Hey all:
As the thread topic suggest, we are planning on doing some experiments with laser gas sensors. These are available on the market; however, for our application, they are bulky and have extra features that are unneeded. We want to make a sensor that is just the bare sensor. Weight and space is an issue with these large sensors. I apologize in advance if this has been asked before.
What we were thinking of doing is using a laser emitter that emits light at 760nm for oxygen. The laser would be shot through the gas sample and then detected on the other side by a photo diode. The photo diode would be able to measure light intensity or power. This laser is based on the fact that the oxygen in the gas would absorb light at 760nm. Depending on the input and output power of the sensor, you can measure oxygen concentration in the sample.
I read somewhere on these forums that modulating or shooting the laser out at a frequency rather than just switching it on / off and reading would allow the laser light to be separated from other sources of light? How does this work?
How does gas temperature affect the system?
As this is a new design, we need help with the theory of this sensor. I believe this is how commercial sensors do the detection, but I am not sure. In the end, we want to create a low power (milliwatt) high response time sensor that would be able to be used in our application. We understand the complexity of the issue and are willing to work with it. Keep in mind that we are not chemists and are engineers. We don't know the specifics of every little thing.
Let me reiterate the fact that we cannot use commercial sensors because of the following reasons: They are bulky as in their dimensions are in the several inches, sometimes feet. We need something that can fit in an extremely small space - a few inches. They are expensive: hundreds of dollars or more. A laser emitter and a photo diode could be had for tens of dollars or less. They consume lots of power, most of the time several watts. Our application is very power strained. We are balancing power with several devices, so the lower the power the better. We would like to consume milliwatts compared to watts.
Thanks,
LostTime77
As the thread topic suggest, we are planning on doing some experiments with laser gas sensors. These are available on the market; however, for our application, they are bulky and have extra features that are unneeded. We want to make a sensor that is just the bare sensor. Weight and space is an issue with these large sensors. I apologize in advance if this has been asked before.
What we were thinking of doing is using a laser emitter that emits light at 760nm for oxygen. The laser would be shot through the gas sample and then detected on the other side by a photo diode. The photo diode would be able to measure light intensity or power. This laser is based on the fact that the oxygen in the gas would absorb light at 760nm. Depending on the input and output power of the sensor, you can measure oxygen concentration in the sample.
I read somewhere on these forums that modulating or shooting the laser out at a frequency rather than just switching it on / off and reading would allow the laser light to be separated from other sources of light? How does this work?
How does gas temperature affect the system?
As this is a new design, we need help with the theory of this sensor. I believe this is how commercial sensors do the detection, but I am not sure. In the end, we want to create a low power (milliwatt) high response time sensor that would be able to be used in our application. We understand the complexity of the issue and are willing to work with it. Keep in mind that we are not chemists and are engineers. We don't know the specifics of every little thing.
Let me reiterate the fact that we cannot use commercial sensors because of the following reasons: They are bulky as in their dimensions are in the several inches, sometimes feet. We need something that can fit in an extremely small space - a few inches. They are expensive: hundreds of dollars or more. A laser emitter and a photo diode could be had for tens of dollars or less. They consume lots of power, most of the time several watts. Our application is very power strained. We are balancing power with several devices, so the lower the power the better. We would like to consume milliwatts compared to watts.
Thanks,
LostTime77