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Reports until 20:14, Sunday 17 October 2021
sudarshan.karki@LIGO.ORG - posted 20:14, Sunday 17 October 2021 - last comment - 08:58, Wednesday 20 October 2021(60294)
Temperature coefficient of Pcal transfer standard (TSA)

SudarshanK, RickS

We created two new transfer standard, TSA and TSB in order to facilitate the transfer of laser power calibration between the  national metrology institutes (NMIs) and the various observatories. We are in the process of characterizing these new transfer standard. We have made couple of measurements in the  last few weeks. The result from those measurements will be posted at same later date. Here we present the measurement of temperature coefficient of TSA that was made yesterday.

TSA was in the oven since 3:00 PM  Oct. 12, set at the temperature of 39 deg C. On October 13, the responsivity ratio between TSA and TSB were measured letting the TSA to cool from its heated temperature of 39 deg. C.

The measured temperature coefficient of the newly assembled transfer standard TSA is about 1.5 hops/deg C. When analyzing the data, the points where the temperature gradient is too high, in the beginning, and  where the standard has reached the equilibrium, towards the end, has been ignored. The first fit in the plot is made using all the data under consideration. The second fit is made by decimating the data in order produce equally spaced data and thus remove the bias that arises for having more data at lower temperature difference. The difference in temperature coefficient is minimal from these two different methods.

All the data and the jupyter notebook used to analyze the data can be found here:


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sudarshan.karki@LIGO.ORG - 20:18, Sunday 17 October 2021 (60295)CAL

An attempt to make a second temperature coefficient measurment on 10/14 failed because the laser tripped early on during the measurement. The partial data that was collected can be found here:



sudarshan.karki@LIGO.ORG - 08:58, Wednesday 20 October 2021 (60338)

As described in alog 60319, we retrospectively applied the correction for temperature dependence dark offset and temperature dependece responsivity on the refrence standard (TSB) for this measurement as well. The resultant temperature coefficient of TSA is now 1.85 hop/ deg C (K) as shown in the plot attached below. The data and the code for anlaysis lives in its original location.

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