German Night Fighter Infrared Targeting Technology.
The "Weber Spiegel" and Membrane Radiometer invented by Paul Weber during the Third Reich era
Work on this document continues By James W. Oram, Electronic Engineer
The following text is a synopsis of the many disscussions I had with Paul Weber, a Radiation Physist in Germany during WWII. Paul and I just happened to be employed at Bell & Howell R&D Lincolnwood during the late 1980's.
(but now it is a big shopping center at Touhy & McCormick)
I worked in the Micro Imagery group for 10 years. It was here, in the R&D lab that I was assigned to work with Paul Weber for a several months.
|A side comment: I have searched the Internet to find anything like or similar to what Paul described concerning the technology of the 'Weber Spiegel' and Membrane Infrared Radiometer on Aircraft for night targeting but have not been able to find devices that match Paul's design.
There are links to "Radar Night Fighter" technology, but none to InfraRed.
So I wonder if I am the only person to which this knowledge was given?
German Night Fighter Infrared Targeting Technology would have been at the highest secrecy level.
I had to ask Paul about how they kept these things secret. Paul recounted to me that during the war the SS made it clear to all, anyone passing or leaking information would be shot no questions ask.
But as the war ended Paul had his run-ins with the SS as described later in this text.
As the many years passed, the secrecy was to no avail although.... I believe he kept it a secret all this time.
As a close co-worker in the R&D optics lab at B&H Micro Imagery Division, he confided in me many things that happen during those war years and I was interested in what he had worked on.
Diary of work:
Paul was a Radiation Physicist.
Paul worked for the German Third Reich before and during the Second World War. At that time I worked with him in the Lab at Bell & Howell in Lincolnwood north of Chicago the 80's, Paul, was in his late 70's.
I was assigned to him as an assistant for a short time while working on an optical character recognition by polarization project. During this time I had numerous conversations with him about his work in the past, especially during the Third Reich era as a leading scientist.
Paul was a man of great intellect and a brilliant scientist. With his white hair, some what balding, and with a high forehead and piercing eyes he was formidable in his ability to prosecute a project. He spoke with a German accent and even did his entire math in German, Ein, Zwei, Drie. I remember him writing notes in his log book, all in German.
His work on Infrared The Radiation wavelength Expounded on the "Air Window" that he described to me. The Membrane Radiometer and the Amplifier Explain the sensitive Membrane Radiometer whose capacitance was altered by the introduction of Infrared heat waves from Allied aircraft engines. Sensing the change by frequency shift, the system could detect and direct the pilot to guide the aircraft and weaponry to attack the Allied aircraft. The system included a high gain amplifier with a gain of 1Million, nearly un-heard of in those days.
There was a synchronous dynamo in the aircraft that provided in cockpit visual targets. Rotational Frequency 20Hz to 100 Hz, based on angular quadrant. The Mirror, the "Weber Spiegel", Will explain the concentric mirrored rings that Paul told me about.
To detect position of enemy aircraft in the flight path there were four quadrants from which the IR would come in. This was chopped up by the sychronous dynamometer into 4 frequencies ranging from 20 to 100 Cycles. (more on this later)
The Tests on German night fighters
Tests reveal that the area for sensing had to be open on the plane. Concern about drag.
I will explain as told, how the Luftwaffe Generals knew the war was over and kept changing things on the aircraft installation, delaying the full introduction of the system.
The Destruction of all his work From his office on the second story: how the SS (or possibly Gestapo) came and destroyed all his work. The allies were not far off. His discovery of Laser light, Hamburg Germany, 1941 or 1942:
First Laser Light Discovered:
As I worked with Paul in the BEG (Business Equipment Group) section of Bell & Howell in Lincolnwood, north of Chicago, Paul recounted to me one afternoon that back in Germany in 1941 he was preparing an experiment for the Infrared mirror where two glass blocks about 3 or 4 inches square and 1 inch thick that were glued face to face with a type of optical adhesive in use at that time. He had the glass block assembly sitting on his desk and early one morning (he was at work at his desk in Hamburg Germany) when the sun began to shine on his desk. As time went on the movement of the sun eventually began to shine on the glass blocks. He described to me the way he suddenly noticed a bright red light shining up high on the wall. He was puzzled at first but soon realized that it was coming from the optically thin gap in the glass blocks. He called some other colleagues to view an measure the light. He said he could tell it was a very narrow band width light but just how narrow he would soon find out. Now a team was in action trying to split the beam with a laboratory chromatic prism. Amazed they found the beam could not be split into other bands, it just remained the same narrow light band. All that is known at this time is that each glass block was some type of 'optical glass' doped with an small percentage of some elements that was to aid in some way the experiments on the infrared mirror or "Weber Spiegel" or Weber Mirror. It is believed that this dopant could have been Chromium, but still puzzlement. His Escape from the SS Near the end of the war, Paul knew his life was in great danger.
Search of Radar frequencies that could 'see' the U-Boats Snorkel
Paul recounts the tests of their radar systems to 'see' an snorkel revealed nothing. But later, after the war, in England he sees what appeared to be a Klystron radar tube but was actually a Cavity Magnetron. Apparently the Germans selected the Klystron for its more stable but lower frequency output. The Magnetron had frequency variations and drift but operated at a much higher frequency than the Klystron. Thus the Allies could 'see' smaller objects. So the German night fighter radar did not equal the Brit's radar. The Brit's had come up with a enhanced Magnetron which gave 100 times the output and a way to 'sample' the output and set the receivers to the drifting frequency thus providing a work-around for the problem and provided a workable system.
Noting: In 1935 Hans Hollmann, a German scientist, had developed a multi cavity Magnetron in Berlin.