The U.S. Caliber .30 Carbines - Infrared, Sniperscopes & Equipment


The U.S. Carbine Caliber .30

- Infrared -

Sniperscopes & Equipment
















Infrared
Background
&
Overview

Sniperscope
&
Snooperscope

Model T120/M1

Sniperscope

Model M2
(Early & Late)

Sniperscope
Set No. 1, 20k volts

Model M3

Select an image to view the web page

Active Research Project that Needs Your Help

The infrared night vision scopes and equipment used with the U.S. .30 caliber carbines are an active research project. Sharing information on scopes, equipment, accessories, and documents would be greatly appreciated and help to reconstruct this history the research and documentation of which has been long overdue. Even if the information is only the data from a nameplate it gets pooled with other information from many different sources that help present the overall picture. We do the work at no cost to anyone but ourselves and present it openly via this website and it's discussion forums. Those who would like to contact us will find us on the discussion forum thread for Infrared Sniperscopes & Equipment.

Infrared Background & Overview

Infrared Basics

Of the various different types of radiation emitted by the sun the one that brings us infrared light is known as electromagnetic radiation. This is a large spectrum of energy subdivided into smaller spectrums known as radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. These are identified from one another by measuring their radiation wavelengths. The units of measurements commonly used include Angstroms (obsolete, 1 Angstrom = 0.1 nanometers or nm), Micron (1 Micron = 1000 nm), Millimeters (1 mm = 1 million nm). For simplicity, the nanometer equivalents will be used here.

Within the electromagnetic radiation spectrum, visible light ranges from about 400 nm to 700 nm. Since the infrared (IR) spectral band is much wider it's subdivided into additional groups. Exactly where within the IR spectrum these subdivisions occur and what they are called is somewhat arbitrary and can vary depending on the particular area of scientific interest. The science that includes night vision divides the IR spectrum into three basic regions.

The IR Spectrum is Divided into Three Basic Regions

Infrared viewing devices and sensors are usually limited to
a particular bandwidth within one of these three regions.
Near InfraredMid InfraredFar Infrared
Infrared Imaging
Night Vision Devices
Thermal Imaging
&
Heat Sensors
variety of electronic devices including remote controls 

Transmission of Near Infrared Radiation/Light

The transmission of Near Infrared radiation/light is affected by a number of things that can reduce it's strength and/or visibility. Examples of things that diffuse or block Near IR light includes humidity, fog, dust, and smoke. The presence and density of one or more of these impacts the distance at which Near IR light can be seen using an infrared viewer. Infrared radiation produced by the sun is mostly within the Near IR range. Think of the effects of these conditions on visible light.

The "Effective Range" of the electronics affiliated with infrared depends on the atmospheric conditions and environment present when and where the device is used. It also depends on the intended use and desired outcome. Infrared light pointed in the direction of the viewer (used for signaling, position marker, friendly force ID) can be seen at a greater distance than objects illuminated by infrared light (infrared sniperscopes).

Tests conducted by the various laboratories and military organizations were conducted under each of these conditions and in various combinations. It is important to note their estimates of the effective range were usually based on a clear night with low humidity, no obstructions, and ideal conditions. Conditions often absent in a combat environment.

The Years Leading up to World War II

U.K. scientist Sir Frederick William Herschel (1738–1822) is credited for having been the first to discover of the existence of infrared radiation on February 11th, 1800. While scientists in more than one country conducted various types of research after this discovery it wasn't until 1928 that Dutch scientists G. Holst and H. de Boer conceived the first successful means of viewing the IR spectrum using an electro-optical converter (imaging tube). They designed the first working device in 1934 while employed by Philips. The invention was given the name “Holst glass” [1].

During the 1920's and into the mid-1930's scientists from many different nations shared their infrared research and discoveries as their focus was on uses other than military. During the mid-1930's at RCA's electronic research laboratory in New Jersey Dr. Vladimir K. Zworykin and his associate, Dr. G.A. Morton developed the U.S.A.'s first infrared image tube. Dr. Zworykin had previously invented a television transmitting and receiving system employing cathode ray tubes. He was involved in the practical development of television since the early thirties. He also developed the electron microscope [2]. On 02 Jan 1936, the two scientists demonstrated their infrared image tube before a conference of the American Association for the Advancement of Science. Scientists in attendance included researchers and research teams from throughout the world.


