Techniques are used to determine when interfering beams of light are precisely
aligned at the core of the fiber when a laser interferometer is used to burn diffraction
gratings into optical fibers. Two alternative methods are disclosed for performing
this function, namely, refraction of the UV fluorescence through the fiber onto
a paper or screen, and alternately interrupting the left and right UV beams, then
directly observing the fluorescence pattern of the UV beam on the fiber core to
determine alignment.
