For the double slit interference (Thomas Young 1901) the distance between the peaks b on the screen is derived by the well known formula b=H.l /D where H is the distance ftom the slits to the screen. D the distance between the slits and l is the wavelenght. So if D is not small (1-2 mm) the visibility of the peaks is unobservable.
Now the same must apply for the distance between the reference beam and points from the object. When this is D in holography and the same formula applies then there must not be intereference visibility - b should be very small. But holography interefernce is visible. How is that? Is there another formula and if yes why? I think holography is the closest to double slit Young experiment?
Dear Llian
In Young's experiment the interference of light takes place between the lights diffracted from same object but in holograph the interference of light takes place between the light reflected from mirror and object.
Thanks Sreenatha,
Do you think one would see interference from two slits on different plates far apart from each other? What changes in the formula if the slits are separated?
As a rule, the interference fringe structure period during hologram recording is very small and invisible by naked eye. This is a reason why high resolution recording medium is necessary for hologram recording.
Thanks Anatoly,
a quick calculation using the formula gives on a 2 m positioned screen and 10 cm between the rays 10 microns space between the fringes. Would they not be smeared by air turbulances if at all possible to see by a CCD? Also when there is some small uncertaintanty in the path it will increase beyond 10 micron.
Another issue is why they do not demonstrate the Young experiment with such high resolution medium?
Thank you in advance for colaboration.
Air turbulence does not prevent hologram recording in room conditions.
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