Laser gas analysis apparatus
A timing generating circuit outputs, to a laser controller, a change pulse signal for changing an oscillation wavelength of the laser beam, and outputs, to a data acquisition circuit, a timing pulse signal for outputting data to a processor. An edge detection circuit detects an edge of a measurement signal outputted from a detector circuit. A delay measuring circuit receives a change pulse signal outputted from the timing generating circuit, receives an edge detection signal outputted from the edge detection circuit, and measures a delay of a time for which the laser beam with an oscillation wavelength changed based on the change pulse signal reaches the detector circuit after the change pulse signal is outputted from the timing generating circuit. The timing generating circuit delays a time for outputting data from the data acquisition circuit to the processor based on the delay of time outputted from the delay measuring circuit.
1. A laser gas analysis apparatus comprising:
a light source unit including a semiconductor laser configured to emit a laser beam into process gas and a laser controller configured to control an oscillation wavelength of the laser beam;
a detector circuit configured to detect the laser beam transmitted through the process gas;
a data acquisition circuit configured to receive a measurement signal outputted from the detector circuit and to remove noise contained in the measurement signal;
a processor configured to receive data outputted from the data acquisition circuit and to compute concentration of the process gas;
a timing generating circuit configured to output, to the laser controller, a change pulse signal for changing the oscillation wavelength of the laser beam and to output, to the data acquisition circuit, a timing pulse signal for outputting data to the processor;
an edge detection circuit configured to detect an edge of the measurement signal outputted from the detector circuit; and
a delay measuring circuit configured to receive the change pulse signal outputted from the timing generating circuit, to receive an edge detection signal outputted from the edge detection circuit, and to measure a delay of a time for which the laser beam with an oscillation wavelength changed based on the change pulse signal reaches the detector circuit after the change pulse signal is outputted from the timing generating circuit,
wherein the timing generating circuit is configured to delay a time for outputting data from the data acquisition circuit to the processor based on the delay of time outputted from the delay measuring circuit.
2. The laser gas analysis apparatus according to claim 1 , wherein:
the detector circuit includes a light receiving element, a variable gain amplifier and an A/D converter, and the data acquisition circuit includes an integrator and a memory.