We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
486
FREDERICK E. BARSTOW
November
a commercial electric-flash tube, shows that the energy reaches a maximum in the blue, decreases to a minimum in the near-infrared, and then increases again. The energy per 100-A band in the infrared is approximately half the energy per 100-A band in the visible. The total energy in the visible region of 4,000 to 7,000 A is only about three times the total energy in the infrared between 7,200 and 8,700 A, but this figure will vary considerably between tube types and with other circuit constants. Thus it is seen that electric-flash is an effective source of infrared light.
5000 7000 9000 10000
WAVELENGTH ANGSTROMS
Fig. 1. Spectral energy distribution for a typical flashtube; data supplied by General Electric Co.
RELATIVE SENSITIVITY -ARBITRARY UNITS TRANSMISSION -IN PER CENT SA o» oo o w Z
0 0 0 0 0 0
R
•
922 PHOTOCELL SENSITIVITY
WRATT
IN 88A ISSION
*\
Q
TRANS*
/
/^
\
/
\
i
\
/
"Xv
i
\
^
\
<
Fig. 2. Characteristics of the red-sensitive photocell and Wratten 88A filter used for measuring infrared radiation. The shaded region represents the response of the combination.
ULTRA VIOLET
INFRARED EFFICIENCIES
The spectral energy distribution of Fig. 1 is for a standard commercially available electric-flash tube used for normal black-andwhite or color photography. The question immediately arises as to the possibility of changing the tube design or operating conditions to increase the infrared output. Factors which should be investigated are voltage, capacity, tube loading, tube dimensions, gas pressure