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Figure 12. Photograph of an MTEC Photoacoustics Model PAC300 Nicolet ESP photoacoustic detector, which incorporates automatic accessory recognition and set-up.
MTEC sample holder cups accept samples as large as 10 mm in diameter by 6 mm thick. The IR beam is focused into a 5-mm-diameter area in the center of the cup in MTEC detectors. This consideration, combined with the fact that the signal evolves from a sample depth of well under a millimeter, indicates that much smaller samples than the holder cup size are adequate to produce the maximum signal level possible for a particular material. If suitably sized specimens are not available, they are typically produced using a punch, razor blade, scissors, file, abrasive or other means of size reduction. MTEC detectors have stainless steel sample cups that insert into the holder