Method and arrangement for spectroscopically measuring the concentration of a component of a gas sample

摘要

An arrangement for making gas spectroscopic measurements includes a laser diode driven by a modulated control current, a monitor diode, a detector unit for receiving a measurement signal of the transmitted radiation and a lock-in amplifier. The method utilizing the above arrangement is improved in that the offset component in the output signal of the lock-in amplifier is eliminated. This is achieved in that the radiation power of the laser diode is controlled to a pregiven modulation profile with the monitor diode functioning as an actual-value transducer.