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Tag Archives: Scanning
Why your two-photon images are noisier than you expect
A gallery of calcium imaging recordings of neurons and astrocytes with single noisy frames on the left and averaged beautiful noise-free images on the right side. Continue reading
Posted in Calcium Imaging, Data analysis, hippocampus, Imaging, Microscopy, Neuronal activity, neuroscience, zebrafish
Tagged Calcium Imaging, Data analysis, Microscopy, photons, Scanning, zebrafish
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Improving the resonant scanner’s sync signal using a phase locked loop (PLL)
Calcium imaging with two-photon point scanning is the technique to chronically record from identified neurons in the living brain of animals. The central piece of two-photon point scanning microscopes is a scan engine. This can be a complex optical device … Continue reading
Posted in Calcium Imaging, Imaging, Microscopy, neuroscience
Tagged Microscopy, photons, Scanning
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Interesting papers on online motion correction for calcium imaging
In a living animal, the brain is moving up and down in the skull. This brain motion can be due to breathing, heartbeat, tongue movements, but also due to changes of posture or running. For each brain region and posture, … Continue reading
Posted in Calcium Imaging, Data analysis, Imaging, machine learning, Microscopy, Neuronal activity, neuroscience
Tagged Calcium Imaging, Data analysis, Microscopy, photons, Scanning
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“Laser Scanners” by William Benner
William Benner is a scanner enthusiast and the president of the company Pangolin. His company sells equipment mostly for laser shows but also for other applications. Some years ago, he wrote a book on “Laser Scanners”, which is available through … Continue reading
Simple geometrical optics to understand and design point-scanning microscopes
Custom-built microscopes have become more and more sophisticated over the last years to provide a larger FOV, better resolution through some flavor of adaptive optics or simply more neurons simultaneously. Professional optical engineers are hired to design the ideal lens … Continue reading
Large-scale calcium imaging & noise levels
Calcium imaging based on two-photon scanning microscopy is a standard method to record the activity of neurons in the living brain. Due to the point-scanning approach, sampling speed is limited and the dwell time on a single neuron reduces with … Continue reading
Posted in Calcium Imaging, Data analysis, Imaging, Microscopy, Neuronal activity
Tagged Calcium Imaging, Data analysis, Microscopy, photons, Scanning
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Fast scanning, triplet states and photon yield
In point-scanning microscopy like two-photon or confocal microscopy, a focused laser beam is scanned across the field of view and thereby sequentially recovers an image of the object. In this blog post, I will discuss the idea that scanning faster … Continue reading
Posted in Calcium Imaging, Imaging, Microscopy, Neuronal activity
Tagged Calcium Imaging, Microscopy, photons, Scanning, zebrafish
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Review: An artificial ground truth for calcium imaging
Selected paper: Charles, Song, Tank et al., Neural Anatomy and Optical Microscopy Simulation (NAOMi) for evaluating calcium imaging methods, bioRxiv (2019). What is the paper about? Calcium imaging is a central method to observe neuronal activity in the brain of … Continue reading
Posted in Calcium Imaging, Data analysis, Imaging, Microscopy, Neuronal activity, Reviews
Tagged Data analysis, Microscopy, photons, PSF, Scanning
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Photon yield and pulse dispersion
This case report describes how a two-photon microscope was found to come with a fluorescence yield that was lower than expected; how the underlying cause was found out in a systematic manner; and how the problem was solved. All approaches and solutions are specific for the microscope under question. However, I hope that this report (1) will inspire other people who are troubleshooting or optimizing their microscopes, (2) will help other people better understand two-photon microscopes and the relevance of technical details. Continue reading
Alvarez lenses and other strangely shaped optical elements
In typical microscopes, lenses or mirrors are moved forth and back to change the position of their focus. Tunable lenses like the electro-tunable lens or the TAG lens, on the other hand, are deformed by an external force and thereby … Continue reading
A blog about neurophysiology 