Laser beam combiner

A laser beam combiner housing is connected to a light pipe distribution system, and has a first beam path established for a principal lasing beam passing through an inlet aperture to an outlet aperture connected to the light distribution system. An internal mirror face transversely intercepts the first beam path and is aligned with a second laser beam path, so that the second laser beam will establish a line of incidence with the reflective mirror, and the corresponding line of reflection of said second laser beam will be collinear with the first laser beam path. The second laser beam is created by a low power visible spectrum laser generating unit, so that the light distribution pipes and corresponding reflective mirrors may be accurately aligned with the principal lasing beam path. The housing is also provided with cooling fluid to create controlled environment for the principal lasing beam.

BACKGROUND OF THE INVENTION 
The invention relates to laser beam distribution systems, and in 
particular, the invention relates to laser systems where it is desirable 
to align the laser distribution tubes and mirrors by means of a low power, 
visible laser beam. 
In a laser beam distribution system which generally originates at the 
outlet of a laser generator, it is necessary to align the laser 
distribution conduits, generally referred to as "light pipes" and 
reflective joint mirrors linking the light pipes. Many systems of short 
length can be aligned by simple measurement and placement of light pipes, 
but, for complicated and long distance, it is desirable to align the 
system by means of a lower power visible laser beam such as that provided 
by a helium-neon laser (HeNe). 
Frequently, the HeNe laser is the heart of a system, as in certain 
measuring systems, but, where the principal lasing unit forms an invisible 
beam, such as that found in a CO.sub.2 laser, and, where certain high 
power (1.5 kw) lasers may have an unfocused beam diamter of 5/8 inch, for 
example, it is necessary to very accurately align the central, principal 
lasing beam with the light pipe system, by means of other than the 
principal lasing beam. 
Applicant has devised a compact, reliable system for aligning a laser beam 
in a light pipe system, and, as a subset, the device provides convenient 
means for introducing cooling, or otherwise conditioned, fluid to 
establish a controlled environment for the lasing beam. 
It is therefore, an object of the present invention to provide a compact 
system for aligning a principal lasing beam with a light distribution 
system by means of an auxiliary lasing beam unit. 
Another object of the present invention is to provide a laser entry box 
having a conditioned fluid introduced therein to provide a controlled 
environment for a laser beam distribution system. 
SUMMARY OF THE INVENTION 
The invention is shown embodied in a laser beam combiner wherein a box-like 
housing has a principal laser beam inlet aperture aligned with a laser 
outlet aperture to define a first laser beam path, and a second laser beam 
inlet aperture is located in the housing transversely to the first laser 
beam path. A laser mirror is mounted in said housing, the mirror having a 
reflective face obliquely intercepting the first laser beam path and the 
face is angled with respect to the second laser beam inlet aperture to 
define a second nonlinear laser beam path comprising a line of instance 
and a line of reflection with respect to the laser mirror, the line of 
reflection being colinear with at least a portion of the first laser beam 
path through the laser outlet aperture. A principal lasing beam, for 
example a CO.sub.2 laser beam, is aligned with the first laser beam path 
through the housing, and a secondary, low power laser beam, in the visible 
spectrum is aligned with the second laser beam path to provide a reference 
for aligning the light pipe distribution system and accompaying reflective 
mirrors.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
GENERAL DESCRIPTION OF THE ROBOT 
FIG. 1 of the drawings illustrate a right side elevational view of a laser 
robot 10 having a laser generating unit 11 mounted on a floor nearly. The 
laser unit 11 may be any of a variety of industrial lasing units 
manufactured by companies such as Coherent General Company, 
Spectra-Physics, etc. The preferred laser unit 11 for many power 
applications is an invisible CO.sub.2 gas laser, emitting a laser beam 12 
along a horizontal path from the exit end 13 of the unit 11. The beam 12 
is directed into a beam combiner 14, exiting through a light pipe 15 which 
is a hollow tube connected to the beam combiner 14 and to a path-direction 
changing unit such as the corner mirror assembly 16 shown. The beam 
combiner 14 will be fully discussed in conjunction with FIGS. 2 and 3, to 
describe how the robot is cooled and how the beam 12 is aligned. The 
mirror assembly 16 directs the beam 12 downward along a vertical path 
through a light pipe 17 to a second mirror assembly 16 which redirects the 
beam 12 along a horizontal path through a light tube 18 into a base 19 of 
the robot 10. The light pipe 18 may be continuous in many applications, 
but for the preferred embodiment the pipe 18 may be replaced by two pipe 
sections 18a,b, with a beam switching box 20 located therebetween. The 
switching box 20 does not form a part of the present invention. 
