Tektronix C-30B, Instruction Manual

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Operating Instructions—C-30B Camera
Most users of test and measurement instruments are
concerned not only w ith photographing the oscilloscope
trace but also in observing it directly. For such applications
it is important to choose a phosphor such as P2 or P31,
where the emitted light is bright enough to produce a good
w riting rate and persistence is sufficient to permit easy
viewing.
For low-sweep-rate or repetitive-sweep applications,
where a high w riting rate is not required, most phosphor
types are satisfactory. It is only for single-sweep or low-
repetition-rate applications at the fast sweep rates that
selection of a particular crt phosphor is important. In
low-repetition-rate applications at the fast sweep rates, use
of the proper phosphor can mean the difference between
getting a good photograph and not getting one at all.
Since Types P2 and P31 appear best for combined
general purpose and Photographie applications, they are
Standard on most Tektronix oscilloscopes designed for
extremely rapid sweeps. Other phosphors can be obtained
on any of the Tektronix oscilloscopes.
Table 2-1 shows the relationship between the most com-
monly used phosphors.
FILM SELECTION
For most crt reading uses, Polaroid films are likely to be
most convenient. They offer the advantages of development
in seconds to a finished dry print with wide spectral
response, good resolution, and high sensitivity. Many
different types of Polaroid film are available in packs, rolls,
and 4- by 5-inch single-sheet packets. Refer to Table 2-2 for
the films most commonly used with the C-30B Camera.
Table 2-1
Commonly-used Phosphors
Phosphor
Type
Relative
Photographie
Writing Speed3
(P11 used as
Standard)
Relative Bright­
ness Represent-
ative of 10 kV
Aluminized
Screensb
(P31 used as
Standard)
Wavelength of
Peak Radiant
Energy
(nanometers)
Decay Time
to 0.1% of
Initial Value
(ms)
Color
Fluorescence
Phosphorescence
P1
20% as fast
50% as bright 520 95 Yellowish-green
Yellowish-green
P2
40% as fast
55% as bright 510 120 Bluish-green
Yellowish-green
P7 75% as fast 35% as bright 450 1500 Blue
Yellowish-green
P11 100% 15% as bright 450 20
Purplish-blue Purplish-blue
P31 50% as fast 100% 530 32
Yellowish-green Yellowish-green
aTo achieve the writing rate comparisons the shutter of the test camera was left open five seconds to make use of the remaing phospher decay.
bTaken with a Spectra Brightness Spot Meter, which incorporates a C.I.E. Standard Eye Filter.
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