Popular Science Magazine
March 1936
Black Light Telescope Sees In The Dark

Published two months after RCA researchers Dr. Vladimir K. Zworykin and his associate, Dr. G.A. Morton, presented
their findings before a conference of the American Association for the Advancement of Science

As the threat of Nazi Germany gained power in the mid to late 1930's governments began redirecting the focus of their scientists to the needs of their nation's military. It was well known the German scientists possessed the information, knowledge, and motivation to develop their own infrared night vision optics for use by their military. British scientists were also actively researching infrared night vision optics for use by their military.

The annexation of Austria by Germany 12 Mar 1938 prompted one of Austria's top infrared scientists, Dr. Franz Urbach, to flee Austria. Shortly thereafter Dr. Urbach joined American researchers at the Institute of Optics, University of Rochester. He was instrumental in developing infrared phosphors for the National Defense Research Committee that were used in various U.S. military infrared viewers. Including the T120/M1, M2 and M3 sniperscopes [3].

Prior to the German invasion of The Netherlands, the Dutch owners of Philips also relocated to the U.S. and assisted with infrared research and development.


World War II

The National Defense Research Committee (NDRC) was created by President Franklin Delano Roosevelt on June 27, 1940. They were created to coordinate, supervise, and conduct scientific research on the problems underlying the development, production, and use of mechanisms and devices of warfare for the United States.

The NDRC was not meant to replace the research work done by the Army and Navy in their own laboratories or through their industry contracts. Their mission was to supplement this activity by extending the research base these groups could reach out to for assistance to include the knowledge and experience of all of America's scientists. The NDRC was a scientific advisory agency and resource available to the U.S. military should they so choose.

The focus of the NDRC was limited to research and development as were any contracts they awarded. Contracts for full-scale production were the responsibility of the individual service branches.

Most of the work done by the NDRC was with the strictest secrecy as much of the research would become some of America's most important technology during World War II. To include the research and development leading to the invention and use of radar and the atomic bomb.

The NDRC was divided into various divisions based on a particular specialty. Each division was further divided into subdivisions with more specialized focus. Division 16 was responsible for Optics & Camouflage. For the infrared night vision research subdivision 16.4 Infrared often worked closely with subdivisions 16.1 Optical Instruments and 16.5 Illumination & Vision. Subdivision 16.4 included Dr. G.A. Morton from RCA.

NDRC Infrared Research

Four Main Lines of Inquiry

Infrared
Sources
The most widely used infrared source was the tungsten filament lamp.

Logically the amount of IR generated by a lamp could increase the distance at which the IR light could be seen. But the distance was also dependent on the design and construction of the viewing device.

Many varieties of tungsten lamps were furnished by General Electric to laboratories for experimental work. NDRC sponsored R & D work on lamps was conducted at the University of Michigan.
 

Near-Infrared
Transmitting Filters
Every light source that generates near infrared radiation also generates visible light. Filters that blocked visible light and allowed near-infrared to pass existed before the war. Their military value was limited due to the amount of visible light they also let pass.

NDRC sponsored R & D work on filters was conducted at the Polaroid Corporation and Ohio State University.
 

Non-Imaging
Detectors
Basically a photocell capable of receiving IR light for use with systems other than those that produced images. An example being voice communication.

Research in this area produced an electron multiplier tube that was also used for imaging (below). NDRC sponsored R & D work to develop, improve and maintain a supply of electron tubes for use by the research labs of the NDRC, Army, and Navy was assigned to Farnsworth Radio & Television Corp. in Ft. Wayne, IN.
 

Imaging
Devices
Devices to transform invisible infrared light into the shorter wavelengths of visible light.

This area of research led to the development of the sniperscopes used with the .30 caliber carbines. This is the primary focus of what follows below.
 

Infrared Imaging Devices

Design Objectives

The design of each device was directly related to one of two objectives.
Each had the ability to be used for the other objective to lesser degrees that varied.
  Device:MetascopesSniperscopes
Telescopes
  Use:signaling, or
seeing an IR beacon
detailed images
  Design:Viewing
Direct
Infrared Light
Viewing
Reflected
Infrared Light
  Pros:smaller & lighterbest images
  Cons:lacked detaillarger & heavier
  Effective Range:measured in miles
when an imaging tube was paired
with a telescope
measured in yards
All used imaging tubes
All used telescopes
All could be used to detect the presence of an enemy's infrared light.

