SWIR Electrophysics Micronviewer 7290A - User manual ?

[Fraser]

Hi all,

I own a very nice example of an Electrophysics Micronviewer 7290A SWIR camera

I am writing this post here, in the Thermal imaging sub forum, as this camera falls into the region between Near Infrared and MWIR thermal imaging cameras.

The 7290A uses a PbS coated Vidicon tube and has a bandwidth of 0.4um to 1.9um. It can operate as a thermal imaging camera for items with a surface temperature of 250C or higher.

These cameras are commonly used on production lines to inspect food stuff (fruit etc) and in science for imaging Laser beam shapes. The military also make use of such SWIR imaging and even use image fusion with the output of LWIR cameras.

Now that I have such a camera I will experiment with its capabilities to see just how useful, or not, the SWIR band actually is for a hobbyist.

Does anyone else own one of these cameras please ? If so, would you care to share you experiences with it here and would you have a copy of the user manual that you can share as my camera came without one.

Fraser

[Fraser]

I now have the user manual thanks to excellent support from Sofradir in the USA

Fraser

[Vipitis]

Given the vastly different spectrum of wavelengths, does this allow you to see through other stuff? Like LWIR let's you see through plastic balloons or plastic bags.

[Fraser]

Yes. An example would be its ability to image a hot object through glass or to see through visually opaque silicon wafers. SWIR works somewhat differently to MWIR and LWIR. It can image reflected photon energy. This is used to good effect when examining works of art. The art is illuminated with suitable Tungsten Halogen lamps. In some cases the artists layout pencil sketch becomes clearly visible. SWIR cameras can also image through water vapour. It has military applications due to its better imaging of some targets than thermal cameras.

Fraser

[DaJMasta]

Just picked up one of these units listed as not working myself and fancy a repair attempt.  First things first, it came with no power supply, and while the documentation I've seen says 6W and 500mA (so 12V?), I don't know what connector it uses or whether there are other rails on the other pins for it.  If you have any info it would be helpful, but I'll probably crack it open to try and power it up (and maybe replace the connector with a more standard one) in either case.


EDIT:
Well I guess I asked too soon.  Took out some screws out of curiosity and found you can just remove the whole top with the top four little screws, nice easy access.  From there I could see the power connector only had two pins soldered, and the main TO-220 voltage regulator is an LM2940 rated for 10V, so the input has to be a minimum of about 11V to turn on, so I gave it 12V on the pins on the back connector from the bench supply and it powered up just fine.  Draws about 750mA tops when starting, settles to about 550mA.  Since the connector is panel mount, I'll probably just swap it for a standard barrel jack and use a 1A rated adapter.  Easy!

I need to connect a lens (didn't ship with one) and do some testing - preliminary video output doesn't look like the sync is correct, but it's changing brightness when I put my finger in the way of the aperture, so it seems the tube is alive.  Hope to be viewing in limited SWIR in short order!

[Bill W]

Given the vastly different spectrum of wavelengths, does this allow you to see through other stuff? Like LWIR let's you see through plastic balloons or plastic bags.

Supposed to be good for seeing into 'blacked out' car windows as it goes through both glass and the black film.

Had a loan camera core once, and a loan lens, and a loan interface.  However they failed tobe with me all at the same time to use !
 

Bill

[DaJMasta]

Been working on my unit and I have yet to get good output.  I have the -E variant which is CCIR-50 output, but that seems to be recognized alright on my USB capture device, and looking at the output on a scope, I'm definitely not getting image data that it's not capturing, just all white with some noise when I mess with the lens (coupling effects, I think).

Been tracing things out to see what they are, but so far it's all red herrings.  The high voltage supply seemed to be bad, but it turns out it's just being shut down after a second or so and is actually reaching full voltage.  Traced out the feedback comparator that drives the switcher mosfet and so far, the only lines I'm seeing from it are coming from the tube board itself, so I think there's another connection - maybe a control circuit on the output of a high voltage line to the tube board, that when its switched off, the comparator turns off the HV supply.

I did add a barrel jack for power on the back, and since it was too small to use the power jack hole, I 3d printed a plug for the unused viewfinder output to fit the barrel jack and added it in.  I then noticed that my unit didn't have the piece for holding the filter in place, so I designed and 3d printed one with a retaining ring and scrounged a 1 inch 705nm long pass filter to put in there - looks great (and the black PETG it's printed in is opaque at least to 1100nm) and fits will, when I finally have a working unit I'll upload the designs.

