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Fluorescence lifetimes can be determined in the frequency domain by a phase-modulation method. The method uses a light source that is pulsed or modulated at high frequency (up to 500 MHz) such as an LED, diode laser or a continuous wave source combined with an electro-optic modulator or an acousto-optic modulator. The fluorescence is (a ...
Variations of red blood cell shape on blood film, overall termed poikilocytosis. Blood smear examination is usually performed in conjunction with a complete blood count in order to investigate abnormal results or confirm results that the automated analyzer has flagged as unreliable. [3]
The near-infrared (NIR) window (also known as optical window or therapeutic window) defines the range of wavelengths from 650 to 1350 nanometre (nm) where light has its maximum depth of penetration in tissue. [1] Within the NIR window, scattering is the most dominant light-tissue interaction, and therefore the propagating light becomes diffused ...
In addition to increasing with average illumination intensity, the fusion frequency also increases with the extent of modulation (the maximal relative decrease in light intensity presented); for each frequency and average illumination, there is a characteristic modulation threshold, below which the flicker cannot be detected, and for each ...
This classification goes in the increasing order of wavelength, which is characteristic of the type of radiation. [1] There are no precisely defined boundaries between the bands of the electromagnetic spectrum; rather they fade into each other like the bands in a rainbow. Radiation of each frequency and wavelength (or in each band) has a mix of ...
A photoplethysmogram (PPG) is an optically obtained plethysmogram that can be used to detect blood volume changes in the microvascular bed of tissue. [1] [2] A PPG is often obtained by using a pulse oximeter which illuminates the skin and measures changes in light absorption. [3]
In other words, the immune system must be exposed to the antigen in order to illicit antibody production. Exposure to antigens can occur through blood transfusion, stem cell/bone marrow transplant, and pregnancy. [4] The clinical significance of an alloantibody depends on its ability to cause a decrease in donor red blood cell survival. [12]
A white beam source – emitting light of multiple wavelengths – is focused on a sample (the complementary color pairs are indicated by the yellow dotted lines). Upon striking the sample, photons that match the energy gap of the molecules present (green light in this example) are absorbed in order to excite the molecule.