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Laser drawing apparatus

  • US 5,892,611 A
  • Filed: 07/22/1994
  • Issued: 04/06/1999
  • Est. Priority Date: 08/11/1993
  • Status: Expired due to Fees
First Claim
Patent Images

1. A laser drawing apparatus comprising:

  • a splitting means comprising a beam splitter which separates laser light emitted from a laser source into two drawing beams, the beams being aligned in a common plane and a beam separator which separates each of the two drawing beams into at least two bundles of drawing beams;

    a deflecting mirror having a reflecting surface which reflects and deflects the aligned drawing beams to scan a drawing surface therewith in a main scanning direction; and

    ,a scanning optical system which converges the beams reflected by the reflecting surface of the deflecting mirror onto the drawing surface,wherein the height of the drawing beams on the drawing surface in said main scanning direction from the optical axis of said scanning optical system is limited to be in proportion to a deflection angle θ

    ;

    wherein there is the following relationship;

    
    
    space="preserve" listing-type="equation">δ

    =cos.sup.-1 {2 cos α

    ×

    cos.sup.2 ω

    -cos α



    =tan.sup.-1 {sin α

    /(2 cos α

    ×

    sin ω

    ×

    cos ω

    )}(δ

    sin γ



    )<

    p/fwherein"f" designates the focal length of the scanning optical system;



    " the incident angle of a drawing beam upon the reflecting surface of the deflecting mirror in a sub-scanning direction normal to said main scanning direction;



    " the angle of a line normal to the reflecting surface of the deflecting mirror with respect to a bisector of the optical axis of the scanning optical system and the axis of the incident beam;

    "p" the pitch of the aligned drawing beams;



    " the angle of the drawing beams reflected by the reflecting surface of the deflecting mirror with respect to the optical axis of the scanning optical system; and

    ,"γ

    " the angle of a line connecting an image forming point of the drawing beams reflected by the reflecting surface on the drawing surface and an intersecting point on the optical axis of the scanning optical system to the drawing surface, with respect to the sub-scanning direction.

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