In a laboratory, experimental infrared spectroscopy of atmospheric molecules is mainly studied in the gas phase. This chapter focuses on observation and measuring techniques. It is dedicated to Fourier transform infrared spectroscopy. The chapter includes a description of the operating elements related to technical aspects in the setup for observation or data analysis. Two types of interferometers are described, a laboratory interferometer and a commercial interferometer. The chapter provides examples of techniques that were applied for the study of molecules in the atmospheres of planets other than the Earth. It also includes a brief description of the spectroscopic ellipsometry technique, which is used for the study of materials deposited as thin layers on substrates. The chapter describes examples of devices used for space observation and analysis, one ex situ and the other aboard a space probe.