Author Topic: AGA Thermovision 680  (Read 14101 times)

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Offline bangbang99Topic starter

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Re: AGA Thermovision 680
« Reply #25 on: June 13, 2016, 03:22:44 pm »
It seems these lenses really worth to build something around them. It is interesting to compare optical resolution of E4 lens with 680 lenses.
What about the scanning camera, I anticipate some unused potential in what can be achieved after output signal processing.
 

Offline Fraser

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Re: AGA Thermovision 680
« Reply #26 on: June 13, 2016, 03:23:09 pm »
bangbang99,

I am very impressed with your AGA 680 leneses. The large telescope is amazing but as you have found, it is quite bulky  ;D

I have a special lens for the AGA 680, namely the Thermal Microscope lens with 15X magnification  :)

It contains a visible light and thermal microscope objective. The DUT is viewed using the conventional microscope lens and eyepiece, for the purposes of alignment, and the thermal lens is then slid into position to replace the visible light lens. All very nice and it was extremely expensive new. You could easily purchase a house in the UK or USA for the cost of that lens when new. That is why I believe we are so lucky to have affordable thermal cameras now. In the past they have been limited to institutions with very deep pockets !

Pictures attached.

Fraser
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Offline Fraser

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Re: AGA Thermovision 680
« Reply #27 on: June 13, 2016, 03:37:27 pm »
bangbang99,

It pains me to say it, but the AGA 680 really is a museum piece and it is really not worth spending time or money trying to build a controller for it. The results will never justify the effort. In the AGA 680 you are seeing the era of thermal imaging in its infancy. The units size or superb build quality does not mean that it produced amazing images. It was just what was needed to produce an image that was usable. You could compare it to the early days of television and the electro-mechanical Baird Televisor. It worked, but the images were anything but impressive.

As thermal imaging detector technology improved it became possible to produce far better images without the need for scanning mirrors or prisms.

A breakthrough in portable imaging came with the manufacture of the GEC Pyroelectric Vidicon tube as found in the EEV P4428 and Argus 1 fire fighting cameras.These used a similar architecture to a conventional CCTV camera of the period and produced higher resolution images than the old AGA 680 and AGEMA 880. Things really got interesting when the FPA detector arrays became available in the form of the BST, A-Si and VOx Microbolometers. The AGA 680 looks like it came from the age of steam when compared to such recent developments.

Do not get me wrong, I love and collect the old thermal imaging cameras. it is just that I would hate for you to spend a lot of money on the AGA 680, only to find its images very disappointing.

Fraser
« Last Edit: June 13, 2016, 03:46:11 pm by Fraser »
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Offline bangbang99Topic starter

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Re: AGA Thermovision 680
« Reply #28 on: June 13, 2016, 03:48:01 pm »
AGEMA 880 is much improved version of AGA 680 in terms of everything: electronics, ergonomics, capability etc. And both these models share the same principle of operation.
What about the size of 680 optics, I think it relates to the size and sensitivity of IR detector (0.35x0.35 mm). The question is how better the optics is, concerning it was designed for such a large detector?
 

Offline bangbang99Topic starter

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Re: AGA Thermovision 680
« Reply #29 on: June 13, 2016, 03:58:05 pm »
I got this almost for nothing so don`t wait any disappointment  8) Just like to see something working :)
« Last Edit: June 13, 2016, 03:59:38 pm by bangbang99 »
 

Offline bangbang99Topic starter

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Re: AGA Thermovision 680
« Reply #30 on: June 13, 2016, 04:09:35 pm »
For the AGA 2 deg fov lens instantaneous field is 0.26 mrad which is equal to object size of 0.13 m at the distance 500 m. Field of view in this case is almost 18m.
 

Offline bangbang99Topic starter

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Re: AGA Thermovision 680
« Reply #31 on: June 13, 2016, 04:15:22 pm »
Angle of view for this lens is 35 mrad (2 degrees). 35/0.26 = 134.6 lines which is almost 128 lines of 680 system resolution.
 

Offline bangbang99Topic starter

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Re: AGA Thermovision 680
« Reply #32 on: June 13, 2016, 04:27:15 pm »
Spatial and thermal resolution description:
 

Offline Mashpriborintorg

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Re: AGA Thermovision 680
« Reply #33 on: February 15, 2017, 06:30:18 am »
I just found a AGA 680 on my local eBay, for 30 euros. missing the display / controller unit too, sadly. But comes with a 556-190-154 lens and extension ring. Usually I purchase stuff for making youtube teardowns, but it my be redundant with with topic photos and infos... however the core parts as the rotating mirors, filters disc and the sensor are not shown here, so I may take mine apart completely to reveal them
 

Offline Fraser

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Re: AGA Thermovision 680
« Reply #34 on: February 15, 2017, 12:13:07 pm »
Hi,

Good find :)

Is it a 680 or 680 LW ?

