WWII British Special Forces Night Vision Technology - "TABBY" RG Receiver

In a couple of blogs I have briefly discussed the WWII vintage British Type K Monocular “TABBY” Night Vision Device, also known as the Receiver, RG (‘Red-Green’ Infrared, O.S. 960 G.A., ZA 23119), and its use by British Special Forces.

These receivers were employed by Combined Operations Pilotage Parties (COPP's) from1942-1945; contained then state-of-the-art technology, equipment was 'top secret' until March 1944. existence of  COPP's was classified under the Official Secrets Act until 1957; Ministry of Supply acceptance label is present, signed and dated 27 Apr 1944, with inspector's Stamp Crown/R86 and No. 1004; identical units extensively employed at Normandy, D-day 6 June 1944. My principal interest in the receiver is historical rather than technical, but as an engineer I had done limited work on laser designators and fire-control systems (Honeywell SEAFIRE System in late 70's).

In and amongst more recognizable weaponry is the Type K
"TABBY" RG Infrared Receiver which appears as a WWII
British water bottle with an off-set top. Click on image for
enlarged view (from author's personal collection)

As can be inferred, the receivers were employed in the night operations of the  COPPist swimmer-canoeist teams. They were principally used to aid in recovery on-board the mother Royal Navy submarines from which they had launched, following the completion of their mission in assigned operational reconnaissance areas. The submarine carried an infrared transmitter lamp (Aldis-type, but invisible to the naked eye) in the 750 - 950 nm IR wavelength, and the CV-143 receiver tube operated in the same frequency range.

The following photographs are of a WWII Mark 9 Powered Aluminum Sectional Bulkheaded Canoe where else, but in an English Garden! A similar, but simpler 'Cockle', specifically the Cockle Mk 1** was used by the COPP's. Variants were also used by the Special Boat Squadron (SBS) and Royal Marine Boom Patrol Detachment (RMBPD) swimmer- canoeists in their operations. The craft is 18 feet long and had a 28 inch beam in order to permit passage through the diameter of a submarine hatch as well as interior passageways.

WWII Mk 9 Powered Aluminum Sectional Bulkheaded Canoe;
 Note relatively large tiller and port side sponson, matched by
 a starboard sponson (not visible), for added stability in an
 ocean environment

Same craft from the bow; Note components of mast providing
 for a use  of a latin sail, weather and security conditions permitting

Lateen sail and mast assembly

Historical Background
The receiver represents the genesis in the application of infrared technology to military night vision. The primary infrared tube was first manufactured in 1939 and incorporated in this receiver as a military night vision device. It preceded the American M2 Sniperscope by four years.

In the history of war technology, this is Ground ZERO for night vision development. This British Infrared Image Tube was manufactured in 1939 for use in the SUPER SECRET "Tabby" or the OS 960 GA.ZA 23119. The world's FIRST Military "see in the dark, infrared night vision device!" This unit preceded the American M2 Sniperscope, which was first issued in 1943 by four years. Incredibly, this 65 year old electronic marvel is still functional. This is an absolutely amazing piece of technological and military history!

Various views of the Type K "TABBY" RG Receiver and
Carrying Case, showing acceptance label dated April 1944,
two months before D-Day

The ability to see in the dark, with no visible light, was a chance discovery from early Farnsworth television camera which were still in their infancy. Were the U.S. and Great Briton sharing this technology? Not likely. This was one of the most protected secrets of World War Two. It was classified "Top Secret" information. Even 10 years later in the Korean War, great secrecy surrounded the improved American M-3 Sniperscope. Strict instructions on how to destroy and bury the device were given in the technical manual so the device would not fall into enemy hands.

Night view as seen through RG Receiver using
only available light

Physical Description

The infra-red receiver tube is designated CV143 and is 41mm in height and 48mm in diameter. Operational parameters and characteristics of the tube, to extent known, are discussed below. This early technology is known as “0” generation. The tube and its battery power supply were sealed/soldered into the outer container (waterproof), which closely resembles a WWII British Army water bottle (canteen). A khaki canvas covering fastened over the unit, providing better handling in a marine environment, further conveys the impression of a water bottle. The unit weighs 3.0 pounds. The monocular eye-piece has a marked focusing adjustment with a range from '0' to about '3', but with only the numeral '2' showing, along with tick marks. Although the tube is installed in this specific unit, photographs of another disassembled tube show the serial number is hand written onto the glass with India ink. A super high tech, high voltage coating of beeswax is still on the glass barrel of the tube.

