Laser System Environmental Sensor Module: Hardware Development
Laiho, Aleksi (2024)
2024
Master's Programme in Electrical Engineering
Informaatioteknologian ja viestinnän tiedekunta - Faculty of Information Technology and Communication Sciences
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Hyväksymispäivämäärä
2024-04-22
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202403283200
https://urn.fi/URN:NBN:fi:tuni-202403283200
Tiivistelmä
Lasers are not used only in laboratories for peculiar experiments, but they are increasingly found in the lives of ordinary people. Nowadays even smartphones and cars have lasers embedded in them. From all of the different laser types, semiconductor lasers dominate the markets with their quantity.
Semiconductor lasers produce coherent and monochromatic light from electric current with over 70 percent efficiency. However, over time the efficiency decreases slowly and in some cases, abruptly. The degradation of laser is a well-studied subject and some of the degradation sources are temperature, humidity, electrostatic discharge, and mechanical shock. Their mechanisms are explained.
To better protect the optimal operation of the semiconductor laser, it is crucial to operate the laser in an environment where the degradation sources are controlled and their effect mitigated. The laser system is responsible for controlling the temperature of the laser and the laser diode is protected against humidity by hermetic sealing. However, there are still conditions that are controlled by the user of the laser system. Their task is easier when the environmental parameters are known. To achieve this, an environmental sensor module (ESM) is included in the laser system.
The requirements of the ESM are identified. It is to be operational even when the laser system is powered off. This results in the need for battery-powered operation, as well as low current consumption. The ESM stores data from its sensors with changing intervals depending on the duration of the system shutdown.
Based on the requirements, the components are selected and the circuit board is designed. The operation of the ESM is tested and especially the low current consumption is verified.
Due to insufficient firmware, not all features could be tested on the fully assembled unit. Rather, features and sensors were tested with the help of Raspberry Pi and other equipment. Results show that the target of five-year operation with battery power was achieved.
Although one of the most interesting sensors was the mechanical shock sensor, its operation could not be designed nor tested as wished. It remains to be seen in action how the feature will work and maybe some modifications will be made.
Semiconductor lasers produce coherent and monochromatic light from electric current with over 70 percent efficiency. However, over time the efficiency decreases slowly and in some cases, abruptly. The degradation of laser is a well-studied subject and some of the degradation sources are temperature, humidity, electrostatic discharge, and mechanical shock. Their mechanisms are explained.
To better protect the optimal operation of the semiconductor laser, it is crucial to operate the laser in an environment where the degradation sources are controlled and their effect mitigated. The laser system is responsible for controlling the temperature of the laser and the laser diode is protected against humidity by hermetic sealing. However, there are still conditions that are controlled by the user of the laser system. Their task is easier when the environmental parameters are known. To achieve this, an environmental sensor module (ESM) is included in the laser system.
The requirements of the ESM are identified. It is to be operational even when the laser system is powered off. This results in the need for battery-powered operation, as well as low current consumption. The ESM stores data from its sensors with changing intervals depending on the duration of the system shutdown.
Based on the requirements, the components are selected and the circuit board is designed. The operation of the ESM is tested and especially the low current consumption is verified.
Due to insufficient firmware, not all features could be tested on the fully assembled unit. Rather, features and sensors were tested with the help of Raspberry Pi and other equipment. Results show that the target of five-year operation with battery power was achieved.
Although one of the most interesting sensors was the mechanical shock sensor, its operation could not be designed nor tested as wished. It remains to be seen in action how the feature will work and maybe some modifications will be made.