To map the change in hemoglobin concentration, it is necessary to know where the data are taken
The red points in the figure (below) illustrate the positions of illuminated points, and the blue points show detected points. These points are arranged in a grid 30mm square. The point midway between an illuminated point and a detected point is defined as a measured point. The measured points detect both the oxy- and deoxy-hemoglobin change the way already shown in column and denoted here by a small square with number, each of whose positions is decided by the fiber's position.
If we prepare 8 points of illumination and 8 points of detection, there are a total of 24 measuring points and from the data, a map is shown on the monitor using digital interpolation technique.