I basically haven't touched the smaller control board yet, the larger board has the HV supply, the external sync circuits (the two DIPs towards the back of the unit), some timing generation, and even a microcontroller.  I think it has the first stage analog amp as well since the tube board only connects to this board, but I haven't yet traced it out.

Does anyone have any info on the tube itself?  It seems a few pins are basically dead shorts, but I have no experience with camera tubes, let alone ones with specialized detectors.

[Fraser]

It is a standard vidicon tube in most respects except the target material. I will see what data I have on it. Sadly I was unable to obtain any schematics for the camera from Electrophysics as they prohibit it release of such, even for older models I am aware that someone obtained a schematic for the earlier 7290 (not A) model but I do not think I managed to obtain those either. I will have to search my archives. I will see if I can help but my unit is “as new” so I have not had to work on its electronics and do not really want to poke around too much as I intend to sell it when I find a suitable buyer  These sell for serious money when working so you got yourself a bargain. From memory it is using a Hamamatsu tube.

More details to follow.

In the mean time, I recommend you search for Vidicon CCTV camera schematics, service manuals and magazine DIY camera projects from the 1970’s. These will help you better understand the needs of a avid icon tube and will provide waveform data as well. Even if you find the current fault condition, you may need to fine tune the biases on the tube due to ageing.

Fraser

[Fraser]

Sadly there is not much more in my archives to help you.

I attach the user manual in case it is of use to you.

Fraser

[Fraser]

I believe the tube used in the 7290A is a Hamamatsu N2606 as used in the Hamamatsu C2400-03 and C2741-03 IR cameras. The C2741-03 cameras datasheet may be found here.....

http://alacron.com/clientuploads/directory/Cameras/HAMAMATSU/c2741-03-Datasheet.pdf

Fraser

[Fraser]

Dage-MTI also offer a camera that uses the N2606 tube. It was a popular choice for IR and SWIR camera designs at the time.

https://dagemti.com/wp-content/uploads/2015/04/LSC70spec.pdf

Fraser

[Fraser]

An article that may be of interest......

https://museumsbau.de/wp-content/uploads/2017/12/burmester_bayerer_1993.pdf

Fraser

[Fraser]

Another document that is worth reading. It details the bias needs of the vidicon etc in Chapter 11......

http://www.r-type.org/pdfs/pctdh.pdf

Fraser

[Fraser]

The Hamamatsu N2606 IR Vidicon was discontinued back around 2008 as detailed in a quotation to be found here. Just look at how much these N2606 based cameras cost !

http://userweb.eng.gla.ac.uk/william.ward/OPTOELECTRONICS/Glasgow%20Uni%20C2741%20Quote%20220108.pdf

Fraser

[DaJMasta]

I appreciated the extra bit of library, unfortunate that there's not many discussions of driving the tube specifically in the literature directly pertaining to it!  I poked around a bit today, the 300V was a bit high so I turned it down, the -150V was a bit high but seems better now that I'm checking it again, though the -60V was -77 - which makes sense since it comes from a 2N6520 who's base is biased in the middle of 1M resistors, so I'm not really sure where 60V on the silkscreen is coming from.  Voltages that seem in the right ballpark are present at the tube (nothing in the <-40V range, but some -16V range, 450V, 415V, and 300V), and focus, definition, and alignment/centering pots do have an effect on the image, though nothing gives an actual picture - you can just adjust the black vignetting on the edges.  Adjusting the target potentiometer doesn't seem to have an effect I can see.  I see voltages on the coils, but I don't see activity, so I'm not sure there's any scanning happening - will be looking into this next.

Alarmingly, though, I found a bodge that probably wasn't done at the factory.  The positive supply for an LM358 was attached to a transistor connected from a line to the tube and then over to the other board - was hovering a little below 12V, but the trace on the board to the supply line was a 10V one which had been intentionally cut by a file.  Different kind of wire from all the other bodges on the boards, I removed it and reconnected the LM358 supply rail to an actual supply line, and the line going to the other board seems happier and it works the same.  There are a few more bodges on the boards (and at least some are definitely from the factory), so I'm hoping this won't rear up again.

Found another thread here which shows pictures of their boards.... and at least some are a different revision than mine.  Different trace layout, different part orientation.... it's probably not useful for my debugging: https://www.eevblog.com/forum/repair/electrophysics-7290a-vidicon-camera/msg744441/#msg744441

And finally, it may be really, really easy to change between CCIR-50 and RS-170 output formats... a little jumper next to the micro on the larger board.  If the board is installed normally, it's in the top left while looking at the side (lens to the left), on the side facing the tube.

