The examination of microsamples by infrared spectroscopy is best accomplished by reduction of beam area with small apertures. However, this technique produces energy losses and aperturing effects which distort the baseline. Methods of dealing with energy losses and correcting baseline distortions by mechanical and digital means are examined.
Howard J. Sloane and Robert J. Obremski, "Microsampling in the Infrared — Use of Special Techniques," Appl. Spectrosc. 31, 506-515 (1977)