All infrared imaging devices used a combination of an infrared-sensitive phosphor and some form of optics.


Conversion of Infrared Light to Visible Light

Infrared Sensitive Phosphors
&
Infrared Image Tubes

Infrared-Sensitive Phosphors

One way to bring about the transformation of Near IR to visible light is through the use of an infrared sensitive phosphor. Infrared sensitive phosphors store up energy when bombarded with infrared radiation. The energy is released in the form of visible light. Phosphors were a critical element in the development of infrared detection and viewing devices. Research and development before WWII had yet to produce a viable phosphor. The research team considered to be at the forefront of phosphor research before the war had been in Vienna and headed by Dr. Urbach. NDRC sponsored research and development work on infrared-sensitive phosphors was assigned to Dr. Urbach at his new job with the Institute of Optics, University of Rochester. Their research produced a number of different phosphors several of which were used with the metascopes and sniperscopes/telescopes. Additional research for applying the chemicals was assigned to Northwestern University, the Massachusetts Institute of Technology, General Electric Company, and RCA. [4],[5]

The first metascopes preceded the development of the infrared image tube using only an IR sensitive phosphor and simple viewing systems. These devices were small, lightweight, handheld, easy to transport and didn't require a power source. Their development and production continued concurrently with the larger and heavier scopes with image tubes and optics. Technology advances during and after WWII eventually allowed the smaller devices to include an image tube and improved optics.


Infrared viewing metascopes that used a phosphor without an image tube are presented on their own web
page as the focus of what follows are the infrared viewers designed to work with the image tubes.

View the Metascopes


Infrared Image Tubes

RCA's research laboratory in New Jersey where America's first image tube had been developed was contracted by the NDRC to develop an infrared tube for use in America's military infrared viewing devices. The image tube they developed and produced, designated the Model 1P25, was used in all of America's infrared viewing devices designed for use with an imaging tube during WWII. Other tubes were used in research and development but the 1P25 was the only IR imaging tube mass produced during the war. The army version of the 1P25 was designated the 1P25A with the only difference being the letter A.

The front of the image tube was coated with a radiation sensitive phosphor. As infrared radiation entered the tube it passed through a series of electrostatic fields of increasing voltage that multiplied the number of electrons. This dramatically increased the amount of infrared radiation which then bombarded an infrared sensitive phosphor that converted the infrared to visible light exiting the image tube.

Electron Multiplier Infrared Image Tube
Type 1P25A


Used by the U.S. Navy and U.S. Army during WWII
Including the Army's Model T120 Snooperscope/Sniperscope and Model M2 Sniperscope

Image tubes required a power supply capable of delivering several thousand volts. Which in turn required batteries for portable units. They also required some form of optics in line with their intended use. These items substantially increasing the weight and bulk in exchange for a much more powerful infrared viewing device and the detail needed for the Snooperscopes/Sniperscopes.

Initially, RCA was the only source for the 1P25 image tube. Production was slow and in limited quantities when the Navy was the first to contract RCA for mass-production for use in their first mass-produced infrared imaging device contracted for production in May 1943, the Type US/C-3 Model MI-2558 (see below).

Unfortunately for the Army and the deployment of their first Snooperscopes and Sniperscopes RCA's 1P25 production was already allocated to their Navy contracts when the Army awarded their first contract for the production of the T120 Snooperscopes and Sniperscopes in December 1943. While the quantity needed by the Army was minuscule in comparison to the quantities required by the Navy the Navy wanted the deployment of the Army Snooperscopes/Sniperscopes delayed and the 1P25 image tube became their means to that end. This story will be included as part of the history of the Snooperscopes/Sniperscopes.


Viewer Optics

Telescope Types used with Infrared Viewers

Viewers with a telescope used one of two simple telescope designs that were in common use at the time.
 
For Signalling and/or Detecting an IR Beacon

Used with some metascopes but not all.


This was a catadioptric optical system using a combination of refraction and
reflection via lenses (dioptrics) and curved mirrors (catoptrics). Catadioptric
combinations generally sacrifice image quality in exchange for a compact size.
 

 
For use as a Snooperscope/Sniperscope or Telescope


By reducing and/or eliminating the number of mirrors and/or glass the light encounters
before reaching the eye the in-line telescopes generally provide a better image.
Sacrificing compactness for the length that provided the better image.
 

