This video details an unexpected observation of optical interference fringes while polishing a piece of stone or crystal. The creator, working with broadband light sources (monitor and LED lamp), initially noticed fringes when placing the polished stone on their desk. Surprised by this given the lack of monochromatic light, they then tested the piece on an optical flat, again observing fringes that indicated the polished surface was not parallel to the flat. Further investigation by placing the optical flat on top of the stone revealed unusual multicolored fringes, which the creator had not previously encountered, further confirming the non-flatness of the surface and highlighting the unexpected behavior of the stone's optical properties under common lighting conditions.
Unexpected Optical Phenomena During Stone Polishing
0:00 Initial Polishing and Discovery: The video creator is polishing a piece of stone/crystal using diamond paste and observes unexpected optical fringes when placing the piece on their desk.
0:32 Unexpected Fringes: The presence of fringes is noted despite using broadband light sources (monitor, LED light), which is unusual as interference fringes are typically best observed with monochromatic light and optical flats.
0:50 Understanding Fringes: The creator explains that these are optical interference fringes, with light bands representing constructive interference and dark bands destructive interference, caused by light reflecting off surfaces and interfering.
1:47 Testing on an Optical Flat: The stone is placed on an actual optical flat, and fringes are still observed, indicating the polished surface of the stone is not flat or parallel to the optical flat.
2:29 Optical Flat on Top: When the optical flat is placed on top of the polished stone, the creator observes small, unusual multicolored fringes, confirming the surface is not flat and noting the multicolored aspect is unexpected.
2:51 Surface Not Flat: The presence of these fringes, especially the multicolored ones, reinforces the conclusion that the polished surface of the stone is not optically flat.