S
(2) irradiance on the grount ia chree narrow spectral bands, ami (3) bomb
spectra versus tine.
11.3.1
Tables 11.1 and 11.2 give specific camera Jita.
Frasing Cameras
Twelve cameras were centered on expected "air zero.”
Six lé-om Fastax
cameras at 3000 to 6000 frames ptr second prowided a narrow azgle of view.
A second group of six 35-cm Fastax cameras at 2000 to 4500 frases per second
covered a wider field.
The Fastaz, a high-speed casera of the rotating prisa
type, produces discrete frame images.
With these caveras, an atte=apt was uae
to measure absolute surface brightmess in three narrow spectral bands:
4000 a,
5000 A, ami 6500 A.
11.3.2
Streak Cameras
Three 25-=> streak cameras vere operated.
These are essentially normal
Fastax cameras except that the prisms have been removed, affording a continuous
fils transport mechanism with no framing compensation.
The caneras vere fitred
with slits of the desired width to obtain necessary time resolution and expo~
sure.
Zach slit was divided into fcur segments.
To allow wery wide exposure
Fange, three segments accommodated effective neutral density 3, 2, and lL filters,
respectively.
The fourth segment remained open, giving exposure at unity.
The
three cameras were fitted with narrow-band pass filters at 3500 A, 5000 A, and
6500 A, respectively.
11.3.3
No lenses were employed with the streak cameras.
Recording Spectrograph
A Hilger lemeter quartz spectrograph was used to record spectm= versus
time during the initial phase of the detonaticn.
A 10-inch focal-length quartz
objective was used before the slit.
A fils transport mechanisa was designed and built to be accocmodated by
the Hilger instmment.
Film width of 9-1/2 inches allowed complete coverage
of the spectra which {fs available for the spectrograph.
Tbe range of the in-
strument, 2000 A to 10,000 A, exceeds the spectral sensitiviry range of the
esulsion (Eastman Kodak Tri-X Arecon Panchromatic) used.
about 16.7 psec at 100 ft/sec.
Tine resolution was
A reference marking light was e=ployed to con-
—
Cs)
SO
penssate for errors caused by fila weave.