The Infrared Viewing Devices

The NDRC assisted the Navy, Army Ordnance, Army Signal Corps and Army Engineers separately and combined with the research and development of various infrared viewing devices.

One of the first using an image tube and optics was a prototype for driving at night for U.S. Army Ordnance. Extensively tested at Fort Benning in July 1941 and at Fort Belvoir during January 1942 these were found to be partially satisfactory. But the optics provided a narrow field of view and non-stereoscopic vision. Subsequently, the Ordnance Department sponsored NDRC projects which resulted in the development of much smaller electronic image tubes suitable for use as hand-held units or for mounting on the head. This research culminated in a test of vehicle driving and gun ranging equipment at Fort Knox, Kentucky, during April 1943. As a result of these tests, the Armored Fores Board recommended that both types of equipment be considered unsuitable in their present state of development. It wasn't until after WWII that the research and technology were able to produce an acceptable device for driving at night.

The first two infrared viewing devices using an image tube and optics were contracted for production by the U.S. Navy.


Type C-1

Model M1-2548-B

     Use:   Recognition, Signals, Ranging, IR Detection   
     Telescope:   Schmidt Objective Lens   
     IR Image Tube:   1P25   
     Power Source:   BA-30 Battery, 2 ("D" cells)   
     Mount:   Handhold   
     Dimensions:   11.75" long x 8.5" wide x 5.5" high   
     Weight:   7.13 lbs   

Contracts [6]

BranchContract #QuantityManufacturerStart DateEnd DateAmount
U.S. NavyNXss 29734*unknownRCA
Camden, NJ
5/431/44$2,426,000*
    1300+      

* same contract as C-3 scope below

The Type C-1 viewer was considered the NDRC's first successful Infrared Viewing Telescope. No information has yet to be located on the quantity of C-1's produced but serial numbers exceeded 1300.

The Army Infantry Board at Ft. Benning, GA received 10 C-1 telescopes from the Navy for testing concurrent to the US/F Metascope. Serial numbers ranged from 27 to 869. The tests conducted during July 1944 concluded the C-1 had much more range than the US/F Metascope but wasn't suitable for issue to infantry troops due to its size. 01 Jan 1945 HQ Army Ground Forces advised Army Service Forces R&D a limited number had been procured and stored for use when authorized by a Theater of Operations Commander [7]. Further on the US/F Metascope is detailed on the web page devoted to the metascopes.

A nine-page users manual for the C-1 was included as Appendix A in TM 5-9340, Snooperscope & Sniperscope, dated September 1944.


The BA-30 battery is the military equivalent of the standard "D" cell battery


Type C-3

Model M1-2558

     Use:   Recognition, Signals, Ranging, IR Detection   
     Telescope:   Schmidt Objective Lens   
     IR Image Tube:   1P25   
     Power Source:   C-3:    BA-30 Battery, 2 ("D" cells)
  C-3A: 115v AC
   
     Mount:   12" Searchlight w/IR Hood, Handheld    
     Dimensions:   12" long x 5.875" wide x 9" high   
     Weight:   8 lbs   

Contracts [6]

BranchContract #QuantityManufacturerStart DateEnd DateAmount
U.S. NavyNXss 29734*unknownRCA
Camden, NJ
5/431/44$2,426,000*
U.S. NavyNObs 17472unknownRCA
Camden, NJ
10/449/45$2,363,000
U.S. NavyNObs 20951unknownRCA
Camden, NJ
5/4510/45$1,771,000
    12,500+      

* 1st contract included both the C-1 and C-3 viewers

The C-3 telescopes were the most produced and widely used infrared telescopes of any nation during WWII. The overwhelming majority on U.S. Navy ships. They were manufactured in two versions, the C-3 (battery operated) and the C3-a (115v AC). Slight improvements for the third C-3 contract designated them the Model M1-2558-A. These scopes could detect direct infrared light at distances greater than 10 miles if the atmospheric conditions allowed for it.

For signaling the C-3's were mounted to a 12" searchlight equipped for signaling. A hood (Type H) with an infrared pass filter was attached to the front of the light.


C-3 mounted to signal light with Type H infrared filter hood for demonstration purposes.

The design of the C-3 included a plate on the bottom of the device that slid in and out of a tension bracket that was bolted
to a 12" searchlight [8]. It could also be mounted to various other searchlight mounts for telescopes such as the
one shown above or on a Navy tripod.