Sealed CV 143 Infrared Receiver Tube as integrated
into the type K "TABBY" RG Receiver circa 1944

Sealed CV 143 Tube showing the receiver lens

Complete Type K "TABBY" RG Receiver
unit showing resemblance to WWII British
water bottle

References to the Unit and its Employment

COMMANDOS AND RANGERS OF WORLD WAR II, J. Ladd, St. Martin's Press, New York, 1978; pp.59, 60, 62, 63, 67; SBS IN WORLD WAR II, G.B. Courtney, Hale, London, 1983; pp.5-6, 57; SBS THE INVISIBLE RAIDERS, J.D. Ladd, Arms & Armour Press, London, 1983; p.20, also see BRITISH SPECIAL FORCES, W. Seymour, Sidgwick & Jackson, London, 1985; p. 112-113 AND STEALTHILY BY NIGHT, I. Trenowden, Cercy, Midsomer Norton, Avon, 1995; p. 11, 27, 60, 62.

In STEALTHILY BY NIGHT; 'practiced launching, canoeing, swimming and recovery, camouflage and infra-red torch visibility trails. They bought privately most of the gear required and succeeded in getting two of the first infra-red transmitters and receivers in existence loaned to them. These had been produced for the RAF. Their principle is identical to the modern high-technology Infra-red light beacons, used by downed Tornado pilots in the Gulf War. Infra-red emissions, invisible to the naked eye; though visible to the pilot of a CSAR (Combat Search and Rescue helicopter) wearing night glasses. Or in the Case of the COPP RG ('Red-Green') seen through the glass of the receiver.'

In COMMANDOS AND RANGERS OF WORLD WAR II; 'RG Equipment: RG was a code name for a system of signals sent by a special lamp and received by a screen in a camera-like box. The receiving equipment included components capable of forming pictures and indicating the line of development for a gunnery night-sight, therefore the equipment was 'top secret until March 1944.'

In SBS IN WORLD WAR II: 'and the infra-red signaling gear. This RG equipment sent a beam of invisible infra-red light from an Aldis-type lamp, the signal being visible only when the beam was on a little black box-camera (actually olive-drab) with a screen, which when the beam was intercepted, showed a green spot against the speckle of green pin-pricks of infra-red light from the stars.'

Generation 0 Device Theory and Operation

Devices of this generation have so little low light amplification that as a rule more strongly, additional IR-illuminators must be used for observation. Therefore they are also called 'active night vision devices'. Basically in contrast to the other generations a transformation instead of an intensification of (IR-) light is achieved (one speaks here rather of image converter tube than an image intensifier tube). By the use of an IR-illuminator the user has mostly two crucial disadvantages: On the one hand the observation duration is depending on the usually big and heavy power source and on the other hand the user of such a strong illuminator is visible to other distant NVD-users (no real covert operations possible). The advantage of image converter tubes of the Zero Generation is a wide sensitivity in the deep infrared range (absolutely invisible illuminators can be used). The construction principle of the image converter tubes goes back into the 30's.

Structure, image converter tube:

* S-1 photocathode, coated with silver shifted cesium oxide

* Anode cone, ensures over high voltage acceleration focusing and turning the image (i. stands within the tube up-side-down)

* P1 phosphor screen, coating out of zinc and cadmium transferred phosphor

An automatic protection of the photo-sensitive tube does not exist (danger of damage with bright light, e.g. car headlights). Due to the chemical characteristics of the coatings a clear afterglow (of bright objects) is visible and the life span (service life) is limited.

If the user does not depend on the handiness of a system and do not mind their own IR recognizability, these devices are for instance well suitable for wildlife observations, although they are considered technically as outdated. The main working range of this generation is between 750 and 950 nm wavelength.

Schematic cross-section of CV 143 tube with basic
elements identified

If anyone might want additional technical data it can be found at; 

http://www.r-type.org/addtext/add074.htm. In addition please refer to another page in this same blog for an addendum to this page which describes a variant on the 'Tabby' IR receiver, the Type "CX" AN 24 A.P.W. 6815x, including detailed disassembled photographs of the receiver showing both the CV-143 tube and battery pack.