Browse Prior Art Database

Efficient and Reliable Optical Scanning System for Laser Processing of Three Dimensional Objects

IP.com Disclosure Number: IPCOM000109484D
Original Publication Date: 1992-Sep-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 5 page(s) / 225K

Publishing Venue

IBM

Related People

Koschmeder, MJ: AUTHOR [+2]

Abstract

Described is a systematic concept for an optical system that is simple, reliable, and efficient for three-dimensional (3-D) laser processing of an object. It consists of the injection of the laser beam into a central beam distributor that rotationally distributes the beam about an axis through the center of the object; the distributed beam is transmitted to multiple beam processing optics (sequentially or simultaneously) located on a circle centered at the axis. Each circumferential beam processing optics directs the beam onto the object being processed.

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Efficient and Reliable Optical Scanning System for Laser Processing of Three Dimensional Objects

       Described is a systematic concept for an optical system
that is simple, reliable, and efficient for three-dimensional (3-D)
laser processing of an object.  It consists of the injection of the
laser beam into a central beam distributor that rotationally
distributes the beam about an axis through the center of the object;
the distributed beam is transmitted to multiple beam processing
optics (sequentially or simultaneously) located on a circle centered
at the axis.  Each circumferential beam processing optics directs the
beam onto the object being processed.

      As background information, the technique of laser-treating a
two-dimensional (2-D) object has been extensively practiced in
various types of manufacturing.  Such laser-treating can include
ablation (for removal of thin coating), deposition of thin film
(e.g., for reworking of lithographic mask or integrated circuits),
planarizing surfaces (via melting of metal films), hardening
surfaces, local alloying, doping of Si, and so on.  These prior-art
laser treating of 2-D objects typically rely on optical systems
schematically indicated in Fig. 1 (a) and (b), where the 2-D image is
produced by x-y motion of the object (keeping the beam spot fixed) or
by x-y motion of the beam spot (keeping the object fixed).  Such
schemes are really conveniently usable for 2-D laser treatment only.
For 3-D treatment, such schemes can be extended by rotating the
object, but this would require a rotational device that holds the
object and rotates it along 2 perpendicular axes to be able to expose
all sides of the object to the laser spot; this is frequently not
practical in a production environment because of cost, time, and
complexity.

      A straight-forward extension of Fig. 1 (b) for 3-D laser
treatment of a fixed object is indicated in Fig. 1 (c).  Here, the
laser beam is directed onto a first mirror that rotates on one axis,
and then deflected sequentially onto various other mirrors that
rotate along different axis.  In principle, such a 3-D laser-spot
scanning approach could be made operational for 3-D laser treatment
of the fixed object but, in practice, such an asymmetrical scanning
system (as indicated in Fig. 1 (c)) causes the laser-spot to be
elongated in some slanted direction and the scanning of the
laser-spot to be also skewed on each face of the object making
precise laser-treatment of the object difficult if not impractical.
In contrast, the invention described in the following is a highly
symmetrized version of a 3-D scanning laser-spot system that produces
well-defined and constant spot shape and scan direction at all sides
of the fixed part being laser processed.

      Fig. 2 shows the schematic concept of the present invented
design for an improved 3-D laser-spot scanner on a fixed part.  It is
composed of 3 parts schematically:
(1) A beam-shaping and injec...