beam is demonstrated. The fluorophore concentration or absorber distribution of the sample is directly mapped to modulation frequency components of the spatially-integrated temporal signal. Time-domain signals are obtained from a single photodiode, with object spatial frequency correlation encoded in time-domain bursts in the electronic signal from the photodiode.

Fluorescent imaging plays a critical role in a myriad of scientific endeavors, particularly in the biological sciences. Three-dimensional imaging of fluorescent intensity often requires serial data acquisition, that is, voxel-by-voxel collection of fluorescent light emitted throughout the specimen with a nonimaging single-element detector. While nonimaging fluorescence detection offers some measure of scattering robustness, the rate at which dynamic specimens can be imaged is severely limited. Other fluorescent imaging techniques utilize imaging detection to enhance collection rates. A notable example is light-sheet fluorescence microscopy, also known as selective-plane illumination microscopy, which illuminates a large region within the specimen and collects emitted fluorescent light at an angle either perpendicular or oblique to the illumination light sheet. Unfortunately, scattering of the emitted fluorescent light can cause blurring of the collected images in highly turbid biological media. We recently introduced an imaging technique called coherent holographic image reconstruction by phase transfer (CHIRPT) that combines light-sheet-like illumination with nonimaging fluorescent light detection. By combining the speed of light-sheet illumination with the scattering robustness of nonimaging detection, CHIRPT is poised to have a dramatic impact on biological imaging, particularly for in vivo preparations. Here we present the mathematical formalism for CHIRPT imaging under spatially coherent illumination and present experimental data that verifies the theoretical model.

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Abstract:We describe a system for automated modelocking and optimization of a fiber laser oscillator employing nonlinear polarization evolution. Using four liquid crystal variable retarders, we fully control the fiber launch and output polarization states, enabling compensation for mechanical and environmental perturbations to the fiber cavity. We demonstrate mapping of the modelocking regions for an ANDi fiber oscillator and demonstrate that local and global optimization algorithms can be used to maintain the laser in the same operating state. This technique enables robust operation of nonlinear polarization evolution modelocked fiber lasers, rivaling the stability of PM fiber lasers while maintaining the advantages of the NPE modelocking mechanism. 694-696 (1999). 12. M. Nikodem, K. Krzempek, K. Zygadlo, G. Dudzik, A. Waz, K. Abramski, and K. Komorowska, "Intracavity polarization control in mode-locked Er-doped fibre lasers using liquid crystals," Opto-Electron. Rev.

Four images of Drosophila Melanogaster antennal lobe structure labeled with red fluorescent protein. The images are separated axially by 7 μm in depth, and were all acquired simultaneously from a single-element detector.