End cap incorporating laser alignment target

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to the drawings, there is shown in FIG.
1 a pipe string 16 including two elongate pipe sections shown at 18 and 20 in a trench 21.
While only two pipe sections are shown, it is to be recognized that pipe string 16 when complete includes multiple coaxial pipe sections.
Pipe sections 18 and 20 are formed of polyvinyl chloride (PVC) and are substantially identical in shape.
Pipe section 18 includes a spigot end 22 and a larger diameter bell end 24.
Pipe section 20 likewise has a bell end 26 and a spigot end 28 inserted into bell end 24 and thus shown in broken lines.
A proper alignment of the pipe sections in string 16 is critical.
Typically the intention is to form a straight line piping string, in which all of the piping sections are coaxial, i.
e.
centered on a longitudinal axis 29.
One particularly effective approach is to generate a beam of monochromatic energy, e.
g.
laser energy, as a visible longitudinal axis.
A laser generator 30, supported in trench 21 near spigot end 22 of pipe section 18, generates a laser energy beam 32 that propagates longitudinally along and within pipe sections 18 and 20, and pipe sections subsequently added to the string.
Pipe section 18 is aligned first.
Then, each subsequent pipe section is aligned as it is added to the string.
When pipe section 18 has been aligned, laser generator 30 can be mounted within that pipe section if desired.
Laser beam 32 can be radially centered within the pipe sections, but need not be.
If the beam is not centered, its radial offset from center must be consistent along all of the pipe sections.
A transparent or otherwise light transmissive target is removably mounted to each pipe section and used to align that pipe section with respect to the laser beam.
In connection with FIG.
1 it is assumed that pipe section 18 is already aligned, and that pipe section 20 requires alignment.
Accordingly, a target assembly 34 is mounted to bell end 26.
The point at which laser beam 32 impinges upon the target, visually indicates the degree of alignment