A group of students attempts to photograph a double-slit interference pattern…
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Waves Sound and Physical Optics · Waves Sound and Physical Optics
Problem
A group of students attempts to photograph a double-slit interference pattern directly on the image sensor of a lens-removed smartphone camera. The phone’s sensor has square pixels with a pitch of 1.4μm (center-to-center spacing). The double-slit apparatus uses a 500nm monochromatic laser, a slit separation of 0.25mm, and a screen distance of 0.80m.
Assume small-angle conditions apply.
(a) Without performing a detailed numerical calculation, assess qualitatively whether adjacent bright fringes are likely to fall on separate pixel rows (and therefore be resolvable) or overlap on the same row. Base your reasoning on proportional comparisons among the given quantities.
(b) If the students discover that the fringes are not sufficiently resolved, identify one parameter they could adjust (choose from wavelength, slit separation, or screen distance) to improve resolution on the sensor. Explain how changing that parameter would address the resolution issue.
(c) For the parameter you selected in part (b), predict qualitatively how making that adjustment would affect both the fringe spacing and the overall brightness of the recorded pattern, commenting on any practical trade-offs.