1. An apparatus for determining the level of one or more liquids in a test tube containing at least one liquid, comprising: a line generator positioned to project a line of light through said test tube; a light source positioned below said test tube and oriented to project light through the bottom of said test tube such that at least one layer of said at least one liquid is illuminated; an optical imager aligned to capture at least one image of the line when projected through said test tube and of the illuminated layer; and a microcontroller associated with said imager that is programmed to determine the level of at least one liquid in said test tube based on said captured image of said laser line projected into said vessel and said illuminated layer.