The Intoxilyzer 5000 works on the theory of infrared absorption. The machine has a light bulb positioned at one end of a breath capture cylinder. There are filter wheels at the other end of the cylinder and on the other side of these filter wheels is a light receiver.
A person suspected of or under arrest for DUI will blow into a breath tube which leads to a breath chamber cylinder. The machine shines a light through this cylinder and the filter wheels will be spinning on the other end of the breath tube chamber. The infrared light causes the alcohol molecules to “vibrate” or “absorb” light at a particular frequency. The filter wheels are designed to filter out potential contaminants.
The amount of the breath sample and any reading of alcohol are very minute. The machine must make a multiplication conversion to an amount great enough for us to understand. The difference in light emitted and received is computed through a computer program in the machine to come up a value that can be compared to a .08. The conversion the machine makes on the differences in light would be the equivalent of taking the paper towel tube and increasing its size to that of a 55 gallon drum! Any error would then be exaggerated by that amount.