Crystal conoscopy

Crystal conoscopy is used to check the quality of crystals.
If the pattern is not the same then the crystal will quickly become faulty.
Two polarizers are placed at the angle of 90 degrees, the crystal is placed between; the laser beam is directed on the crystal.
The lens or frosted glass should be placed in front of the polarizer so that the light was like a cone. Then the interference of horizontal and vertical polarization will be visible. A cross inside the niobate lithium in the middle of the figure shows vertical and horizontal polarization.
The conoscopy shows the structure of the crystal and when the voltage is supplied, a monoaxial crystal turns into biaxial and can act as a phase plate. These crystal properties are in action in optics and acoustics.
The embroidery is a conoscopic picture of different crystals in which the structure of the crystal is visible. With the help of embroidery encrypted circuits of various optical and acoustic devices of Atlantis and Lemurians. Different optical axes have different patterns. That is why in embroideries angles are encrypted at which crystals need to be cut