Thermal cameras that having "more real" colors? - Page 1
Forum section: electronics / general

author: naze
author_rank: Newbie
timestamp: June 11, 2019, 02:31:50 pm
content: Currently all thermal cameras are using monochrome or false color to display, because their sensors are monochrome. However thermal energy actually having a wide range of spectrum, so why not make a camera that can distinguish different wavelength, and reproduce the picture the way similar to visible light cameras? I think that will allow the picture to have more detail than now.

author: wraper
author_rank: Unknown
timestamp: June 11, 2019, 02:43:44 pm
content: Quote from: naze on June 11, 2019, 02:31:50 pmBecause they don't detect different wavelength. Usual cameras don't do that either, they just have 3 different color filters in front of pixels. And why would you care about wavelength if you measure temperature to begin with.

author: Vipitis
author_rank: Frequent Contributor
timestamp: June 11, 2019, 02:45:45 pm
content: There are dual band cameras. Working in LWIR and MWIR. These are just prototypes and classified in some way. They basically just arrays of two or three cameras.LWIR is very broad but it's also low energy and putting a Bayer matrix with expensive filters in front of the sensor will cut down the signal by at least 50%

author: cnxunuo
author_rank: Regular Contributor
timestamp: June 12, 2019, 01:14:30 am
content: most items are gray body, in LWIR. not much color information you can get out of them, due to their relatively flat emissivity vs wavelength.

author: Ultrapurple
author_rank: Super Contributor
timestamp: June 12, 2019, 09:06:53 am
content: Yes, everyone has hit it on the head: there isn't a lot of difference in appearance between (say) 14µm and 7µm (the LWIR spectrum), though thereisa difference between the LWIR and MWIR ranges.These images give an idea of those small differences:(Original reference paper here, or look up DOI:10.1109/LEOS.2009.5343133)(click for original source)There are a few dual-band sensors out there and a lot of work has been done on working out how the optics and arrays need to work. A Google search on 'dual band thermal' is revealing.

author: Ben321
author_rank: Frequent Contributor
timestamp: June 14, 2019, 08:04:17 pm
content: Quote from: naze on June 11, 2019, 02:31:50 pmThat would be a very interesting experiment. A VOX camera, with each pixel having a different microscopic LWIR bandpass filter in front of it. Maybe wavelengths being 9000nm 11000nm and 13000nm, with the shortest wavelength mapped to blue and the longest mapped to red. So you would have a full RGB image from LWIR radiation.

author: Ben321
author_rank: Frequent Contributor
timestamp: June 14, 2019, 08:27:36 pm
content: Quote from: Ultrapurple on June 12, 2019, 09:06:53 amUsing Photoshop, I combined the LWIR and MWIR image from each image pair you posted into an RGB images. LWIR is mapped to red, and MWIR is mapped to blue. Green is the average of the other 2. In other words:red=LWIRgreen=(LWIR+MWIR)/2blue=MWIRI've attached these images to this post.

author: Vipitis
author_rank: Frequent Contributor
timestamp: June 14, 2019, 09:16:22 pm
content: I am deeply interested in this topic and with QWIP it might be possible. You have an older idea of a camera that operates in both MWIR and LWIR and can switch. As we don't see those alot, there must be challanges to that design (https://apps.dtic.mil/dtic/tr/fulltext/u2/a390308.pdf).The composite dual band image you showed above as already been done as seen here:https://www.spiedigitallibrary.org/ContentImages/Journals/OPEGAR/52/6/061306/FigureImages/OE_52_6_061306_f002.pngI guess there is more to learn in military and space applications but no where close consumers.