Small bore ceramic laser tube inspection light table

Apparatus for inspecting small bore ceramic laser tubes, which includes a support base with one or more support rollers. A fluorescent light tube is inserted within the laser tube and the laser tube is supported by the support rollers so that a gap is maintained between the laser tube and the fluorescent tube to enable rotation of the laser tube. In operation, the ceramic tube is illuminated from the inside by the fluorescent tube to facilitate visual inspection. Centering the tube around the axial light of the fluorescent tube provides information about straightness and wall thickness of the laser tube itself.

BACKGROUND OF THE INVENTION 
The present invention relates to a light table apparatus to provide 
inspection capabilities for ceramic laser tubes, more particularly for 
small bore ceramic laser tubes. 
The operation of small bore ceramic laser tubes is well known in the art. 
One aspect of the proper operation of such laser tubes is the uniformity 
and thickness of the interior of the laser tube itself. Such aspects are 
very critical in connection with proper operation of the laser. 
Information regarding the straightness and/or wall thickness of the laser 
tube can have dramatic influence on the frequency of operation, the amount 
of power delivered from the laser, and the like. Such information can be 
extremely critical in many applications. 
In a laboratory environment such as at Lawrence Livermore National 
Laboratory in Livermore, Calif., the development of small bore lasers has 
been ongoing for experimental purposes. The operation of such lasers are 
used, for example, in an atomic vapor laser isotope separation (AVLIS) 
process. The operation of lasers in such an AVLIS process requires that 
the frequency and output power be maintained with extremely high accuracy. 
If the ceramic laser tubes for the lasers are not operating properly, this 
can have a dramatic and undesirable negative effect on the overall AVLIS 
process. 
One approach for inspection of such ceramic laser tubes utilizes 
conventional light bulb suspended on a pole. One person pushes the light 
bulb down the ceramic tube to illuminate the inside. This would provide a 
basis of visually inspecting the laser tube itself for any contamination. 
One significant problem with such an approach is the inability to uniformly 
provide visual inspection of the laser tube, because there is a large 
change in the lighting area surrounding the conventional light bulb, and 
shadows move along with the light. 
It would be desirable, therefore, to provide an improved inspection 
apparatus for providing information about the interior of a small bore 
ceramic laser tube. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an improved light table 
apparatus for indicating visual information in connection with a small 
bore ceramic laser tube. 
Briefly, the present invention provides an support base for a small bore 
laser tube which includes one or more support rollers. 
The support base further includes a fluorescent light tube source which 
provides a means for illuminating the interior of the laser tube to permit 
visual inspection thereof. 
In operation, the ceramic laser tube is placed over the fluorescent light 
tube, and the light tube is illuminated to facilitate visual inspection. 
Centering the laser tube around the axial light of the fluorescent tube 
provides information about the laser's straightness and wall thickness. 
Other objects, features and advantages of the present invention will become 
apparent from the following detailed description and in part become 
apparent to those skilled in the art upon examination of the following or 
may be learned by practice of the invention. The objects and advantages of 
the invention may be realized and attained by means of the 
instrumentalities and combinations particularly pointed out in the 
appended claims.

