Abstract There is disclosed a method of suppressing unwanted interference fringes which are produced at interfaces of photosensitive information carriers, for example, holograms or interferograms, by reflection of light. The typical carrier of the hologram information consists of a photosensitive layer bounded on one side by air, on the other by a transparent support such as glass. The recording of interference fringes is produced by two coherent beams which are simultaneously incident on the photosensitive layer. Unwanted interference fringes are removed by the application of an immersion layer to the photosensitive surface or to its transparent support, the thickness of which being varied in time during exposure.
A method as claimed in claim 1, characterized in that the variation in time of the thickness of the layer is effected by the displacement of a wedge-shaped transparent layer which has the same refractive index and is separated from the support of the information carrier by liquid immersion agent.
Claim 2
Dependent Claim
24 words
A method as claimed in claim 1, characterized in that an immersion agent or a wedge is used which in addition has light-absorbing properties.
Claim 3
Dependent Claim
27 words
A method as claimed in claim 1, characterized in that the immersion agent used is readily evaporating liquid, while if required a fan heater may be used.
Claim 4
Dependent Claim
39 words
A method as claimed in claim 1 characterized in that the immersion agent is O-xylene the refractive index of which is approximately equal to that of the glass of the photographic plate and to that of the photosensitive layer.
Claim 5
Dependent Claim
24 words
A method as claimed in claim 1 characterized in that during exposure the immersion agent is directionally modulated by acoustic waves of surface waves.
Claim 6
Dependent Claim
40 words
A method as claimed in claim 1 characterized in that the immersion agent is applied to the vertically arranged information carrier or its support by means of a nozzle so that it flows down after the fashion of a drop.
Claim 7
Dependent Claim
43 words
A method as claimed in claim 1 characterized in that when a photochromic or phototropic material is used as the information carrier the carrier-air interface move remote from the source of exposing radiation is directly provided with a layer of the immersion agent.