The viewers were stowed during daylight hours. Making it difficult to find a photograph of a Naval ship with a C-3 viewer.


The U.S. Navy: Rough Waters ahead for the T120 Snooperscope & Sniperscope

A basic understanding of the Navy's use of infrared night vision devices helps to understand what took place when the Army attempted to deploy the first Snooperscopes and Sniperscopes. This short story belongs here with the Navy's infrared imaging devices with a few additional facts presented with the history of the Snooperscope/Sniperscope.

Initially, the Navy designated the code name "NAN" when referring to any of their infrared systems or related devices. This was changed to "Nancy" during WWII [9]. The Navy's first field test of an infrared viewer was the Type A Metascope for signal communications between ships and American forces on the shore during the invasion of North Africa November 8-10, 1942 [10]. While the Type A metascope was less than satisfactory by early 1944 the Navy had contracted for the production of a number of successful infrared viewing metascopes and telescopes which they were aggressively deploying for use on all of their ships in the Pacific Theater down to and including the SC class submarine chasers.

The Japanese were known not to possess the scientists with the knowledge and resources required to produce even basic infrared viewers during WWII. This allowed the U.S. Navy to communicate during darkness without the threat of Japanese detection. So long as the Japanese did not acquire one of the Navy's infrared receivers. The Germans were known to possess infrared transmitting and receiving devices which limited their widespread frequent use by Allied forces in the Atlantic, Mediterranean, and the North Sea.

In combination with IR light sources, the devices were used for night time signaling from ship to ship and ship to shore, to mark friendly ship/boat/force locations and to guide amphibious landing forces. The extent to which they were used required all ships down to submarine chasers to draw a minimum of three C-3 viewers. Carriers, battleships, and cruisers were equipped with as many as 10-12 C-3 viewers. Boats were equipped on an as needed basis [11]. Each ship was equipped with a pair of infrared beacons, a "point-of-train" light (often shortened to "train light" in addition to their IR capable 12" signal lights. The point-of-train light was usually suspended from the ship's yardarm. The beacons were mounted on or near the yardarm and oriented so as to indicate fore and aft.


IR Beacons & Point-of-Train Light

Communication was initiated via a short TBS Radio code identifying the ship for which a message was intended followed by the words "Nancy Hanks". The receiving ship would activate its point-of-train light to indicate where the ship sending the signal should train/point their infrared signal light. These beacons could also be used to send signals. By the end of the war, the larger ships were equipped with one or more beacon arrays with beacons pointed in various directions for communication with all other ships. This required each ship to use multiple C-3 viewers manned during all hours of darkness.

As the Sniperscope and Snooperscope entered production the Navy's Nancy equipment was quickly becoming their primary means of secure ship to ship communication during the hours of darkness.

References:

[1} Infrared Techniques and Electro-Optics in Russia- A History, 1946-2006, published in 2007; Chapter 1, Early Low-Light-Level and Electron-Beam Technologies, 1930–1945
[2] "New Tube Enables Seeing in the Dark", NY Times, January 3, 1936
[3] Science in World War II Series; Applied Physics: Electronics, Optics, Metallurgy by the National Defense Research Committee, 1948
[4] "An Infrared Image Tube and its Military Applications" by G. A. Morton and L. E. Flory, Research Department, RCA Laboratories Division; RCA Review Technical Journal, Sep 1946
[5] Image Forming Infrared; Summary Technical Report of Division 16, National Defense Research Committee, 1946
[6] Alphabetic Listing, Major War Supply Contracts, Cumulative, June 1940 through September 1945, Industrial Statistics Division, Civilian Production Administration, 1946
[7] Infra-Red Equipment; U.S. Army Infantry Board Report # 1595A, Fort Benning, GA, 17 Oct 1944
[8] Catalog of Naval Electronic Equipment, Supplement 1, January 1948
[9] "Nancy Hanks", C.I.C. (Combat Information Center) Magazine, Office of the Chief of Naval Operations, December 1945, p. 30-34
[10] "Infrared Signal Systems", Military Communications: From Ancient Times to the 21st Century, Christian H. Sterling, Editor, p.229-230, 2008
[11] Article 104, "NAN Signalling and Battle Identification for The Pacific Fleet", PACFLT Confidential Communication Bulletin 4 RB-44 dated 6 Dec 1944.

Next Up

Sniperscope
&
Snooperscope

Model T120/M1


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