Patent ID: 6538739
Filing Date: 2003-03-25
Classification: A61B,G01N

Abstract:
A method for detecting the presence of a bubble, comprising:inserting a fiber optic into a liquid ambient medium, wherein said fiber optic comprises a proximal end and a distal end; coupling a first beam of laser light from a high repetition laser system into said proximal end, wherein said first beam of laser light emerges from said distal end within said liquid ambient medium; transmitting a second beam of laser light into said proximal end, wherein said second beam of light is partially reflected by said distal end to produce a reflected second beam, wherein as said bubble forms and grows at said distal end, the amount of light reflected by said distal end increases; detecting said reflected second beam to produce a detected signal; storing a first sample of said detected signal before said high repetition laser system fires said first beam of laser light; storing a second sample of said detected signal a predetermined delay after said high repetition laser system fires said first beam of laser light; and subtracting said second sample from said first sample to obtain a sample difference; such that if said sample difference is greater than a predetermined threshold level, continuing to fire said first beam of laser light from said high repetition laser system; or such that if said sample difference is less than said predetermined threshold level, controlling said high repetition laser system according to a method selected from a group consisting of (i) discontinuing firing said first beam of laser light from said high repetition laser system for at least a period of time, and (ii) increasing the power of said first laser beam, up to a predetermined power, until said bubble forms.