RESUMO
An overall quantum conversion efficiency of 7.8% is achieved by intracavity mixing the signal and idler of a 1.064 µm pumped Rb:PPKTP optical parametric oscillator in BaGa4Se7. In this way, a pulse energy of â¼0.71 mJ is generated at â¼7 µm for a repetition rate of 100 Hz. Tuning of the mid-IR radiation is demonstrated by heating of the Rb:PPKTP crystal.
RESUMO
The infrared laser photoacoustic spectroscopy (LPAS) and the pattern-recognition-based approach for noninvasive express diagnostics of pulmonary diseases on the basis of absorption spectra analysis of the patient's exhaled air are presented. The study involved lung cancer patients ( N = 9 ), patients with chronic obstructive pulmonary disease ( N = 12 ), and a control group of healthy, nonsmoking volunteers ( N = 11 ). The analysis of the measured absorption spectra was based at first on reduction of the dimension of the feature space using principal component analysis; thereafter, the dichotomous classification was carried out using the support vector machine. The gas chromatographymass spectrometry method (GCMS) was used as the reference. The estimated mean value of the sensitivity of exhaled air sample analysis by the LPAS in dichotomous classification was not less than 90% and specificity was not less than 69%; the analogous results of analysis by GCMS were 68% and 60%, respectively. Also, the approach to differential diagnostics based on the set of SVM classifiers usage is presented.
Assuntos
Testes Respiratórios/métodos , Neoplasias Pulmonares/diagnóstico , Técnicas Fotoacústicas/métodos , Doença Pulmonar Obstrutiva Crônica/diagnóstico , Idoso , Idoso de 80 Anos ou mais , Testes Respiratórios/instrumentação , Estudos de Casos e Controles , Expiração , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Pessoa de Meia-Idade , Reconhecimento Automatizado de Padrão , Técnicas Fotoacústicas/instrumentação , Análise de Componente Principal , Sensibilidade e Especificidade , Máquina de Vetores de SuporteRESUMO
A BaGa4Se7 nanosecond optical parametric oscillator (OPO) shows extremely wide idler tunability in the mid-IR (2.7-17 µm) under 1.064 µm pumping. The â¼10 ns pulses at â¼7.2 µm have an energy of 3.7 mJ at 10 Hz. The pump-to-idler conversion efficiency for this wavelength reaches 5.9% with a slope of 6.5% corresponding to a quantum conversion efficiency or pump depletion of 40%.
RESUMO
A 1.064 µm pumped Rb:PPKTP optical parametric oscillator (OPO) generates mid-IR radiation by intracavity mixing the resonant signal and idler waves in AgGaSe2. The â¼6 ns pulses at â¼7 µm have an energy of 670 µJ at 100 Hz, equivalent to an average power of 67 mW. The overall quantum conversion efficiency from 1.064 µm amounts to 8%, and the power conversion efficiency is 1.2%.
RESUMO
A AgGaSe2 nonlinear crystal placed in a coupled cavity is intracavity pumped by the ~1.85-µm signal pulses of a 1.064-µm pumped Rb:PPKTP doubly-resonant optical parametric oscillator (OPO) operating at a repetition rate of 100 Hz. Using two samples cut for type-I and II phase-matching, the overall idler tunability of the singly-resonant AgGeSe2 OPO covers an unprecedented spectral range from 5.8 to ~18 µm in the mid-IR.
