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公开(公告)号：US5572031A
公开(公告)日：1996-11-05
申请号：US344765
申请日：1994-11-23
CPC分类号： G01D3/0365 , G01J3/4338 , G01N21/39 , G01J2003/2866
摘要： RF modulation spectroscopy of a near-infrared tunable laser diode source is used to determine the oxygen concentration in a sample medium. A reference cell containing a known concentration of oxygen is used to calibrate the apparatus as well as to lock the laser on an oxygen absorption line. The temperature of the reference cell is monitored from which the pressure in the reference cell can be determined. Both the temperature and the pressure in the sample cell are monitored, either directly using independent transducers or indirectly using spectroscopic techniques. The oxygen content of the sample is determined, correcting for both temperature and pressure effects.
摘要翻译： 使用近红外可调激光二极管源的RF调制光谱来确定样品介质中的氧浓度。 使用含有已知浓度的氧的参比细胞来校准装置以及将激光器锁定在氧吸收线上。 监测参考电池的温度，从中可以确定参考电池中的压力。 监测样品池中的温度和压力，直接使用独立的换能器或间接使用光谱技术。 确定样品的氧含量，校正温度和压力的影响。
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公开(公告)号：US5317156A
公开(公告)日：1994-05-31
申请号：US827209
申请日：1992-01-29
CPC分类号： G01N21/39 , G01N2021/399 , G01N21/031 , G01N21/359
摘要： RF modulation spectroscopy of a near infrared laser diode source is used to determine the amount of a target substance in a breath sample. In this type of modulation the laser output is modulated to produce sidebands displaced from the laser carrier by the modulation frequency. The modulated beam is passed through a gas sample which differentially absorbs the sidebands, the result of which is the conversion of some of the laser frequency modulation into amplitude modulation which is subsequently detected using a broadband photodetector. In certain tests, the target substance is a particular isotope, whose concentration is measured as an isotope ratio. In order to measure the presence of first and second isotopic species, provision is made to provide laser illumination at characteristic wavelengths for absorption lines for the first and second isotopic species of the gas. This may sometimes be accomplished using a single laser diode and scanning at least one of its operating parameters in order to achieve one of the wavelength difference. Alternatively, first and second laser diodes operating at the first and second wavelengths are used.
摘要翻译： 使用近红外激光二极管源的RF调制光谱来确定呼吸样品中目标物质的量。 在这种类型的调制中，激光输出被调制以产生从激光载体偏移调制频率的边带。 调制光束通过差分吸收边带的气体样品，其结果是将一些激光频率调制转换成幅度调制，随后使用宽带光电探测器检测。 在某些测试中，目标物质是特定的同位素，其浓度以同位素比率测量。 为了测量第一和第二同位素物种的存在，提供了为特征波长提供用于气体的第一和第二同位素物种的吸收线的激光照明。 有时可以使用单个激光二极管实现这一点，并且扫描其操作参数中的至少一个，以便实现波长差之一。 或者，使用以第一和第二波长工作的第一和第二激光二极管。
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