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Illumination device using a pulsed laser source a Schlieren optical system and a matrix addressable surface light modulator for producing images with undifracted light

  • US 5,486,851 A
  • Filed: 07/19/1994
  • Issued: 01/23/1996
  • Est. Priority Date: 10/30/1991
  • Status: Expired due to Term
First Claim
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1. An illumination device for producing models used for manufacturing electronic elements, or for direct illumination of wafers or substrates during photolithographic steps for producing the electronic elements, or for direct illumination of structures including light-sensitive layers, comprising:

  • a pulsed laser light source;

    a pattern generator;

    an object onto which light emitted by said laser light source is focussed, said object being selected from the group consisting of a model, a disk, a substrate and a structure;

    said pattern generator includes an optical Schlieren system and an active, matrix-addressable surface light modulator,said surface light modulator has a reflective surface having addressed surface areas which diffract incident light and non-addressed surface areas which reflect incident light,said Schlieren system comprises a Schlieren lens arranged on a side of said surface light modulator, a projection lens facing away from said surface light modulator, and a mirror device which is arranged between said Schlieren lens and said projection lens for directing light coming from said pulsed laser light source onto said reflective surface on said surface light modulator,wherein said Schlieren lens is arranged from said surface light modulator a distance less than a focal length of said Schierlen lens,focussing means for focussing the light coming from said light source in at least one point which is spaced apart from said mirror device and which is adapted to have associated therewith at least one virtual point light source by reflecting a point at said mirror device,a filter device arranged in a diffraction image plane of the virtual point light source between said Schlieren lens and said projection lens, said filter device being designed to filter out diffracted light reflected by the addressed surface areas of said surface light modulator and permit undiffracted light reflected by said non-addressed surface areas to pass through said projection lens to the model, the disk, the substrate, or the structure, and to filter out undiffracted light reflected by said non-addressed surface areas of said surface light modulator, and permit said diffracted light reflected by said addressed surface areas to pass through said projection lens to the model, the disk, the substrate, or the structure, anda displaceable positioning table capable of having the model, the disk, the substrate or the structure secured thereon in position so that a sharp image of said surface areas of said surface light modulator can be formed on the model, the disk, the substrate, or the structure,wherein said pulsed laser light source is constructed such that a pulse duration of said pulsed laser light source is shorter than a minimum structural dimension of the model, the disk, the substrate or the structure divided by a displacement rate of said positioning table, andwherein, during the displacement of said positioning table, the model, the disk, the substrate or structure are composed of a plurality of partial images by adequate addressing of said surface light modulator.

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