【摘要】：研究了相敏式激光啁啾色散光譜法在高吸收度情況下的應(yīng)用.用窄頻半導(dǎo)體激光器作為光源,利用一工作于載波抑制模式的鈮酸鋰電光強(qiáng)度調(diào)制器調(diào)制單頻激光,在單頻激光兩側(cè)產(chǎn)生兩個(gè)邊頻分量,并通過兩邊頻分量產(chǎn)生外差干涉信號(hào).利用外差干涉的相位波動(dòng)來測(cè)量甲烷氣體位于1653.7 nm附近的折射率波動(dòng),通過氣體折射率與吸收系數(shù)之間的Kramers-Kronig關(guān)系計(jì)算甲烷氣體濃度.傳統(tǒng)的波長(zhǎng)調(diào)制光譜法受限于郎伯-比爾定律,在應(yīng)用于高吸收度的情況時(shí),存在靈敏度下降的問題,甚至出現(xiàn)隨氣體濃度上升輸出信號(hào)反而下降的現(xiàn)象.實(shí)驗(yàn)結(jié)果顯示,相同實(shí)驗(yàn)條件下,波長(zhǎng)調(diào)制光譜法的線性測(cè)量范圍為38.1—1500 ppm·m,線性測(cè)量的動(dòng)態(tài)范圍僅為16 d B;而相敏式激光啁啾色散光譜法在很大的吸收度范圍內(nèi)均具有線性輸出,檢出限低至47.3 ppm·m,線性測(cè)量范圍上限為174825 ppm·m,具有超過35 d B的動(dòng)態(tài)范圍.
[Abstract]:The application of phase sensitive laser chirped dispersion spectroscopy to high absorption is studied. The narrow frequency semiconductor laser is used as the light source. A single frequency laser is modulated by a lithium niobate electro-optic intensity modulator working in the carrier suppression mode. Two side frequency components are generated on both sides of the single frequency laser and heterodyne interference signals are generated by the two side frequency components. The phase fluctuation of heterodyne interference is used to measure the refractive index fluctuation of methane gas near 1653.7 nm. The concentration of methane gas is calculated by the Kramers-Kronig relation between the refractive index and absorption coefficient of methane. The traditional wavelength modulation spectral method is limited by Lombo-Beer 's law. In the case of high absorbance, the sensitivity decreases, and even the output signal decreases with the increase of gas concentration. The experimental results show that, under the same experimental conditions, The linear measurement range of wavelength modulation spectroscopy is 38.1-1500 ppm / m, and the dynamic range of linear measurement is only 16 dB, while the phase sensitive laser chirped dispersion spectroscopy has linear output in a wide range of absorption. The detection limit is as low as 47.3 ppm m, and the upper limit of linear measurement is 174825 ppm m, with a dynamic range of more than 35 dB.
【作者單位】： 清華大學(xué)精密儀器系精密測(cè)試技術(shù)及儀器國(guó)家重點(diǎn)實(shí)驗(yàn)室;
【基金】：國(guó)家重大科學(xué)儀器設(shè)備開發(fā)專項(xiàng)(批準(zhǔn)號(hào):2012YQ200182,2012YQ0901670602)資助的課題~~
【分類號(hào)】：O433
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本文編號(hào)：2186576