The 1st, 2nd and 3rd order least square method (LSM-1, LSM-2 and LSM-3) is applied to smooth the experimental absorption signal of 13 CO 2 and 12 CO 2 obtained by the tuneable diode laser absorption spectroscopy method in the 4860–4880 cm −1 frequency range of a tuneable diode laser. It has been shown clearly that using LSM-2 with a filter window N ~ 100 allows the 13 CO 2 content in exhaled air to be measured at an error level of 0.28%, which meets breathing tests requirements.

中文翻译：

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应用最小二乘法处理可调谐二极管激光吸收光谱法在4860–4880 cm -1范围内获得的信号，以解决呼出气中13 CO 2含量的问题

应用一阶，二阶和三阶最小二乘方法（LSM-1，LSM-2和LSM-3）对通过可调谐二极管激光吸收光谱法获得的13 CO 2和12 CO 2的实验吸收信号进行平滑处理。可调谐二极管激光器的4860–4880 cm -1频率范围。已经清楚地表明，使用LSM-2的过滤窗为N〜100，可以测量呼出空气中13 CO 2的含量，误差水平为0.28％，这符合呼吸测试要求。