Measuring a human hair

Today we measured the thickness of a human hair by diffraction of light.
For a double slit diffraction of a light beam, light and dark interference spots are created on a surface some distance L from the slots.
If the slots are separated by a distance d,  the distance from the center bright spot and bright spot #m is y = λL*m/d
We treat the human hair as the separation between openings and if we shine a laser at the hair, we get a corresponding diffraction pattern on a distant surface.

We placed a whiteboard 1 meter away from the hair, to simplify calculations. our λ was 680nm for a red laser. We measured the distance between the center and the 4th bright spot and got y=4.8 cm
Rearranging and plugging in we got d = 680e-9*1m*4/.048 = 5.67e-5m = 56.7 μm

My hair is on the very lower border of human hair thickness according to google. Makes you think I have alopecia or something haha