Flow meter having a background pattern with first and second portions

A flow meter, comprising:

• a first image sensor having a first field of view, wherein the first image sensor is positioned to view a drip chamber within the first field of view;
• a background pattern positioned within the field of view of the first image sensor, wherein the background pattern includes first and second portions, wherein the first portion of the background pattern is different from the second portion of the background pattern;
• and
• at least one processor operatively coupled to the first image sensor, wherein the at least one processor is configured to:
• receive a first image from the first image sensor, and
• estimate at least one parameter of liquid within the drip chamber in accordance with a distortion of the background pattern caused by the liquid as indicated by the first image.

A method for monitoring a drip chamber, comprising:

• positioning a background pattern behind the drip chamber, the background pattern includes first and second portions;
• capturing a first image of the drip chamber including the background pattern;
• examining a distortion of the background pattern;
• and
• estimating at least one parameter of liquid using the examination of the distortion.