Photon-counting Detectors
Photon-counting Detectors - Related Videos
12:19
Measurement of Quantum Interference in a Silicon Ring Resonator Photon Source
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Cited by 2 •
2017
Silicon photonic chips have the potential to realize complex integrated quantum systems. Presented here is a method for preparing and testing a silicon photonic chip for quantum measurements.
10:19
Using a Hemacytometer to Count Cells
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2023
Many biomedical experiments require manipulation of a known quantity of cells, in order to achieve accurate, reproducible, and statistically-relevant data. Therefore, learning how to count cells is a particularly essential technique for any successful biomedical scientist. The most common way to count cells is by using a hemacytometer - an instrument that bears two laser-etched grids, which aid in the enumeration of an aliquot cells under a simple light microscope. This data can then be used to...
05:47
Counting and Determining the Viability of Cultured Cells
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Cited by 19 •
2008
Determining the number of cells in culture is important in standardization of culture conditions and in performing accurate quantitation experiments. In this video, we demonstrate how cells are counted using a hemacytometer.
01:13
Gas Chromatography: Overview of Detectors
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2025
Detectors in gas chromatography (GC) help identify and quantify the components of a mixture by translating chemical properties into measurable signals, which are displayed on a chromatogram. Detectors can be categorized into two main types: destructive and non-destructive. A non-destructive detector allows a sample to be analyzed without altering or consuming it, meaning the sample can be collected after detection for further analysis. Examples include thermal conductivity detectors and...
01:19
Gas Chromatography: Types of Detectors-II
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2024
In gas chromatography, different detectors are employed to meet specific analytical needs. These detectors are often categorized based on their detection mechanisms and the types of compounds they are best suited to analyze. Thermal Conductivity Detectors (TCD), Flame Ionization Detectors (FID), and Electron Capture Detectors (ECD) represent common categories, each with unique operating principles and applications. However, beyond these, several other detectors are designed for more specialized...
FAQs
Each detected photon produces an electrical pulse that can be counted or assigned a time stamp. The resulting event record supports two complementary measurements: total counts estimate signal intensity, while arrival times reveal temporal structure. This event-based approach allows weak biological signals to be quantified without relying only on a continuously varying output.
Optical filters help isolate the wavelengths associated with the signal of interest, reducing interference from other light. Time-correlated electronics then record photon events in relation to their arrival times, allowing rapid events and fluorescence lifetimes to be resolved. Together, these components connect spectral selectivity with precise temporal measurement in biological experiments.
Signal intensity reflects how many photons are detected, but the timing of those events provides additional information about the process producing the light. Photon arrival patterns can expose rapid changes, whereas fluorescence-lifetime measurements describe how long fluorescence persists. These complementary readouts help investigators examine dynamic biological processes rather than only comparing brightness.
In fluorescence microscopy, the detector is paired with optical filtering to select the relevant wavelengths and may be connected to time-correlated electronics when timing information is needed. The system records photon counts, arrival patterns, or fluorescence lifetimes from the specimen. This arrangement supports sensitive observation of cellular components and molecular interactions producing very weak fluorescence.
Applications include fluorescence microscopy, flow cytometry, luminescence assays, and single-molecule studies. Depending on the instrument configuration, measurements can emphasize signal intensity, photon arrival patterns, or fluorescence lifetimes. These readouts help quantify cellular components, characterize molecular interactions, and follow dynamic processes that may produce only extremely weak optical signals.
Photomultiplier tubes and avalanche photodiodes are common detector implementations for registering individual photons. Their use allows biological instruments to translate weak optical events into electrical pulses suitable for counting or timing. When combined with wavelength-selective filters and time-correlated electronics, they support sensitive measurements across microscopy, cytometry, luminescence, and single-molecule experiments.