How To Judge The Quality Of Infrared Laser Diodes

Visual inspection:
Check the appearance of the diode, which should have no obvious damage, cracks, or oxidation.
Observe whether the pins are intact, without any breakage or corrosion.
Multimeter testing:
Use the diode test mode of a multimeter and connect the red and black probes to the two pins of the diode. Under normal circumstances, the forward conduction voltage should be between 1V and 2V, and the reverse resistance should be close to infinity.
If the forward conduction voltage is much lower than 1V or much higher than 2V, or the reverse resistance is very small, it indicates that the diode may be damaged.

Functional testing:
Connect the infrared laser diode to the circuit, drive it to emit light through current, and observe whether infrared light can be received using an infrared receiver or infrared camera.
If the receiver can receive the signal, it indicates that the diode is working properly.
Comparative method:
Compare two old and new infrared laser diodes of the same model. If there is a significant difference in performance between the two under the same testing conditions, it may indicate that one of the diodes has a problem.
Professional instrument testing:
Use professional instruments such as spectral analyzers or optical power meters to test the emission power, wavelength, and other parameters of infrared laser diodes, and compare them with the data on the specification sheet to determine whether their performance meets the requirements.
Temperature test:
During operation, the temperature of the infrared laser diode will rise. The temperature distribution can be observed using a thermal imager, and under normal circumstances, the temperature should be evenly distributed without any abnormal hot spots.