Interference by reflection on a CD

Click For Summary
SUMMARY

The discussion centers on the phenomenon of light interference patterns observed when a focused beam of light interacts with a CD. It establishes that the spatial coherence of the light source, such as a lens-focused LED or sunlight, is crucial for producing clear interference patterns. The conversation also highlights that diffuse light sources can create less distinct color separations, raising questions about the coherence necessary for such patterns. A referenced paper discusses the coherence properties of various light sources and their impact on image sharpness in holographic displays, emphasizing the importance of phase uniformity for interference effects.

PREREQUISITES
  • Understanding of light coherence and its significance in optics
  • Familiarity with interference patterns and their formation
  • Knowledge of light sources, including coherent and diffuse types
  • Basic principles of optics related to lenses and mirrors
NEXT STEPS
  • Research the coherence properties of different light sources in detail
  • Explore the principles of interference patterns in optics
  • Study the effects of spatial coherence on image quality in holography
  • Examine the role of pupil size and light source characteristics in visual perception
USEFUL FOR

Optics students, physicists, and anyone interested in the principles of light behavior and interference phenomena.

MaxLinus
Messages
5
Reaction score
0
TL;DR
Interference by reflection on a CD implies coherence?
A fairly focused beam of light incident on a CD projects a clearly visible interference pattern onto a screen.
May I infer that it has good (or at least enough) spatial coherence?
This property is evident, for example, in a lens-focused beam of light produced by a LED or by a ray of sunlight that filters directly through a half-closed window.
Nonetheless, less intense colour separation can be seen even when diffused light reflects on the CD (or soap bubbles, or oil stains on a rainy day). Would a completely non-coherent light produce such patterns?
 
Science news on Phys.org
Addendum. Found a partial answer in this paper: Coherence properties of different light sources and their effect on the image sharpness and speckle of holographic displays
 
One must be very careful to define what one means by coherence. In this case one is interested in the phase uniformity for a particular color of light traveling the multiple paths from source to detector required for interference. The CD is a figured mirror. The path of light onto the CD then into your pupil is limited both by the size of your pupil and the characteristics of the source. Your eye will see colors from a diffuse source. A point source will produce colors that project onto a wall. But a diffuse source will not project colors onto the wall.
 

Similar threads

  • · Replies 66 ·
3
Replies
66
Views
7K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 14 ·
Replies
14
Views
3K
Replies
2
Views
2K
  • · Replies 24 ·
Replies
24
Views
3K
  • · Replies 7 ·
Replies
7
Views
1K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 1 ·
Replies
1
Views
3K