1. 1171 Incident visible irradiance (to monitor ambient 



visible irradiance at surface during submarine irra- 

 diance measurements) (62) 



Range and accuracy: 



to 1 g. cal. /cm. ^/min. ±0.1% (for visible light 

 only) 

 Specifications and requirements: 



(1) Remote controlled filter -changing mechanism. 



(2) Equipped with a cosine collector. 



(3) Gimbal-mounted. 



Operating environment: Exposed marine atmosphere, 

 tropical to polar. 



1. 1172 Ambient irradiance (to measure visible irradiance in 



situ at depth) (73) 



Range and accuracy: 



0.001 to l.lg. cai./cm. /min. ±2% at depths 



to 500 m. 

 Specifications and requirements: 



(1) Detectors shall be provided with cosine collec- 

 tors and be capable of being oriented in any 

 direction. 



(2) Provision in some designs to measure the 

 spectral distribution of light. 



Operating environment: -2° to 45 C. 



1. 1173 Beam Transmission (to measure the absorption and 



scattering of light in water). (207) 



Range and accuracy: 



to 100%/m. ±0.05% at all wave lengths. 

 Specifications and requirements: 



(1) Capable of employing a variety of interference- 

 type filters which may be changed while sub- 

 merged. 



(2) Capable of operation in full sunlight. 



(3) Design to provide adequate flushing when in 

 motion. 



(4) Can be towed up to 15 knots. 



(5) Path lengths adjustable (a) 5 to 50 cm. 

 (b) 50 to 200 cm. 



1. 1180 Current (2 modules). 



Range and accuracy: 



425 



