Laser gas analyzer

A laser gas analyzer comprising:

• a laser diode that irradiates a measurement target gas with laser light;
• a light receiving unit including:
• a photodiode that receives the laser light that has passed through the measurement target gas;
• and
• a light emitting diode (LED) that irradiates LED light such that the LED light is received by the photodiode without passing through the measurement target gas;
• and
• a processor that:
• calculates a concentration of a component contained in the measurement target gas based on an amount of light of the laser light received by the photodiode, and
• determines presence of failure of the photodiode based on an output of the photodiode that receives both of the laser light and the LED light, wherein
• the laser diode intermittently irradiates the laser light,
• the LED irradiates the LED light at a predetermined timing during a period in which the laser diode does not irradiate the laser light,
• when the processor detects the LED light but not the laser light during the period, the processor determines that the light receiving unit is normal, and
• when the processor does not detect either the laser light or the LED light during the period, the processor determines that at least the light receiving unit is abnormal.