Very nice new 1.5” LWIR AR Coated Germanium window available for $29 - Page 1
Forum section: electronics / general

author: Fraser
author_rank: Super Contributor
timestamp: March 03, 2020, 01:35:46 pm
content: I found a seller on eBay offering some ‘mystery’ Coherent IR “mirrors” that had been made for Inframetrics. I have bought Coherent lenses from the seller previously and they were brand new Inframetrics parts, still sealed in their wrapper.I ignored the “mirrors’ for a while, but curiosity eventually got the better of me and I bought one.Upon receiving the item I found it to be brand new and sealed. I tested it and discovered that it is not a mirror, but rather a very nice 1.5” diameter LWIR AR coated Germanium windowPlacing the window in front of a Microbolomter based LWIR camera showed it to have excellent transmission, being almost invisible while moving it into position in front of the lens ! The window is not too thick at 1.1mm so that helps keep losses and any refraction effects on the incoming energy to a minimumI immediately bought another one as they are perfect to replace damaged or corroded weather protection windows or to add to a thermal camera to protect the valuable primary lensAt the asking price I consider them a bargain as they are of superb lineage.If anyone else thinks they can make use of one, see here .....https://www.ebay.com/itm/COHERENT-FLIR-MIRROR-Germanium-Thermal-camera-LWIR-lens-protector-window-NEW-29/262845473142?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649They show only one left, but may have more stock.Transparency declaration: I provided the seller with the updated details in the title and description, for which I was kindly rewarded with the addition of a free window to my latest order.Dimensions : 1 1/2” diameter x 3/64” thickness (38.14mm x 1.1mm)Passband: 7um to 14um (LWIR)Fraser

author: Dai
author_rank: Newbie
timestamp: March 20, 2020, 05:04:31 pm
content: Thanks Fraser, I too had noticed them and dismissed them as mirrors.. Sadly I noticed your post too late but now known what to look for.As a side note, I am another new PM695 owner, the camera seems to work ok, however the view finder doesn't (ffc broken and looks to have been removed, section of a ffc in bag with camera.), neither does the visible camera. The visible camera is labelled as PAL, as is camera. Have not opened camera as yet to investigate. There may also be a power supply (external) issue, cap's likely need replacing, and also maybe in camera as well. Increase of image noise when compared to battery power, also nasty looking display occasionally when battery dies. Possible power regulation issue. I will PM you when I have a moment and at a real keyboard. The engineering port sounds interestingThanks for your wealth of knowledge and information on the subject of thermal imaging.RegardsDave

author: Fraser
author_rank: Super Contributor
timestamp: March 20, 2020, 10:25:59 pm
content: Hi Dave,Pleased to hear you got yourself a PM695I saw the auction for the camera that you bought. I rarely miss spotting a PM series camera auctionOk, to the issues with your camera......1. The EVF FFC can fail due to flexing. It can also be ripped when someone is not carefull whilst disassembling the cameraIt is a pre-formed cable but could be replaced with a straight FFC of the same pitch.2. The external power supply is a monster size for its current rating. I have yet to have one fail. The PSU can be replaced with a decent 12V 5A unit.3. The PM series do not normally misbehave when the battery is getting low. The camera works normally right up until low battery shut-down. Original batteries are mostly worn out by now and re-celled batteries are sometimes not fitted with decent quality cells. Such could cause weird issues. Test the battery bay with a decent lab power supply and see what happens as you wind the voltage down to cut-off.4. The battery and external power input use separate supply paths and operate independently of each other. The external power input has an acceptable voltage range of 11.5 to 16V @ 4A max current draw.5. The PM series have quite a complex power board. I have yet to have any problems with that board and have yet to meet a failed capacitor in one of these cameras. There is a first time for everything though.6. The visible light camera, that lives in the ‘carbuncle’ of a camera housing Cludge, is a standard composite video board camera. There is a small PCB behind it that carries out the video capture and conversion function to feed the main board with the camera output. If the camera has been dismantled (which it has) it could be that the person working on it did not reconnect the camera connector to the main PCB. You can easily test the camera outside the PM695 if desired.7. As your camera is PAL, be aware that if the RTC Powercap battery fails, your camera will default to NTSC video. That is to say, it will no longer drive or understand PAL devicesCheck the state of the RTC. If it does not retain its memory with power removed from the camera, replace the powercap that sits on top of the Dallas RTC board. Only then look at other issues ! Some may magically disappear once the RTC memory is powered by the battery8. I have stock of the Lemo 2B-310 plug fir the large I/O port. They are not exactly cheap though ! If you need one, I will see what I can do for you. The port provides the power input, RS232 TX/RX and S-Video output. The video output port uses a 0B-307 plug. I have those as wellAll the best with your investigationsFraser