DETAILED DESCRIPTION OF THE DRAWINGS 
Reference will now be made in detail to a preferred embodiment of the 
invention, an example of which is illustrated in the accompanying 
drawings. While the invention will be described in conjunction with the 
preferred embodiment, it will be understood that it is not intended to 
limit the invention to that embodiment. On the contrary, it is intended to 
cover alternatives, modifications and equivalents as may be included 
within the spirit and scope of the invention as defined by the appended 
claims. 
Referring now to FIG. 1, an exploded perspective view of a ceramic laser 
tube inspection light table 10 is depicted. The present invention provides 
a means of uniformly illuminating a ceramic laser tube 28 so as to provide 
for visual inspection ability of the laser tube itself for contaminants 
and the like. 
The present invention, as depicted in FIG. 1, includes a support base 12 
and two fluorescent light sockets 14, 16. Socket 14 is spring loaded 
compressible and socket 16 is stationary. The present invention further 
includes a fluorescent tube 24 and means for illuminating (on/off switch 
20 and power line 18) fluorescent tube 24 when it is placed in electrical 
contact with the respective fluorescent light sockets 14, 16. 
The light table 10 further includes one or more support rollers 30, 32, 34, 
which can be adjusted, with suitable modification to Table 10, for 
predetermined heights depending on the size of the laser tube 28 which is 
undergoing inspection. In operation, a user will slide the fluorescent 
tube 24 within a ceramic tube 28 so as to leave a predetermined gap 40 (as 
seen in FIG. 2) between the interior wall of the ceramic laser tube 28 and 
the exterior wall of the fluorescent tube 24, for one reason that the 
fluorescent tube 24 would possibly be cut if it would come in contact with 
the ceramic tube 28. 
The user then places the fluorescent tube 24 in an electrical connection 
with the fluorescent light sockets 14, 16 so that the fluorescent tube 24, 
when illuminated by on/off switch 20, will be stationary. The support 
rollers 30, 32, 34 will provide for rotational support of the laser tube 
28 about the axis 22 of the fluorescent tube 24. 
A user can make a hallmark 36 on one edge of the ceramic tube 28 and then 
incrementally rotate the ceramic tube 28 in increments of 45.degree., 
90.degree. or the like, and thereby provide a uniform visual inspection 
capability when the fluorescent tube 24 is suitably illuminated. 
It has been found that, if there are defects in ceramic laser tube 28, a 
user of the present invention will see pinholes, cracks and the like. With 
respect to contamination of the walls, if a viewer sees a blue dot with a 
dark center with the visual inspection table, this could be an indication 
of cobalt contamination in the ceramic. If there is copper contamination, 
the viewer will see an orange-brown dot. With a reddish dot there is an 
indication of iron contamination. 
In the inspection process, the interior of the laser tube 28 is illuminated 
with no background lighting. The fluorescent tube 24 is illuminated and 
the ceramic 28 tube can then be inspected visually. If the tube is in 
suitable operating condition, the user will see a yellowish-white type of 
illumination from the fluorescent tube 24 which is inside the ceramic tube 
28. If there is a crack, the user will see light coming from the crack, or 
he will see a dark area that is like a pencil line over the area. 
If contamination exists, the user will see colored spots, as mentioned 
above. With respect to a pinhole, the viewer will see a bright point of 
light coming out of the laser tube that is not discolored. 
In further operation, the user can turn off the interior light of the 
fluorescent tube and illuminate the light table with an exterior light 
such as via a drafter's light fixture 42, as illustrated in FIG. 2. 
The support rollers 30, 32, 34 of FIG. 1 provide for supporting and 
centering of the ceramic tube 28 around the axis 22 of the fluorescent 
tube 24, as well as provide for rotation of the ceramic laser tube 28 
about the axis 22 of the fluorescent tube 24. This provides the capability 
of complete visual inspection of the ceramic tube 28 when rotated about 
the fluorescent tube 24. The centering is important in order to provide 
uniformity of the light from within the ceramic laser tube 28. The 
drafter's light 42, as illustrated in FIG. 2, is used for verification of 
any problems found during the inspection process. 
In a laboratory environment such described above, the needs and 
requirements are generally far greater for proper laser operation than in 
private industry. As a result, there is a tendency to have much higher 
quality standards of materials and there is a need for special processes 
and equipment to insure the quality standards, such as proper inspection 
of a ceramic laser tube. 
The foregoing description of a preferred embodiment of the invention has 
been presented for purpose of illustration and description. It is not 
intended to be exhaustive or to limit the invention to the precise form 
disclosed, and obviously many modifications and variations are possible in 
light of the above teaching. 
The present embodiment was chosen and described in order to best explain 
the principles of the invention and its practical application to thereby 
enable others skilled in the art to best utilize the invention in various 
embodiments and with various modifications as are suited to the particular 
use contemplated. It is intended that the scope of the invention be 
defined by the claims appended hereto.