Mystery Thermography related item ... just a bit of fun for you :) - Page 1
Forum section: electronics / general

author: Fraser
author_rank: Super Contributor
timestamp: March 09, 2017, 10:00:54 pm
content: I thought I would post some pictures of a 'mystery' item for newbies to Thermography to identify.I know what it is and what it is for and so will the Thermographers on this forum. Lets see how long it takes for those less familiar with thermography as a science to identify the object and explain its useI suspect that many will Google it but please try to work it out from the pictures alone. Imagaine you just saw it in a junk shop and were trying to identify its purpose. I have already helped by saying that it is Thermography relatedJust a bit of fun, sorry no prizes for first correct answer. Remember, not just what it is, but its purpose as wellFraser

author: Bruno28
author_rank: Regular Contributor
timestamp: March 09, 2017, 10:08:00 pm
content: No idea what it is and I only got my first thermal camera about 6 weeks ago.But my guess is something to do with light absorption on different colour (white/black) to see how different colours can radiate heat?And this would help selecting the right emmissivity settings?I can't identify that thing sticking out of it as it's a dark photo.I most likely am talking nonsense haha.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 09, 2017, 10:16:10 pm
content: Hmm, whole faces, solid colored, white, black, copper? What could it be?Tim

author: lukier
author_rank: Unknown
timestamp: March 10, 2017, 12:33:54 am
content: Emissivity calibration target?

author: Platonas
author_rank: Contributor
timestamp: March 10, 2017, 06:21:36 am
content: They look like Aluminum cubes that are painted (or covered) with different color on each surface. Emissivity is the target of the coloring, I guess.The strange item on top could be a thermometer in order to have the real temperature of the structure and then compare it with the Thermal reading.

author: amv
author_rank: Contributor
timestamp: March 10, 2017, 09:09:06 am
content: Hi FraserI am sure those different coloures have some meaning.But i seem to remember you had a project with some remote control of cameras.So i am going old school on this one.A homemade joystick for remote controling cameras.Jan

author: CJay
author_rank: Super Contributor
timestamp: March 10, 2017, 11:38:53 am
content: I've little to no idea about thermography but I had a thought that it looks like it might be some sort of reference assembly used in a 'camera', then I saw that it wasn't the same on all sides so now I'm with Platonas and Lukier in thinking it's some sort of external reference/target for calibration.

author: bookaboo
author_rank: Frequent Contributor
timestamp: March 10, 2017, 11:43:51 am
content: Emissivity calibrator of some sort but I cant work out what the spindle type thing is for.

author: Codebird
author_rank: Regular Contributor
timestamp: March 10, 2017, 11:54:58 am
content: I think people may be over-thinking the spindle.My guess is that the spindle is just an attachment point for a handle, so you can pick it up and slot it into place on some piece of equipment under calibration without getting your grubby fingerprints all over the nice shiny metal.

author: Fraser
author_rank: Super Contributor
timestamp: March 10, 2017, 01:00:51 pm
content: Some excellent suggestions so far. Well done all. I will not spoil the fun just yet but will reveal its name and purpose later.Sorry the pictures are dark.... it is actually quite hard to photograph with a flash active. A direct side effect of its design !Just to explain the little silver 'spindle' ..... it is the hand grip point for removing the top cover to reveal the hollow interiorThe unit measures 100mm x 100mm x 100mm and is made of copper or tin, depending upon manufacturer.Side 1 is bare clean copperSide 2 is Gloss black paintedSide 3 is Matt black paintedSide 4 is Gloss white paintedTop and bottom are Gloss black paintedThe unit is often to be found on a manual or slowly rotating turntable.Finally, this is still current technology ! I bought it only this week, new and boxed.It is so well known that it actually was given the inventors name.Fraser

author: chris_leyson
author_rank: Super Contributor
timestamp: March 10, 2017, 01:20:24 pm
content: Thanks for the hint Fraser, a bit of googling found it. Wouldn't have occured to me to fill it with hot water though

author: PedroDaGr8
author_rank: Super Contributor
timestamp: March 10, 2017, 08:49:09 pm
content: Some strange version of an integrating sphere?

author: Fraser
author_rank: Super Contributor
timestamp: March 10, 2017, 08:49:46 pm
content: Solution:It is Leslie's CubeThis experiment apparatus is used to study the laws of thermal radiation in terms of surface temperature and emissivity of surface finish.I attach some reading on the use of such an apparatus.A good understanding of thermodynamics and the laws of thermal radiation is essential to the professional thermographer.https://en.wikipedia.org/wiki/Leslie_cubeWhen looking at a target surface, the Thermographer must consider the emissivity of that surface and its ability to both radiate and absorb thermal energy. If a surface is low emissivity and highly reflective, it can very easily produce thermal reflections from the surrounding environs, leading to erroneous readings even if the emissivity on the non contact measuring equipmentis correctly set. Look at teh attached picture from Wiki and you will see the low emissivity surface providing a clrar reflection of the hand next to it. Also note that eteh colour of a surface coating is seen by a human in the visible light spectrum and does not indicate that surface emissivity in the thermal spectrum. Black abd white painted surfaces can have very similar emissivity which differs greatly to their visible light reflectivity.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: March 10, 2017, 08:52:48 pm
content: Another page on Leslie's Cube plus a thermal image of it workinghttp://www.techknow.org.uk/wiki/index.php?title=Leslie%27s_CubeFraser

author: Fraser
author_rank: Super Contributor
timestamp: March 10, 2017, 09:10:12 pm
content: For those unaware, the Leslie's Cube may also be used to demonstrated how to improve the emissivity of a surface by adding nothing more exotic than simple PVC electrical tape. Colour is not important as the emissivity of the tape is a product of the PVC material from which it is made. Emissivity tables normally detail the emissivity of PVC Electrical tape. 0.95 is the generally accepted emissivity for generic electrical tape.This can be very useful when needind to measure the surface temperature of any shiny metal surface provided the surface temperature is within the capabilities of the tape to survive and not melt. Other tapes of differing materials may also be used but emissivity may differ. Wax crayons have also been used to improve emissivity of surfaces for non contact measurements.FLIR have a page on this topic......http://www.flir.com/science/blog/details/?ID=71556Fraser

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 10, 2017, 10:33:55 pm
content: From SED:https://dl.dropboxusercontent.com/u/53724080/Thermal/Cool1.JPGhttps://dl.dropboxusercontent.com/u/53724080/Thermal/Cool2.jpg(That's Kapton tape, hard to see against the similar colored copper in that lighting.)Electrical tape maybe not so good, because it's thicker and less conductive -- any heat dissipating through it will cause temperature drop through the tape, so you'll read somewhat low. In still air, and at modest temperatures, it should be within a few degrees still.Tim

author: eliocor
author_rank: Unknown
timestamp: March 10, 2017, 11:20:29 pm
content: A nice trick taught to me by a thermographic technician is to use white out tape, especially when measuring small parts...I always keep one of those dispensers in my E4+ pelican case

author: Chanc3
author_rank: Frequent Contributor
timestamp: March 12, 2017, 09:04:26 pm
content: We used to do the same, but with specific emissivity tape. Was great until they changed the composition, thus e value!Good mini quiz Fraser. Got two of these in the cupboard, so had to refrain from commenting!Sent from my iPad using Tapatalk

author: bookaboo
author_rank: Frequent Contributor
timestamp: March 13, 2017, 02:52:48 pm
content: A tip given to me by someone who looks for faults in marble floor heating was to "scuff" the entire floor using car wax (dont rub it off obv). Then on smaller areas vinyl tape.