Final answer:
The binocular distance PD can be measured by drawing two lines on paper, determining the max distance at which they can be resolved, and then applying the diffraction formula to calculate the pupil diameter, comparing it to the average of 3 mm.
Step-by-step explanation:
To measure the binocular distance PD, also known as the pupillary distance, follow this procedure:
- Draw two lines several millimeters apart on a white sheet of paper.
- Move away from the sheet as it is held upright, and measure the distance at which you can just distinguish (resolve) the lines as separate. This is the maximum distance where the lines are resolved.
- Use the equation θ = 1.22λ/D to calculate D, the diameter of your pupil. In this equation, θ is the angle subtended by the lines at your eye, λ is the average wavelength for visible light, and D is the pupil diameter.
- Compare your answer to the average pupil diameter, which is typically about 3 mm.
It is essential to understand that this method uses the principle of diffraction to estimate the pupil size based on how light interacts with a small aperture (in this case, the pupil).