ABSTRACT
To calculate the approximate width of a human hair, measurements should be taken of the distance from the hair to the screen (D), the distance between the centers of the rst dark bands in the diffraction pattern (y), and the average wavelength of the laser (λ). See Figure 32.2 for location of the rst dark bands. The number one (1) in the formula is indicative that these are the rst dark bands measured from the center of the diffraction pattern (the central maximum). The width of the hair (a) is calculated using the following formula. Note that all measurements should be in meters.
