#optical properties
- Allochromatism — The property of certain minerals or crystalline substances to exhibit diverse colors due to the presence of fine chemical impurities, foreign inclusions, or defects in the crystal lattice, rather than their basic chemical composition. In their pure state, these minerals are usually colorless or white, the final color being accidentally determined by external factors during crystallization.
- Anastigmatism — An ideal optical property or characteristic of a lens or mirror system being completely free from astigmatism; the absence of asymmetric focusing distortions, allowing oblique light rays passing through the system to converge into a single precise focal point. This structural phenomenon guarantees uniform sharpness and an exceptional flatness of the image across the entire surface of the projection plane, eliminating marginal blurring.