Compositions and methods for drop boundary detection and radiation beam alignment

A method for determining the relative positions of a radiation beam, fluid stream and one or more particle detectors, comprising:

• (a) directing a radiation beam from a radiation source to a fluid stream, thereby producing scattered radiation;
• (b) contacting said scattered radiation with the reflective exterior of a wedge formed by a first reflective surface and a second reflective surface, said first and second reflective surfaces placed to reflect radiation scattered in different directions from said fluid stream to different alignment detectors;
• (c) selectively detecting radiation reflected to said different alignment detectors, wherein the relative amount of radiation intensity reflected to each of said different alignment detectors correlates with the positions of said radiation beam and said fluid stream, and
• (d) observing an image of said fluid stream on a pinhole mirror, wherein said pinhole mirror has at least one pinhole positioned to pass radiation from said fluid stream to at least one particle detector when said image of said fluid stream is at a desired position and when a desired relative amount of radiation intensity is reflected to each of said different alignment detectors.

A method for monitoring drop formation in an oscillating fluid stream, wherein drops separate from said oscillating fluid stream at a drop break-off point that is in phase with upstream drop boundaries, comprising:

• (a) directing a radiation beam to contact an oscillating fluid stream at an observation point, thereby producing scattered radiation;
• (b) detecting a change in said scattered radiation, wherein said change correlates with a drop boundary at said observation point in said oscillating fluid stream;
• (c) locating said drop break-off point in said oscillating fluid stream;
• (d) determining the phase between said drop boundary at said observation point and said drop break-off point, and
• (e) identifying from said phase the number of drops that will occur before said drop boundary reaches said drop break-off point.

A method for assigning a particle in an oscillating fluid stream to a drop that breaks off of said oscillating fluid stream, comprising:

• (a) directing a radiation beam to contact an oscillating fluid stream at an observation point, thereby producing scattered radiation;
• (b) detecting a change in said scattered radiation, wherein said change correlates with a drop boundary at said observation point;
• (c) detecting a particle that is adjacent to said drop boundary in said oscillating fluid stream;
• (d) locating the drop break-off point in said oscillating fluid stream;
• (e) determining the phase between said drop boundary at said observation point and said drop break-off point, and
• (f) identifying from said phase the number of drops that will break off of said oscillating fluid stream before said drop boundary reaches said drop break-off point, thereby assigning said particle that is adjacent to said drop boundary in said oscillating fluid stream to a drop.