The Carl Bosch Laboratory of Berlin
Reported by:
R.H. Ranger, Lieut. Col. Sig. C., U.S.A.
B.R. Gelbaum, 2ND, Lieut. Sig. C, U.S.A.
on behalf of the
U.S. Technical Industrial Intelligence Committee
CIOS Target No. 1/659
Radar
July 10, 1945
In the fields of infra-red vision during WW II the Germany stood in the forefront. In particularly AEG was world's leading entity. We must, however, not think that research was solely concentrated by AEG, but various institutions were engaged in the many fundamental research projects. I guess, that the Allies concentrated their efforts to get night-vision apparatus as soon as possible and with the least difficulties of production. Following the typical German attitude to maximalize the vision quality - they had to put tremendous energy to obtain this goal. In about 1944 their techniques were very advanced, maybe calling for more industrial efforts. From the engineering perspective it is interesting to see how they accomplished the infra-red-vision tubes (BW-Röhre).
In order to provide as complete a picture of essential elements of infra-red telescope, a joint report on their research and manufacturing is here made.
Dr. Carl Bosch, who was very active in A.E.G. research, has perhaps the keenest insight into the theoretical side in this matter. He was come from Berlin, with a brief stage at Lehesten, to Heidelberg where he now may be found on the large family estate at 33a Schlosswolfsbrunnensweg.
In his laboratory work, he increased the receiving power greatly, down to the order of 5 mm.
Increased sensitivities were being accomplished by the use of a spongy colloid to support the Caesium photo-sensitive surface.
Sensitivities of fifty time normal have been accomplished by this process in given spots on the surface. This might be particularly useful in photocell development.
By the use of dicyaninea, sensitivity much further towards the long infra-red, was accomplished; as far as 2.4 mm. This cell was good for one week before it greatly failed; but to date it has not been duplicated.
Another by-product was the construction of a very neat high voltage source, a light compact Wimshurst machine (providing 40 kV, AOB)
To provide a reticule in the Bildwandler, Dr. Bosch projected an image of a micro-film of a sight by a small lens system directly on the front of the infra-red sensitive surface of the tube.
The relative position of the reticule and the image as picked up by the tube at a given time could not be then changed by later inaccuracy of the electron focussing.
This showed the remarkable accuracy to which the Germans were anxious to go in the use of this equipment in conjunction with flack (Flak?) firing.
Quality production of these tubes was being accomplished by the CHF Mueller (Müller, owned by Valvo or Philips, AOB) in Griez. Their process is here described.
The key personnel and test equipment are now available at Erlangen.
Dr. Frank Lohmann heads the group, and he may be located through the local Philips representative, Adolf Biegel at Nürnberger Str. 82-88 (Behelfheim) or Mr. Hans Ziegler at the large Siemens-Halske (S&H, AOB) plant.
It is believed that the best method of getting the full value out of all this work, would be to have a pilot set-up made by these people in Germany under our careful supervision.
While there may not be much direct use for Bildwandler tubes, nevertheless the technique is directly applicable to photocells.
Likewise, there may well be further direct use for infra-red equipment, especially for scientific and astronomic purpose, so it is felt that this technique should be thoroughly established, before it is dissipated.
Lieut. Gelbaum of technical Liaison, Signal Corps, cooperated in this investigation very completely.
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