By using a pair of polarizing filters and a property of certain materials called birefringence we can photograph the hidden stresses in hard plastics.
In a darkened room. Turn on the laptop and create a white screen, I used clipboard on a Thinkpad 380 running win98, or you can create a white image in an editor and view it full screen. Mount the camera on the tripod and point it at the laptop screen, zoom in until the screen fills the camera’s field of vision. If you haven’t already, fit the polirizing filter onto the camera, slowly rotate the camera filter until the laptop screen goes black (you need to use the lcd on the camera, an optical viewfinder won’t turn black ;-)). When the screen appears black from the camera’s perspective we’ve achieved “cross polarization”. Now we can start with the pictures.
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