All Flashcards
Compare phase change upon reflection from a higher vs. lower index of refraction.
Higher to lower: No phase change. Lower to higher: 180-degree phase change.
Compare constructive vs. destructive interference.
Constructive: Waves in phase, amplitudes add. Destructive: Waves out of phase, amplitudes subtract.
Compare reflection vs. refraction regarding phase change.
Reflection: May cause a phase change, depending on refractive indices. Refraction: Does not cause a phase change.
Describe the process of thin film interference.
- Light strikes a thin film. 2. Part of the light is reflected at the first interface. 3. Part of the light is transmitted and reflects at the second interface. 4. The two reflected waves interfere constructively or destructively.
How does an antireflection coating work?
- A thin film is applied to a surface. 2. The film's thickness is one-quarter of the light's wavelength in the coating. 3. Light reflected from the two surfaces of the coating undergoes destructive interference. 4. Reflection is minimized.
What is the effect of a 180-degree phase change upon reflection?
It can lead to destructive interference if the path length difference is also considered.
What is the effect of increasing film thickness on reflected wavelengths?
Thicker regions tend to reflect longer wavelengths (reds, oranges).
What is the effect of using an antireflection coating?
It minimizes unwanted reflections by causing destructive interference of reflected light.
What is the effect of normal incidence on thin film interference?
Maximizes interference effects due to the maximized path length difference.
What is the effect of oblique angles on thin film interference?
Reduces the path length difference, affecting the interference pattern.