We report the development of a field-deployable infrared laser spectrometer using new commercial diode laser technology at 2.68 μm. The instrument is designed to measure in situ CO2 concentrations open to the atmosphere at ground level. Absorption lines were carefully selected around 2.68 μm to minimize interferences from neighboring water vapor transitions. We provide details of the instrument design and data processing. The long term stability of the instrument was evaluated using the Allan variance technique. A preliminary evaluation of the instrument performance was realized by in situ measurements of CO2 concentration on the rooftop of our laboratory.