Which part of the Intoxilyzer 9000 is responsible for detecting infrared light?

The correct answer identifies the Infrared energy (light) detector as the component specifically responsible for detecting infrared light in the Intoxilyzer 9000. This device operates based on the principle of infrared spectroscopy, where it emits infrared light through the sample provided by a subject, typically their breath.

The Infrared energy detector then measures the absorption of the infrared light as it passes through the sample chamber filled with breath. Different compounds, including ethanol, absorb infrared light at specific wavelengths. By evaluating how much light is absorbed, the system can determine the concentration of alcohol in the breath sample.

This process is essential for accurate breath alcohol analysis, making the Infrared energy detector a critical component in the overall functionality of the Intoxilyzer 9000.

Meanwhile, although the sample chamber contains the breath sample and facilitates the interaction with infrared light, it does not detect the light itself. The processing unit handles the data analysis and calculations following the detection but doesn't participate in the actual detection of infrared light. Lastly, while the lens aids in focusing the infrared light onto the detector, it does not engage in the detection process itself.