simultaneously with detector output. These 

 modifications have been reported in detail by 

 Holmes and Snodgrass (1961). 



As the light energy level increases, the 

 linearity of response of the photovoltaic cell 

 is affected greatly by the external circuit 

 resistance; the response becomes more and 

 nnore linear at a given temperature as the 

 external circuit resistance approaches zero. 

 At the external circuit resistance of the order 

 of 100 ohms, as used in the present study, the 

 departure from linearity is generally not 



noticeable between 100 and 300 ^la.. output but 

 is marked at 1,000 /ia. The linearity varies 

 considerably between different cells, although 

 a given cell seems to be exceptionally stable 

 in this respect. For this reason, the linearity 

 of response up to l,000-/ja, output has been 

 determined for each cell before and after use 

 on a cruise. This linearity test is made on an 

 optical bench and with the same galvanometer 

 and cable that were used for the actual meas- 

 urements at sea. The results of such a typical 

 test are illustrated in figure 2. 



Figure 2.— Linearity of response of a Weston 856RR Photronic cell under a load of 105 t 1 ohms. 



8 



