Hi, this is an update of where we are at with the fiber splitter temperature test. (Steph you can archive to the fiber splitter web site, thanks).
The chamber driving program works, and saves data in the attached file (an example). Tom and I have discussed Q&D methods to make a header/metadata that will be uniform for any automated processing but not be too much work, as this is a limited duration test. The chamber program allows one to select various “steps” or “levels”, their dwell time, and the range, e.g. 22deg C +/- 1deg C. It allows a certain amount of time to “get going” and then starts to monitor the STDs to see if the values are within range. Once they are, it starts a user determined run of some length. If it goes out of spec on the temperature or humidity, it doesn’t stop and start over, it just finishes that interval and goes to the next programmed step. It does not save the STD but does save the mean, min and max. The frequency of readings is user determined.
Any particulars you want in the chamber or photodiode file (see below) please send me and Tom and email.
Friday we put Channel 2 of our field portable Fluke 1620 Temperature and Humidity Data logger on the shelf in the middle of the chamber and ran it twice. Both requested the humidity be controlled as well as the temperature. For the first test, we didn’t wait long enough, and we may have asked it “to do the impossible” given our T,RH combinations. The second test (attached) was simpler – 22deg C and 50% RH, then 22deg C and 20% RH. During the first, short test, there was little correlation between the chamber T,RH and our Fluke. This improved for the second test, but still there were kind of weird swings, see below.
So, we convinced ourselves our Fluke is correct, and the differences are from some combination of long equilibrium times and not understanding the correct way to run the chamber and ask for control on the RH as well as temperature. Note the chamber was checked out by their tech recently and everything was a go.
Today we will run w/o humidity control, and we will put an additional thermistor in the chamber, taped to an Al block to simulate the fiber splitter. We don’t want to overrange anything.
Speaking of ranges, the FLUKE’s operating temperature is 0deg C to 50deg C and we plan to test this, once we are comfortable with the chamber not overshooting and melting our Fluke. We also think letting the humidity float for the fiber tests will be the easiest, OK?
Speaking of the fibers, the Fiberenseandsignals.com web site says nothing about temperature. We have six units:
P/N FOSC-UF-600SR-MM-0102 (multimode and not single fiber?). The S/Ns are
FOSR16050216, xxx220, xxx222, xxx223, xxx232, and xxx233
Mike can you find out what they say about operating temps?
The second data file for the test will have date/time, the two photodiode signals, their STDS, their ratio, and the ratio STD, along with the ambient Temp, RH and the internal Temp, RH as measured by our 2-channel Fluke 1620.
Red is RH, blue is Temp deg C. We were coming down from a test at 35deg C and 45% RH, but we had opened to door to vent to ambient before this second test.
B. Carol Johnson, Physicist
Sensor Science Division
NIST
Hi, just to let you all know where we’re at with this thermal chamber. Carol
From: Johnson, B. Carol (Fed)
Sent: Thursday, June 08, 2017 8:53 AM
To: Larason, Thomas C (Fed)
Cc: Miller, C Cameron (Fed) ; Allen, David W. (Fed) ; Curry, John J. (Fed)
Subject: thermal chamber tests
Hi, we ran with the humidity control on, asking for 20deg C and 30 deg C. Compared to the temp and RH measured at the center of the chamber with a Fluke 1620, the results did not agree. So we did three more runs, without the humidity control, and conclude there is something wrong with the air circulation in the chamber. Because the agreement improved when we added a fan. We have a service call scheduled for June 28.
- June 5 – no humidity control, Fluke 1620 inside air center; Fluke “probe” inside center touching aluminum test piece, we asked for 20degC then 30degC
- June 6 – same as June 5 but we added a 10k thermistor taped to the aluminum test piece (not logged, but observed), we asked for 30degC
- June 7 – same as June 6 but we added a fan to circulate the air. Then it finally worked. Carol (note “ADT” should be “80T” in the captions.)
Zoomed in on June 7 temperature data:
B. Carol Johnson, Physicist
Sensor Science Division
NIST
Hi, with the fan, the aluminum block follows the chamber temp (humidity is floating) but looks like we will need to wait longer (<3hr) for equilibrium. For the first run of the fiber splitters, we will start at 22deg C (they are stated 20 deg C to 70 degC) just to be safe. But we think we can do 20 because the chamber undershoot is short in time and does not affect the aluminum block temperature.
B. Carol Johnson, Physicist
Sensor Science Division
NIST
20 deg is pretty warm for a low temperature spec…at some point (for MOBY-Net) we should know where it is for temperatures lower than that. Would like to know down to 10 deg C….