got a used "thorn emi dfov" need operators manual or full specifications help - Page 1
Forum section: electronics / general

author: angelortega
author_rank: Contributor
timestamp: March 04, 2021, 03:08:32 am
content: with the post put up about dual field of view cameras, i went online to look for more of this type and found this websitehttps://www.prc68.com/I/ThermalIMagerDFOV.htmlwith some info on a "thorn emi (dual field of view) thermal imagerand pictures. by looking at the pictures i could see that the lens may come apart from the detector-display section and i was right.so i found on ebay 3 been sold, so i got one last month, "bingo" when the detector-display section is removed, i saw the lens assembly is only held by two hex screews, the eyepiece assembly is also held by two hex screews. best part is when the detector-display assembly is removed.it leaves complete empty space, where a new smaller thermal camera and lcd or oled display can be installed upgrading the "thorn emi".i will take shots and post them when i can . what i need is the user manual with the actual specs, can anybody help me

author: Vipitis
author_rank: Frequent Contributor
timestamp: March 04, 2021, 09:29:20 am
content: If it's a cooled sensor the optics will not be very fast nor even for the LWIR spectrum. So it likely won't work well with a uncooled sensor.

author: angelortega
author_rank: Contributor
timestamp: March 05, 2021, 04:37:00 pm
content: Good news optics are 8 to 12 micron clear view all the way the the spinning mirror

author: angelortega
author_rank: Contributor
timestamp: March 06, 2021, 12:51:02 am
content: now that i know this camera can be upgrade, i made a top view diagram showing how the main lens assembly is offset from the eyepiece. this diagram shows how a layout for a new core and lcd or oled screen maybe be done.in shot 6 you can see where the main lens is held by two hex nut,in shot 7 the eyepiece is held the same way.it seams that the lens and eyepiece assembles are pulled together to the cage that holds the core and they each sit on outer-case o-rings.if any body sees one of these "thon emi dfov cameras" the main lens and the eyepiece with built in cross-hair can be removed and used again in other projects.you can make a camera adapter and mount the lens on camera cores you own , or a monocular in a 3d printed case,you will have to control the internal lens with an external lever, not a big problem. in shot 4 i am trying show you how long the main optical assembly is near 165mm long. this the smallest size of the complete lens, not including the extra back focus distance to the six sided spinning mirror and then to the right angle mirror and to the sensor, that also has a lens or window. this focus path may be 200mm. now all i need to know is the nvof lens switch value. is it a x2 x3 or x4 this is why i need help finding the actual specs or operators manual. thank you everyone

author: Fraser
author_rank: Super Contributor
timestamp: March 06, 2021, 01:30:20 am
content: “As supplied”, the Thorn EMI HHTI had the following dual FOV optical specification.....20 Degrees x 8.6 Degrees (X2 magnification)8 Degrees x 3.8 Degrees (X5 magnification)It dates back to around 1984 and cost around £30K.Effective target detection range was stated as 10km (Target size not specified!)Fraser

author: Fraser
author_rank: Super Contributor
timestamp: March 06, 2021, 01:57:56 am
content: For information only, the Thorn EMI HHTI (Hand Held Thermal Imager) is a development of the Thorn EMI MRTI (Multi Role Thermal Imager) The HHTI is a weight reduced, and more compact, version of the MRTI. The MRTI was updated to operate on a Stirling Cooler later in its life but the original cooling method used bottles of high pressure pure (dry) air. This is different to the Hughes Probye system that used Argon Gas for its detector cooling. The MRTI, HHTI and Probe Eye share the same operating principle of a cooled detector viewing the output of a spinning scan mirror and that same mirror directs the light from a row of red LED ‘pixels’ towards the eyepiece. The brightness of the LED’s changes with the thermal scene content as it is scanned and so a scanned representation of the thermal scene is produced in the eyepiece. Just look up Hughes Probe Eye for more detail. I have books with pictures of the Hughes scanning system if you cannot find it detailed elsewhere.These cameras were early portable thermal imaging technology and the units had various ‘nick names’ associated with them. Amongst these were ‘Hissers’ as the air escaping from the total loss cooler made a continuous hissing sound whilst in use. Note that these units are relatively low resolution so forgiving if less than perfect optics. If the optics are used with a modern decent resolution imaging array, the shortcomings of the optics may become more apparent. That said, these were built to military standards so the Germanium optics may be an excellent specification despite the low resolution produced by the units scanning system. The only way to know is to tryFraser

author: Fraser
author_rank: Super Contributor
timestamp: March 06, 2021, 02:04:18 am
content: The Thorn EMI MRTI is detailed here (look for the ESC OASIS article) on Page 5........https://www.osti.gov/servlets/purl/485999Fraser

author: Fraser
author_rank: Super Contributor
timestamp: March 06, 2021, 02:17:32 am
content: The Hughes Probeye and images that it produced.......

author: angelortega
author_rank: Contributor
timestamp: March 06, 2021, 03:20:10 am
content: thanks fraser i was checking the net and found on ebay- euro that the gas vessels are for sale butt im not even trying to buy any of them.because the top of my thorn camera saids "4500 psi", wow real danger not something that you can just ship these days and worse the look like 1942 japan grenades and the may still have some of the gas inside ooooo THAT WILL GET CUSTOMS ATTENTION. i will sooner take the cameras core out then take any risk of this camera exploding. upgrade is a great way to recycle this assembly. i remember one story about a lot of germanium lenses recycled and destroyed that made someone sad to see. thats why i will try my tau2 320-240 my 640-480 and i also have my tamarisk 320-240 my thermaleye 160-120 and 320-240 cores. i will like to see witch of these 5 cores pixel and chip size works best to save this camera. thanks fraser