Seminarium Optyczne

In this study, we focused on measuring the temperature in a turbulent flow without disturbing the flow at thetemporal resolution of ~1 second and the spatial resolution of 1 mm3 with accuracy better than 0.1 K. We attempted tomeasure temperatures using pure rotational bands of N2 and O2. We present a highly accurate Raman spectrometerbased on a laser diode tuned to the resonant absorption line of the 85Rb isotope near 780.0 nm. A heated glass cellcontaining Rb atoms was used as an ultra-narrow band atomic absorption notch filter with a bandwidth of 0.1 cm-1 andoptical density as high as four. This filter was placed in front of the spectrograph and blocked up to 99.99% of theelastically scattered laser light, which made it possible to observe the unobscured pure-rotational Raman spectra ofmolecular atmospheric gases. The relative intensities of pure-rotational Raman transitions were then used to inferatmospheric temperature changes.Additionally Spontaneous Raman roto-vibrational spectroscopy was used to measure the ratio of 13CO2 to12CO2 in the breath of a healthy person. We estimated that the changes in the isotopic composition of carbon dioxide atthe level of one part in 100 could be monitored with our apparatus. Experimental data were collected during4 minutes-runs in order to obtain sufficient signal-to-noise ratios. The achieved sensitivities made our Ramanspectrometer suitable for a rapid medical diagnosis with very broad applications. It can be used for numerousbiomedical tests with 13C labelled markers.