If you ever decide to rehome the lens, please let me know.

The 680 uses rotating Germanium Prisms rather than the mirrors used in later designs. It is very much a mechanical beast as that was the only way they could generate the required raster image with just a single pixel cooled photon detector. Most of what resides inside the 680 camera head is involved in spinning those two prisms at the correct speed and in sync with the required raster pattern. The detector has a simple interface and 'processing' board that feeds the signal to the controller, along with the required synchronisation signals to form a raster scan.

Fraser
If I have helped you please consider a donation : https://gofund.me/c86b0a2c
 

Offline Mashpriborintorg

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Re: AGA Thermovision 680
« Reply #35 on: February 15, 2017, 02:03:24 pm »
It is a 680, serial number 4079 according to the blurry eBay photo.
 

Offline Mashpriborintorg

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Re: AGA Thermovision 680
« Reply #36 on: February 18, 2017, 07:49:59 am »
Fraser May I re-use some of you user manual photos for a youtube video, credits provided ?
 

Offline Fraser

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Re: AGA Thermovision 680
« Reply #37 on: February 18, 2017, 09:29:23 am »
I have no objections but I do not think I posted the manual pictures ?

Fraser
If I have helped you please consider a donation : https://gofund.me/c86b0a2c
 

Offline Mashpriborintorg

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Re: AGA Thermovision 680
« Reply #38 on: February 18, 2017, 10:53:43 am »
Oops I just noticed it is actually Bangbang99, not you  :palm:
 

Offline KalleMp

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Re: AGA Thermovision 680
« Reply #39 on: February 21, 2017, 01:23:44 pm »
Hi,

This is my first post here.

I like these sorts of scanning cameras. 

Reminds me of stuff developed in South Africa by Eloptro for the military during the military sanction era when night vision devices were not available for import.  They used a hollow rotating polygonal mirror.  This scanned the view sideways across a bunch of sensors (perhaps 8-16 not sure) using the inside of the mirror. Each facet of the mirror was at an angle and they would sweep the gaps in between the sensors to multiply the scan lines by the number of facets (perhaps 6 to 16 of those).  The outside of the mirror was used to image a row of leds into the view finder optics and used eye persistence to form an image.  So it painted it in a comb fashion but used the angular and tilt alignment of the inside and outside of the hollow mirror to synchronise the sensing view with the observing view.  The mirror could be spun as fast as the sensors could handle and you could use as many sensors as you could justify price and power for.  They later went on to copy 2nd and 3rd generation channel plate image intensifiers as the night sight developments progressed.

Not sure if the following article has been mentioned here. I use Sci-hub to breach the paywall. doi:10.1117/12.958943

Dual Waveband Infrared Scanning Radiometer For Use With Rocket Motor Plumes http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=1230080

It has some nice details about the cameras. Mentions 235 kHz nominal max pixel rate.  They chose 207ksamples/s for a 60 x 90 field.  The dynamic range is or the order of 60 to 80 dB and they used a 10 bit ADC to quantise the data and save to high speed tape for later retrieval.

They mention that the fuzzy interlacing takes 6 frames to repeat and is not hard synchronised but I got the feeling that two frames would give a pretty full image.

The shutter (possibly optional) seems to be well synchronised to the vertical scanning and reflects the sensor back for a cold reference.

That is all for now.

EDIT:   
I forgot to mention that I thought it might be possible with modern sound card and super software to decode the data with just the video signal.  The slow scan TV , the HAM radio people have been doing it for a while and it might make these nice old cameras more usable if no special control box (besides PSU would be required to get data out.

Regards

Kalle
« Last Edit: February 21, 2017, 01:52:38 pm by KalleMp »
 

Offline Mashpriborintorg

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Re: AGA Thermovision 680
« Reply #40 on: February 24, 2017, 03:52:30 pm »
 
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Offline Fraser

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Re: AGA Thermovision 680
« Reply #41 on: March 05, 2017, 11:23:51 am »
Teardown video is here:

https://youtu.be/pLYQXTdspe4
If I have helped you please consider a donation : https://gofund.me/c86b0a2c
 

Offline bangbang99Topic starter

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Re: AGA Thermovision 680
« Reply #42 on: December 10, 2017, 04:57:24 pm »
Is this unit MW?
 

Offline bangbang99Topic starter

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Re: AGA Thermovision 680
« Reply #43 on: December 10, 2017, 05:01:18 pm »
This is clearly LW
 

Offline Fraser

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Re: AGA Thermovision 680
« Reply #44 on: December 10, 2017, 06:11:15 pm »
As far as I can recall, the Medium Wave 680 was marked as just '680' and the Long Wave version had the addition of 'LW' to show it to be the less common LW version. The LW version also had LW on its side casing label. The optical blocks can be simply tested using a LW thermal camera as the MW optics are opaque at LW.

Fraser
If I have helped you please consider a donation : https://gofund.me/c86b0a2c
 


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