The grating element calculations from the diffraction pattern will agree very well with the spacing measured from analyzing the AFM images. The spacing of tracks in a DVD is about half as that in a CD giving it twice as many tracks per mm. This accounts for about a two fold gain in the capacity of a DVD relative to CD.
To obtain a very precise and accurate estimate of the line spacing on a compact disk (CD) by using the CD as an optical diffraction grating and making measurement of the diffracted laser light. Lasers are sources of coherent, monochromatic light.
Diffraction on a CD — Collection of Experiments
2019年7月18日 · A recording on a CD is in the form of microscopic pits of different lengths that carry the information. These pits are placed in rows of the same width and equal distance, which form a diffraction grating on the mirror surface of the CD.
Although a CD is not really a diffraction grating, after all the light bounces off of the CD, it does not pass through it, the CD acts like a diffraction grating because the reflected light undergoes constructive and destructive
diffraction grating. When we bounce light off of the CD bottom, the sets of ridges and valleys will diffract the light and produce a characteristic diffraction pattern on a screen. By measuring the geometrical features of the diffraction pattern, we can then estimate the …
However, one of the most common examples of a diffraction grating in your life time, is the compact disc(CD) or DVD. A CD has a spiral, grooved track (usually composed of pits). For a small region on the surface of a CD, the grooves create an approximately parallel pattern.
To use the CD as a grating, its surface should be masked with a black, matt paper disc from which a 0.03 x0.01 m rectangle has been cut out to provide an entry for a light beam. The disc is then supported so that its plane is vertical and the mask opening horizontal (figure I). With the CD I m away from a 3 m wide projec-
compact disc (CD) can be used as a diffraction grat-ing, even though its track consists of a series of pits, not a continuous groove. Previous authors described how to measure the track spacing on a CD using an incident laser beam normal to the surface 1 or one at an oblique angle. 2 In both cases, the diffraction pattern was projected on a
USING Cds and Dvds AS DIFFRACTION GRATINGS - DocsLib
Experiment Set-up: Diffraction Pattern CD grating Laser central spot screen Diffraction Images Equations { d (sinθ) = mλ m = 0, ±1, ±2, … d = distance between slits θ = angle of diffraction λ = wavelength of light m = the order # for the bright fringes { To find θ measure distance from grating to screen and the first order distance and ...
Two simple experiments with a CD, which works quite well as a reflecting optical diffraction grating, are briefly described in this article. The experiments allow estima-tion of the wavelengths of diffracted rays of light. The experimental setup is illustrated in fig. 1. As a source of light, a convenient elec-trical lamp labelled as L is used.