Laser Entry Box 
Referring to the plan section of FIG. 2 and the front view of FIG. 3 
together, the laser beam combiner 14 of FIG. 1 is shown affixed to a 
mounting plate 400 mounted to the front, or exit end 13 of the laser 
generator unit 11. The beam combiner 14 is of welded construction, having 
a baseplate 401 extending past side flanges 402,403 secured by cap screws 
404. The baseplate 401 has a central horizontal hole 405 with clearance 
around the flange 406 of a laser entry tube 407, flange-mounted with 
screws 408 against the baseplate 400. The tube 407 has a central bore 409 
for the passage of the high power laser beam 12 emanating from the laser 
generator unit 11. The beam combiner 14 has a side plate 410 extending 
parallel to the laser beam 12, and an end plate 411 is aligned at 
90.degree. to the side plate 410. The end plate 411 has a threaded collar 
412 secured thereto, sealed with an O-ring 413, and the first light pipe 
15 is threadably received in the collar 412. The side plate 410 has a hole 
414 and spot face 415 covered by a transparent window 416 which is 
gasketed and held in position with buttonhead screws 417. A relatively 
low-power laser generator unit 418--for example, a helium neon (HeNe) 
laser, which emits a red visible light beam--is mounted at 90.degree. to 
the side plate 410 on a mounting bracket 419 fastened to the mounting 
plate 400. 
The laser unit 418 is aligned so that the incoming beam 420 will form a 
right triangle with the axis 421 of the light pipe 15. In order to do so, 
a base angle alpha is selected, and the apex angle delta would then be 
90.degree. minus alpha. A reflecting mirror 422 is positioned at the base 
corner 423 of the triangle, normal to a line 424 bisecting angle alpha. 
The mirror 422 is held against the end of a positioning plug 425 by a 
retaining cap 426 threadably received on the plug 425. The positioning 
plug 425 has a pilot 427 received in a close-fitting bore 428 in a thick, 
angled side wall 429 of the box 14, and a flange 430 is received against a 
fitting washer 431 to adjustably position the mirror 423. The pilot 427 is 
sealed with an O-ring 432, and the plug 425 is held in position by cap 
screws 433 received through the flange 430. The end 434 of the laser entry 
tube 407 is machined flat, normal to a line 435 bisecting angle delta, and 
a shallow counterbore 436 in the surface 434 receives a reflecting mirror 
437 which is retained by a retaining ring 438 and screws 439. The mirror 
437 is made of a material such as gallium arsenide (GaAs), or zince 
selenide (ZnSe), which is transparent to the working (CO.sub.2) beam, but 
partially relfective to the alignment (HeNe) beam--due to the difference 
in wavelength of the two beams. In order to assure that the low power, 
visible laser beam 420 is centered coaxially with the axis 421 of the 
light pipe 15, a tooling plug 440 is inserted to a close-fitting bore 441 
in the end plate 411 of the box 14. The plug 440 has a knurled outer 
diameter and has a small centered aperture 442 and a counter-drilled 
clearance hole 443. When the laser 418 is positioned correctly, the 
visible beam 420 will pass through the aperture 442. This beam 420 is 
utilized for aligning the various mirrors on the robot 10, since the 
higher-power main laser beam 12 is invisible to the eye. After aligning 
the laser components, the tooling plug 440 is removed, and the low-power 
laser unit 418 may, optionally, be turned off, or left on to track the 
larger-diameter, high-power beam 12. The entry box 14 has an additional 
side plate 444 enclosing the structure, having a welded circular flange 
445 and a clearance hole 446 therethrough. A thin mounting plate 447 is 
gasketed and secured to the flange 445 by cap screws 448, and the mounting 
plate 447, in turn, supports a vortex tube 449 by means of a threaded end 
450 passing through the plate 447 and secured with a locknut 451. The 
vortex tube 449 is of the type available from the Vortec Company, 
Cincinnati, Ohio, wherein compressed air enters through a side inlet 452 
at a first reference temperature. Through a vortex/spinning action, cold 
air will exit one tube end 450 and hot air will exit the other end 453. 
The cold air flows through the box 14 and down through the light pipe 15 
to cool the various laser components and to slightly pressurize the system 
so as to prevent the entry of airborne contaminants from the atmosphere. 
The laser mounting bracket 419 also carries an air filter 454 and pressure 
regulator 455 tubed in series with the vortex tube 449 to regulate and 
clean the air received from an air pressure source (not shown). 
It will be appreciated by those skilled in the art that the device may be 
provided with cooling fluids other than air, for example, inert, low cost, 
gaseous nitrogen. 
While the invention has been shown in connection with a preferred 
embodiment, it is not intended that the invention be so limited. Rather, 
the invention extends to all such designs and modifications as come within 
the scope of the appended claims.