Optical In-Line VCSEL Testing
Article by Dr. Martin Finger
Measurements of laser diodes with a pulsed operating mode are also possible. Novel high power VCSEL arrays require additional quality control of their spatial light distribution. This includes testing single emitter characteristics on the array as well as the measurement of the far-field emission pattern. Testing VCSELs with nanosecond pulses becomes important for time-of-flight applications.
Array spectroradiometers satisfy the exacting requirements for spectral resolution, throughput volume and reliability in a production environment. They are thus ideally suited to optical in-process inspection of laser diodes. In addition, array spectroradiometers can be used for the measurement of pulsed operation laser diodes and are an effective measurement method for use in the laboratory, too. The rise of VCSEL arrays imposes new challenges on production testing. Especially, spatial measurements in the near and far field of a VCSEL array are required. Camera-based imaging systems and conoscopes are suitable for production testing of spatial VCSEL characteristics. In-line testing of VCSELs with nanosecond pulses will become more and more relevant with their increasing spread in time-of-flight applications.