Definition
Lenses are transparent objects (usually glass) that use refraction to converge or diverge light rays to form images.
Why It Matters
We see the world through manipulation of light. Understanding geometric optics is essential for designing everything from corrective eyewear to high-powered telescopes, allowing us to focus the “noise” of the environment into a clear, usable image.
Core Concepts
- Converging (Convex) Lens: Thicker in the middle. Converges parallel rays to a focal point. Can form both real and virtual images.
- Diverging (Concave) Lens: Thinner in the middle. Diverges rays as if they came from a focal point in front of the lens. Always forms virtual, reduced images.
- Polarization: The alignment of light’s transverse electric vibrations. Polaroid filters block light in all but one orientation.
- Aberrations:
- Spherical: Light at the edges of a lens focuses at a different point than light at the center.
- Chromatic: Different colors focus at different points due to dispersion.