Use of the Thorlabs Cold White LED was limited to the portable contact MFT developed by @Christel Pesme and @Andrew Lerwill. And, in fact, we did compare MFT results for 14 samples - 7 round-robin samples and 7 colors on an object - using xenon-arc and LED light sources; here's a link to the 2016 JAIC paper.
Subsequent work by the GRI and GCI with our non-contact Whitmore MFT only used the xenon-arc lamp, in part because of our comfort having used this light source since the beginning and a preference for its emission of a broad and continuous spectrum.
We hope to finally build upon the 2016 Pesme et al. study in the coming months by examining a larger sample set using our non-contact Whitmore MFT with a xenon-arc light source and Fotonowy MFT with a range of white LEDs. More to come soon!
Original Message:
Sent: 09-11-2025 16:16
From: Michael Crawford
Subject: Whitmore MFT: 2021 Parts List
Hi Mark, and Vincent,
Thanks very much for your detailed answers to my many questions. I think I now have a much better idea of the components we need to improve our MFT system.
Is there any reason you have not utilized your LED fiber optic source for MFT measurements? It would be interesting to see how results using the MCWHF2 LED source would compare with results using the Xe lamp for a variety of samples/chromophores.
Best regards,
Mike
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Michael Crawford
SRAL Volunteer
Winterthur Museum, Garden & Library
Glen Mills
United States
Original Message:
Sent: 09-08-2025 13:47
From: Mark Benson
Subject: Whitmore MFT: 2021 Parts List
Hello Michael,
I did my best to answer your questions below. I've also included an image of our tester head/boom stand assembly. This was something I overlooked when purchasing the instrument so we came up with this solution in house to get up and running quickly but I'm sure you can find some interesting solution with more flexibility online.
Thanks,
Mark
I have looked at BoliOptics boomstands, and noticed that you use a dual arm stand. Is that more stable than a single arm stand? I've never used a single arm stand so I can't say one is better than the other, I think it would depend on the quality and the specs of the stand overall. A nice feature of our dual arm model is that it has a bracket on each end with a hex nut so I can replace the existing metal rods with longer ones for testing larger objects.
Does it provide enough range of motion to measure objects that are vertical, or at other orientations, besides lying flat on a table top? To this point I've been able to test everything flat on the bench. If I need to test something on the wall, our tester head can be turned 90 degrees by loosening a nut attached to the Edmund optics single axis adjuster (98-24-014 in the parts list that Vincent posted).
How did you attach the MFT fiber probe head to the boomstand dual arm? Some type of gimbal mount? We cut and drilled out a piece of aluminum "U" channel. There are two hex nuts on one side that attach to the tester head and one that attaches to the Edmund optics single axis adjuster. The Edmund optics single axis adjuster is attached to a piece of aluminum "L" channel that we cut a drilled out to attach to the end of the microscope stand using its existing holes for mounting a microscope. See image.
And do you have any type of x-y stage adjustments, or do you just use the boom stand range of motion to position the probe head before focusing? We do not but I'm sure there are some products out there that could be used for more flexibility. As we encounter objects that need a special set up, we will have to modify our current set up.
Can you recommend a USB pen camera that provides high quality images of the focal region? And a fiber light source as well? I was planning to purchase a low cost optical fiber fault finder with a laser and SMA fiber optic connector but if you have a better suggestion please let me know. I purchased a digital USB microscope camera online. It's good enough but not the best. It's no longer available but like the one in the link below.
