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Image Tubes and Night Vision

World War II Night Vision

Grandpa worked on both the basic image tube and the associated circuitry for devices that were deployed by the Navy for secure signaling by near infrared(US/C-3 also known as RCA MI-2558), and by the Army for night-time reconnaisance(Snooperscope) and targeting(Sniperscope).  Patent number 2,506,018 with Jack Ruedy and George Morton(again) describes the tube known as the 1P25.  This tube used a photocathode sensitive to infrared radiation to form an electron image that is focused on a flourescent screen. 

A 1P25 tube is among the collection of tubes that I inherited from Grandpa, and I have since acquired and restored several of the Navy Signaling Telescopes model US/C-3 and C-3a.


1P25A flanked by 1942 tubes thought to be prototypes

The larger tube pictured above is 2 and 3/16 inches in diameter and is dated 2-7-42.  The smaller one is 1 1/2 inches in diameter and is dated 9-12-42.  The 1P25 in the center is 1 and 5/8 inch in diameter.  Each of the "prototype" tubes has 1 fewer pin than a 1P25, whose extra pin is not connected.  The larger one has a flat viewing surface, lacking the spherical lens of the 1P25 and the smaller "prototype" tube.

Developmental Metascope

The term metascope can be used generically for any device that transforms infrared images to visible ones.  This artifact was donated to the Sarnoff Library by Ron Watson, a former technician at the RCA Sarnoff Laboratory.  If I recall correctly, he got it from his father, who was also employed at the lab.
It bears the inscription MELTON MASSEY and 6914 on the outside of the frame.  Inside the frame, on the tube cradle is the inscription Peter DANON.
The vacuum tube rectifier has been replaced with a solid-state one, some of the HV wire has been covered with additional insulation(blue), and a capacitor has been replaced with a more modern one.
The objective lens is missing.

Developmental Metascope Bottom View

The bottom view of the developmental metascope shows most of the circuitry.  Between the battery tubes, at the eyepiece end is what I think is the vibrator in some sound-proofing material.  To the left of the push-button switch is the space where the rectifier tube went.  The HV transformer is at top left, and capacitors and focusing potentiometer at bottom left.

Tube from prototype metascope

The tube in the developmental metascope is identical to the one shown further above with the 1P25, with the exception that this one has the spherical correcting lens.  It is 2 and 3/16" in diameter and 6 1/2" long.  It has the initials G-L-K and the date 9-8-42 on it.  The tube socket has spring-loaded contacts that meet the ends of the pins of the tube.
Photos of developmental metascope courtesy of the David Sarnoff Library, Dr. Alex Magoun, curator.


Grandpa accompanied Naval Forces on several cruises on the Chesapeake Bay to test infrared signaling equipment.   He was given a uniform and the rank of Ensign, so that he would be protected by Naval law and treaties in the event of capture.  When asked if he felt self-conscious wearing a uniform but largely ignorant of naval customs and regulations, he said that conditions were focused more on getting the job done and so no one gave him a hard time.  I think he probably was on USS Marnell PYc-39, a converted yacht used by the Bureau of Ships for research.   He may also have been on USS Callao IX-205, a war prize (ex-Externsteine) taken from the Germans near Greenland and put into service by Bureau of ships in February 1945.

Contract with Navy for Field Testing of Signaling Gear


The US/C-3 infrared signaling telescope was designed for secure night-time signaling with infrared-filtered yardarm blinkers US/X-12 or signal searchlights, and various beacons.  For instance, an infrared beacon could be placed on a landing site by a frogman(UDT) team to guide suitably equipped vessels to the site.  The UDTs also used a retro-reflector to reveal their location for pickup by a team using active equipment.

US Navy US/C-3 Infrared Signaling Telescope, RCA MI-2558A

The US/C-3 uses large aperture optics for sensitivity, and short focal length to facilitate scanning for signals.  The optics are Schmidt-Cassegrain and are focused by removing the glass cover and inserting a slotted tool through the hole in the center of the corrector lens.  Electrical focus is by the knob on the front of the telescope, which adjusts the voltage on the focusing electrode of the 1P25 tube.

Post-war ad showing a detective keeping an eye on the "Bad Guys" with a Snooperscope

The sniperscope and snooperscope were essentially the same unit, one mounted on a pistol-type grip, and the other mounted on a carbine.  Both had an electro-optical telescope with refractive optics and a bright lamp (shown mounted below carbine) with an infrared filter.  The other unit shown in the canvas bag is the power supply.

Sniperscope mounted on a carbine

G.A. Morton and L.E. Flory, "Infrared Image Tube," Electronics, September 1946.
G.A. Morton and L. E. Flory, "An infra-red image tube and its military applications," RCA Rev., Vol. 7, pp. 385-413, 1946.
V. K. Zworykin and E. G. Ramberg, "Photoelectricity and its Application," John Wiley & Sons, New York 1949.
J. M. Fluke and N. E. Porter, "Some developments in infra-red communication components, " Proc.  Inst. Radio Engrs., Vol. 34, pp. 876-883, 1946
N.C. Beese, "Cesium vapor lamps," J. Optical Soc. Am., Vol. 36, pp 555-560, 1946.
G. E. Brown, "Military Application of Infrared Viewers," Proc. of the National Electronics Conference, Chicago, IL October 3-5, 1946.

Rob Flory

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