[_Wim_]

Hi, just picked up an older 7290 (non A version) on Ebay. Does any one has a user manual or datasheet for this one? So far all info on the net seems to be about the 7290A, and most info for the 7290A was found right here as posted by Fraser.

The oldest page (1998) for "www.electrophysicscorp.com" found on the internet wayback machine is already about the 7290A:
https://web.archive.org/web/19980701075430/http://www.electrophysicscorp.com/prodlib/7290grp.htm

So the 7290 must be dating before that.

So far the differences between the 7290 and 7290A that I can see is that the 7290 does not have the optical filter slide, different controls and connectors at the back, and a built in power supply.

I just purchased the unit on Ebay, so it has not arrived yet. The seller has made some test with is, and it should be working (after the non working and non repairable 7215 I bought, I was now looking for a working unit...)

[_Wim_]

I also asked Lynred (which I think is the company that used to be sofradir) for the manual, so hopefully they have still something in their archive. Google has for once turned up empty handed...

[_Wim_]

I got a reply from Lynred: "Further to your request please note that LYNRED do not produce cameras but the detectors that compose cameras."

So great that they answer quickly, but unfortunately, no further assistance there.

[_Wim_]

I found a Dutch magazine from 1988 that mentions the 7290 as a new product. Unfortunately, not much technical information is provided. But nice for the archive.

Translation from Dutch:

Electrophysics has designed a micron viewer, model 7290, for detecting IR radiation from the visible range up to 1800 nm. The micron viewer consists of a TV camera with 1 inch Vidicon recording tube and a Pb O-PbS photoconductive plate.

The image that is focused on the Vidicon plate causes an increase in conductivity of the plate material, according to the intensity and the spectral response. The resulting electrical image, which is formed on the material of the plate, is read by the scanning electron beam of the camera. Some applications of the micron viewer include: detection of IR lasers and LEDs, study of semiconductor "wafer" defects, control of heat treatment processes, detection of objects at temperatures above 250 ° C, and analysis of signatures or fingerprints.

[Fraser]

I will look in my archive to see if I have anything about the 7290 model

Fraser

[Fraser]

My POC at Sofradir was Lorraine Connell in the Sales team. She tried to be as helpful as she was permitted to be.

lconnell@sofradir-ec.com

Or

el_Sales@sofradir-ec.com

That email address may redirect to her new one so worth trying ? Alternatively, send an email to the sales team with an instruction for it to be passed to Lorraine. It could just be that your email went to the wrong person on the team.

Looks like Lorraine still works fir the company.....

https://www.linkedin.com/in/lorraine-connell-a2750a17

Lorraine told me that she could not provide a schematic as Sofradir was continuing support of the Micronviewer cameras. She did supply me with a user manual however so might be able to do the same fur your earlier model.

Fraser

[Fraser]

Dr Hobbs needed a service manual but Lorraine could not help him and he is a man of some high repute who I feel sure Electrophysics would have helped, if able. Dr Hobbs may have an owners manual for his camera though. He provided contact details. I believe I contacted him in the past but he has moved on from the faulty 7290 and did not find a schematic.

https://groups.google.com/forum/m/#!topic/alt.lasers/E6Dk1nF26eU

https://alt.lasers.narkive.com/eJMl2ZhK/electrophysics-7290-ir-camera-schematic-service-manual

Fraser

[Fraser]

I can look out my 7290A user manual if you would like it.

Vidicon cameras are pretty much a standard basic architecture and unlike the Pyro Electric Vidicon thermal cameras there is no additional chopper wheel mechanics and electronics. A standard CCTV vidicon camera can be modified to work with a SWIR vidicon tube so any references detailing the design of cameras using a vidicon tube are useful in understanding the 7290 series. I suspect the 7290 uses more discrete components than the 7290A as Electrophysics likely refreshed the design using IC’s that had become available since the first generation camera was designed. This is what happened in the World of Vidicon CCTV cameras and I suspect the 7290A refresh team did similarly using CCTV camera developments as a guide to their design.

Fraser

[_Wim_]

Thanks for the info. I yesterday wrote back to the original reply from Lynred pointing to the manual of the 7290A and more thoroughly explaining what I was looking for. If this does not work out, I will try to contact  Lorraine Connell.

[_Wim_]

I have just been contacted by Lorraine Connell (my question was forwarded to her via the original contact), so she still works for Lynred. She first provided my with the user manual for the 7290A. When I explained that I was looking for the 7290, she said she will need to look when she is back in the office at the end of the week.

That is for sure excellent service for such an old unit, I which all tech companies were like that!