Patent ID: 6542317
Filing Date: 2003-04-01
Classification: G02B,H01L

Abstract:
An optical system for a crystallization tool for producing a crystallized silicon thin film by using an excimer laser as an exposure light source to crystallize an amorphous silicon thin film through a fine stripped pattern, comprising 1st to 10th lenses sequentially arranged along an optical axis from said excimer laser, including an optical part having birefringence material to control a depth of focus of the light passing through said 10th lens,said 1st lens having both sides made convex; said 2nd lens having one side made convex toward said light source and the other side concave; said 3rd lens having one side made convex toward said light source and the other side concave; said 4th lens having both sides concave; said 5th lens having both sides made convex; said 6th lens having one side concave toward said light source and the other side made convex; said 7th lens having one side made convex toward said light source and the other side concave; said 8th lens having both sides made convex; said 9th lens having one side made convex toward said light source and the other side concave; and said 10th lens having both sides made convex, wherein said optical part includes two birefringence material, each having a polarized light component perpendicular to each other.