https://www.amazon.com/Opti-Tekscope-Digital-Microscope-Definition-1600x1200/dp/B00PEZ3GMK/ref=ab_dp_prsubs_d_sccl_1/141-3147817-9085249?pd_rd_w=vpFyM&content-id=amzn1.sym.b5b75f55-f4d9-4eb5-a0d6-ef050ac68649&pf_rd_p=b5b75f55-f4d9-4eb5-a0d6-ef050ac68649&pf_rd_r=8QXM9GHPPNX31RMQ1CGC&pd_rd_wg=7LAqw&pd_rd_r=f8e0c5ff-0b6a-4701-8ba4-88c6cada5961&pd_rd_i=B00PEZ3GMK&psc=1
I use a Thorlabs MCWHF2 LED for alignment. https://www.thorlabs.com/thorproduct.cfm?partnumber=MCWHF2
Finally, I was also considering a second light source based on a Thorlabs white LED (color temperature 4000 K), several neutral density filters (for the LED and the Xe sources), and some other light guiding and control accessories. Do you have any experience with that LED source, or suggestions for others that might be better? I only use the Xe for testing and the Thorlabs LED for alignment. The only experience I have with LED is with a "contact" LED MFT that we borrowed from the GCI years ago.
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Mark Benson
Assistant Conservator
Getty Research Institute
Los Angeles
United States
Original Message:
Sent: 08-29-2025 13:15
From: Michael Crawford
Subject: Whitmore MFT: 2021 Parts List
I am a volunteer at the Winterthur Museum in Wilmington, DE. I have been working with a basic Whitmore MFT and we are hoping to upgrade it to make it more stable, and more suitable for the range of conservation applications here.
Our MFT has a Xe lamp, CDI PDA spectrometer, and a probe head for two optical fibers with a short travel (about one inch) focusing translation stage. I would like to mount the probe head and its translation stage on a boom stand, which seems to be standard practice. I have looked at BoliOptics boom stands, recommended by Mark Benson in this thread, and noticed that at the GCI they use a dual arm stand. What type of boom stands have others used? Is the dual arm more stable than a single arm stand? Does it provide enough range of motion to measure objects that are vertical, or at other orientations, besides lying flat on a table top? How does the MFT fiber probe head attach to the boom stand horizontal arm? Some type of gimbal mount? And is it necessary to have any type of x-y stage adjustments, or is the boom stand range of motion sufficient to position the probe head before focusing?
I am also interested in recommendations for a USB pen camera that provides high quality images of the MFT focal region. As far as mounting the camera, it seems like most just adapt the fiber probe head by including a second 45 degree (to the excitation beam) opening into which the camera is inserted. Does this lead to any focusing issues?
Connecting a laser based fiber visual fault indicator to the collection fiber seems like a reasonable method to check the overlap of the Xe excitation spot and the scattered light collection fiber. Is that what others use? I have been using a FORS tungsten halogen light source for this purpose but it is not always available (and could be brighter).
Finally, we are also considering adding a second LED based light source for the MFT. One possibility we are considering is a Thorlabs MWWHF2 white LED (color temperature 4000 K). If any others are using that LED source we would appreciate hearing their opinion of it for MFT applications, or receive suggestions for other LED light sources that might be better.
Sorry for all the questions; any information you can provide would be very helpful.
Thanks and best regards,
Mike Crawford
Winterthur Museum
------------------------------
Michael Crawford
SRAL Volunteer
Winterthur Museum, Garden & Library
Glen Mills
United States
Original Message:
Sent: 02-26-2025 11:09
From: Henry Duan
Subject: Whitmore MFT: 2021 Parts List
I would be happy to share NARA's user experience with the previous Xe MFT system designed around ~2000. Understanding that after so many years, some of these experiences may no longer be relevant, due to the upgrade of the components used in the system in the past 2 decades.
I joined NARA and started to use the Xe-MFT system in the lab since the summer of 2012, and that Xe-MFT system was already installed for ~9 years but had not been actively used, perhaps due to some challenges from its instability and poor consistency in test outcomes. After a few months diving into the system, I identified some key issues in our system, and fixed them accordingly:
(1) The light output was highly unstable within a day of operation, even after 2 hrs. of warming up, during which the intensity went up, peaked around 2-3 hrs. and then coming down and drifting lower to a much lower level for a few hours, and then drifting back to up.
