- Why does blue light bend more than red light in the lens?
- For most transparent materials like glass, the refractive index is higher for shorter wavelengths (blue light) than for longer ones (red light). This property is called normal dispersion. Since the bending angle of light at an interface depends on the refractive index (via Snell's Law), blue light experiences a stronger refraction, leading to a shorter focal length.
- Is chromatic aberration only a problem for lenses? What about mirrors?
- Chromatic aberration is a refractive effect, caused by wavelength-dependent refraction. Mirrors operate on the principle of reflection, where the angle of reflection equals the angle of incidence for all wavelengths. Therefore, a simple mirror does not suffer from chromatic aberration, which is why reflective telescopes are often used to avoid color fringing.
- What is the main simplification in this simulator, and how does it differ from a real lens?
- This simulator uses the paraxial approximation, tracing rays very close to the optical axis at small angles. Real lenses have finite apertures, so rays hitting the edges cause spherical aberration and other defects. Furthermore, real white light contains a continuous spectrum, not just three discrete colors, and the Cauchy equation is an approximation that works best in the visible range away from absorption bands.
- How do lens designers correct for chromatic aberration in real devices like camera lenses?
- Designers create achromatic doublets by combining two lenses made of different types of glass (e.g., crown and flint) with different dispersion properties. The lenses are shaped so that the dispersion of one largely cancels out the dispersion of the other, bringing two specific wavelengths (often red and blue) to a common focus, dramatically reducing color fringing.