Light scatter forward

Haze characterizes the loss of contrast that results when objects are viewed through a scattering mediiun. The deterioration of contrast is due mainly to light scattered forward at large angles to the undeviated transmitted beam and is usually expressed through the forward-scattered fraction. 

The flow cytometer, fitted with both forward and side scatter detectors, generates a 2D plot indicating the distribution of light intensity, forward scatter (FS) versus side scatter (SS), and showing the physical profile of the particle responsible for the scatter. Figure 5.3 is such a plot for a mixture of five rod-shaped bacteria from our laboratory. The different strains appear in partly separated clusters (indicated by square boxes and dot color) along the side-scatter axis in the lower part of the plot. 

In the large off-axis light scatter detection method, the droplet size can be related, for example, to the phase shift of the light scattered by refraction in the off-axis forward direction as ... 

Ormerod MG, Cheetham FPM, Sun X-M. 1995. Discrimination of apoptotic thymocytes by forward light scatter. Cytometry 21 300-304. 

Fig. 2. Forward vs right-angle light-scatter profiles of granulocytes in an erythrocyte-lysed, whole-blood sample (A) and a purified granulocyte preparation (B).

Adjust the forward aud right-augle light-scatter detectors so that the granulocyte population is clearly visible (see Chapter 32, Subheading 3.5.3., Fig. 2). 

Figure 2. Repr3sentation of measurement of multiple parameters of single cells via flow cytometer fluorescence analysis and sorting. IGF= Integrated green fluorescence. IRF= Integrated red fluorescence. FALS= Forward angle light scatter.

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