FIGURE 1 .--COMPLETE I MAGE-ORTHI CON TELEVISION CHAIN. INDIVIDUAL UNITS 

 include: (a) CAMERA, (s) PROTECTIVE SLEEVE, (c) WATERTIGHT 

 HOUSING, (d) power supply and VOLTAGE REGULATOR, (e) CAMERA 

 CONTROL UNIT AND VIEWING MONITOR. THE OSCILLOSCOPE (f) AND 

 SMALL MONITOR (g) ARE ACCESSORY EQUIPMENT. 



1. High sensitivity, good resolution , 

 stable high-quality reproduction . 



To meet these requirements, an Image 

 Orthicon camera was chosen because it ccin 

 produce a picture of adequate quality vrith 

 as little as one-half foot-candle of illu- 

 mination. Other types, such as Vidicon or 

 C, P. S. Emitron, require considerably more 

 illumination. The disadvantages of Image 

 Orthicon equipment are greater bulk, more 

 complex circuitry, and higher cost. These 

 were accepted, however, as high sensitivity 

 is essential for observing fish under low 

 illumination without risk of changing their 

 behavior by use of artificial light. 



2. Compactness, low hydrodynamic resist - 

 ance, good stability under tow, and 

 ability to withstand pressure to 

 1,000 feet of depth . 



A cylindrical housing was chosen to 

 provide maximum compactness and low hydro- 

 dynamic resistance. A 10-inch-diameter 

 housing was used to give the unit slight 

 (about 2 pounds) positive buoyancy in water. 

 We could have used a housing of somewhat 

 smaller diameter if buoyauicy had been no 

 object. The unit weighs approximately 130 

 pounds in air. The elongated cylindrical 

 shape of the housing and detachable stabliz- 

 ing fins provide good stability under tow. 



