Water Vapor Sensors Based on the Swelling of Relief Gelatin Gratings

Figure 6

(a) and (b) show the behavior of first order intensity as a function of relative humidity (%) for two different gratings. In one of them optical delay in the grating was such that at about 25% RH first order intensity was a minimum (a). The opposite was true for the other grating (b).

(a)

(b)