**Competition Venue - 12:30 PM**
Emily immediately began systematically testing each crystal. She set up a simple polarized light source and observed how each crystal affected the beam.
Crystal one: standard birefringence. The light split into two beams with perpendicular polarizations. Normal behavior for anisotropic crystals.
Crystal two: slight optical activity. The polarization plane rotated as light passed through. Also normal.
Crystal three caught her attention.
When she shone polarized light through it at certain angles, the transmitted intensity showed unexpected variations. Not simple refraction. Not standard polarization effects. Something more complex.
Emily adjusted the angle carefully, watching the intensity pattern. It was periodic, but with an unusual dependence on both rotation angle and incident wavelength. Multi-beam interference from internal crystal structure, she realized.
She had her phenomenon.
