An experimenter performs a RICS experiment using a mixture (mixture 1:1 of monomers and tetramers, with a total concentration of 2nM. The instrument has a pixel size of 50nm, the total number of pixels in a line is 256 and there are 256 lines. The pixel dwell time is 2microseconds. Assume no retracing time. The beam wait in radial direction is 300 nm and in the axial direction is 5 times larger. What is the measured amplitude of the RICS correlation function

Raster Image Correlation Spectroscopy (RICS) is a novel new technique for measuring molecular dynamics and confocal fluorescence imaging concentrations. RICS technique extracts information on molecular dynamics and concentrations of live cell images taken in commercial confocal systems

Explanation:

RICS analysis must be performed on images acquired through raster scanning. Laser scanning microscopes generate images by measuring the fluorescence intensity in one area of a pixel at a time (a 'pixel' in this context does not have the same definition as a pixel in computer graphics, but refers to a measurement of localized intensity). The value of a pixel is obtained by illuminating a region of the sample with the focal volume of a laser beam and measuring the intensity of the fluorescence emitted. The laser beam moves to a new location and a new pixel is recorded. Each pixel can be considered to correspond to a region of the sample, with its width (called pixel size) defined by the distance the beam moves between measurements. This means that the size of a pixel is separate and independent from the size of the focal volume of the laser beam.