After some diagnostic work, I found it was due to the issue of the "intensity controlled" in the feedback loop. I communicated with a fellow researcher in CCI, Suzy Tsi. She told me she and others from different institutions had observed the same issue. Her solution was to remove the controller (disconnect the feedback loop). I did the same and it worked fine. I had also communicated and shared my date with Mr. Whitmore, and he agreed. I can share the chart of tracking the intensity drifting curve during a day, in case any one is interested. I assume Mr. Whitmore might have communicated with the system supplier and had fixed the operation of the controller by now. A normal intra-day drifting of light intensity should be <2% vs. the average, <1% would be considered very stable.
(2) The water chamber for cutting off deep IR. We found the water in it often showed a hazy appearance (we used D.I. water in the lab). Not sure it was the issue of our lab DI water, or the corrosion inside the chamber wall. We removed that water chamber and replaced it (together with the near-IR reflecting filter) using a "band-passing filter" which can cut both UV and IR (from near IR all the way to deep IR in micron wavelength level, wider and also cleaner/flatter than the water chamber can cut). I can share the T% curve of the "band-passing filter" in case anyone is interested. It has a good transparency between 400nm and 700nm (T~90%), although I still keep the original UV filter in the system, without the water chamber and near-R filter. Spectrophotometer measurement showed my IR component in the Xe light source is very low, near zero, and flat from >730nm to 3 micron (end of the detecting range). The band-passing filter is very stable after many years of use.
(3) The optical cable probes do not fit 100% tight into the exposure head. Any slight touch either on the optical cable or on the leads of the 2 probes may cause a wide swing of the detected light intensity by the photometer (we used the white calibration plate to reflect the light). The reason it is so sensitive to the alignment of the two probes is due to the requirement of a perfect overlap between the light spot on the test sample vs. the light spot detected by the probe to the photometer (both are <0.4 mm in diameters of the two spots). I can accept 70% overlap between the two spots, but must be stable, not moving around. We are using adhesive tapes to tightly glue the two probes onto the exposure head to prevent them movin around, as a temporary solution. The ideal solution would be to add x-y direction micro-adjust screws on one of the two probes, to allow users to adjust so that the detected reflection light can be tuned to the maximum.
I hope the above helps.
Original Message:
Sent: 2/25/2025 4:41:00 PM
From: Mark Benson
Subject: RE: Whitmore MFT: 2021 Parts List
Thanks for organizing and posting this Vincent.
At the Getty Research Institute, we used the GCI's Whitmore MFT for many years. Our comfort level with its operation and durability were the main factors in our decision to purchase this design. I also thought the broad spectrum and continuous SPD of the xenon-arc lamp would allow for some flexibility testing different lighting scenarios outside of the typical gallery setting. I used an MFT with an LED for many years with positive results, so this is in no way an argument against instruments with a different light source. At the GRI we are mostly screening collection material that will be displayed in a gallery lit with LEDs so I think either light source would work for us. Colonial Williamsburg was already working with MKS Newport to pull together the parts list when we contacted them, so a lot of the work had already been done but there was still a lot of discussion to address the issues mentioned in the notes and purchase the items not included in the Newport kit. I hope this list makes it easier for others to purchase in the future.
Mark
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Mark Benson
Assistant Conservator
Getty Research Institute
Los Angeles
United States
Original Message:
Sent: 02-24-2025 17:40
From: Vincent Beltran
Subject: Whitmore MFT: 2021 Parts List
While there are several iterations of the microfading tester (MFT) in use in the field, many institutions rely on the version based on the original design by Paul Whitmore (aka the Whitmore MFT). This version utilized components from Newport Oriel, which was purchased by MKS Instruments in 2016, and over the years some part numbers have changed.
With many thanks to @Mark Benson at the Getty Research Institute and @Gretchen Guidess at Colonial Williamsburg, we are sharing their 2021 MKS parts lists for the Whitmore MFT (see attached). Though mostly identical, note their embedded notes (highlighted in red) describing issues encountered during assembly and the different accessories purchased independent of MKS.
Hopefully, this aids in the maintenance of your Whitmore MFTs!
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Vincent Laudato Beltran
Scientist
Getty Conservation Institute
Los Angeles CA
vbeltran@getty.edu
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