Can Laser Intensity Stabilization Be Improved for Precise Measurements?

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SUMMARY

The discussion centers on the stabilization of laser intensity using a Thorlabs CPS180 collimated laser setup, which includes polarizers, a beam splitter, and photo-diodes. The user reports an intensity variation of 0.2mV during the first hour of measurement, with fluctuations attributed to warming effects. Key suggestions include checking the supply voltage to the laser and monitoring polarization ratios as the laser warms up. The user is advised to ensure the laser operates within specifications and to consider the average intensity value for better analysis.

PREREQUISITES
  • Understanding of laser operation and characteristics
  • Familiarity with LabVIEW for measurement and data acquisition
  • Knowledge of optical components such as polarizers and beam splitters
  • Basic principles of photo-diode functionality and response
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  • Investigate laser intensity stabilization techniques for the Thorlabs CPS180
  • Learn about monitoring supply voltage effects on laser performance
  • Research the impact of temperature on polarization ratios in lasers
  • Explore advanced LabVIEW programming for improved measurement accuracy
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Researchers and engineers working with laser systems, optical measurement specialists, and anyone involved in precision laser applications requiring stable intensity measurements.

ssmoke
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I'm working with a setup involving a collimated laser (Thorlabs model CPS180), two polarizers, a beam splitter, and 2 photo-diodes. While measuring the intensity of the laser via LabView, without changing any of the components, I find the intensity varies by 0.2mV for the first hour of measurement. it increases for about the first half hour, then decreases for the next 15 minutes before even starting to stabilize. This seems like very odd behavior, even if the laser needs some time to warm up.

For my experiment, it is important that the laser be stable to within a few hundreths of a milliVolt. Do you think the problem is with my laser, photo-diode, or even the LabVIEW program?

If the problem is with my laser, is there a simple way to stabilize the intensity?
 
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You might want to check the supply voltage to the laser to make sure it isn't changing, hence changing your wavelength and power a bit. I'm also not sure how the polarization ratio in these lasers changes as they warm up. Are you monitoring it after you pass it through your optics?
 
I think most of my measurements have been taken with at least one polarizer.
 
You mentioned how much the laser intensity changed, but not the average value (i.e the relative change). How large was it?
 

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