Absolute measurement of quantum efficiency of photon-counting photomultiplier using quantum two-photon field and a ratio between single- and double-electron peaks

1999 ◽  
Author(s):  
Aladar Czitrovszky ◽  
Alexander V. Sergienko ◽  
Peter Jani ◽  
Attila Nagy
Keyword(s):  
Quantum Efficiency ◽  
Photon Counting ◽  
Absolute Measurement ◽  
Two Photon ◽  
Photon Field ◽  
Double Electron

scholarly journals COMPARATIVE TEST OF TWO METHODS OF QUANTUM EFFICIENCY ABSOLUTE MEASUREMENT BASED ON SQUEEZED VACUUM DIRECT DETECTION

2011 ◽  
Vol 09 (supp01) ◽  
pp. 251-262 ◽  
Author(s):  
I. N. AGAFONOV ◽  
M. V. CHEKHOVA ◽  
A. N. PENIN ◽  
G. O. RYTIKOV ◽  
O. A. SHUMILKINA ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Direct Detection ◽  
Photon Counting ◽  
Absolute Measurement ◽  
High Gain ◽  
New Method ◽  
Absolute Calibration ◽  
Squeezed Vacuum ◽  
The Difference ◽  
Absolute Quantum

We realize and test in experiment a method recently proposed for measuring absolute quantum efficiency of analog photodetectors. Similar to the traditional (Klyshko) method of absolute calibration, the new one is based on the direct detection of two-mode squeezed vacuum at the output of a traveling wave OPA. However, in the new method, one measures the difference-photocurrent variance rather than the correlation function of photocurrents (number of coincidences), which makes the technique applicable for high-gain OPA. In this work we test the new method versus the traditional one for the case of photon-counting detectors where both techniques are valid.

scholarly journals Optical Estimation of Absolute Membrane Potential Using One- and Two-Photon Fluorescence Lifetime Imaging Microscopy

2021 ◽  
Author(s):  
Julia R. Lazzari-Dean ◽  
Evan W. Miller
Keyword(s):  
Membrane Potential ◽  
Fluorescence Lifetime ◽  
Single Photon ◽  
Photon Counting ◽  
Fluorescence Lifetime Imaging ◽  
Single Photon Counting ◽  
Two Photon ◽  
Lifetime Imaging ◽  
Wide Range ◽  
Relative Measurements

AbstractBackgroundMembrane potential (Vmem) exerts physiological influence across a wide range of time and space scales. To study Vmem in these diverse contexts, it is essential to accurately record absolute values of Vmem, rather than solely relative measurements.Materials & MethodsWe use fluorescence lifetime imaging of a small molecule voltage sensitive dye (VF2.1.Cl) to estimate mV values of absolute membrane potential.ResultsWe test the consistency of VF2.1.Cl lifetime measurements performed on different single photon counting instruments and find that they are in striking agreement (differences of <0.5 ps/mV in the slope and <50 ps in the y-intercept). We also demonstrate that VF2.1.Cl lifetime reports absolute Vmem under two-photon (2P) illumination with better than 20 mV of Vmem resolution, a nearly 10-fold improvement over other lifetime-based methods.ConclusionsWe demonstrate that VF-FLIM is a robust and portable metric for Vmem across imaging platforms and under both one-photon and two-photon illumination. This work is a critical foundation for application of VF-FLIM to record absolute membrane potential signals in thick tissue.

scholarly journals Absolute measurement of molecular two-photon absorption cross-sections using a fluorescence saturation technique

2006 ◽  
Vol 14 (18) ◽  
pp. 8434 ◽  
Author(s):  
Martin Kauert ◽  
Patrick C. Stoller ◽  
Martin Frenz ◽  
Jaro Ri?ka
Keyword(s):  
Cross Sections ◽  
Absolute Measurement ◽  
Photon Absorption ◽  
Absorption Cross ◽  
Two Photon Absorption ◽  
Two Photon

A custom confocal and two-photon digital laser scanning microscope

2000 ◽  
Vol 278 (6) ◽  
pp. H2150-H2156 ◽  
Author(s):  
W. Gil Wier ◽  
C. William Balke ◽  
Jeffrey A. Michael ◽  
Joseph R. H. Mauban
Keyword(s):  
Laser Scanning ◽  
Photon Counting ◽  
Objective Lens ◽  
Scanning Microscope ◽  
Fluorescence Detector ◽  
Laser Scanning Microscope ◽  
Ti:Sapphire Laser ◽  
Two Photon ◽  
Photon Excitation ◽  
Two Photon Excitation

We describe a custom one-photon (confocal) and two-photon all-digital (photon counting) laser scanning microscope. The confocal component uses two avalanche photodiodes (APDs) as the fluorescence detector to achieve high sensitivity and to overcome the limited photon counting rate of a single APD (∼5 MHz). The confocal component is approximately nine times more efficient than our commercial confocal microscope (fluorophore fluo 4). Switching from one-photon to two-photon excitation mode (Ti:sapphire laser) is accomplished by moving a single mirror beneath the objective lens. The pulse from the Ti:sapphire laser is 109 fs in duration at the specimen plane, and average power is ∼5 mW. Two-photon excited fluorescence is detected by a fast photomultiplier tube. With a ×63 1.4 NA oil-immersion objective, the resolution of the confocal system is 0.25 μm laterally and 0.52 μm axially. For the two-photon system, the corresponding values are 0.28 and 0.82 μm. The system is advantageous when excitation intensity must be limited, when fluorescence is low, or when thick, scattering specimens are being studied (with two-photon excitation).

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