MKIV OPERATOR'S MANUAL
12
Jumper setting
Minimum temperature
1-2
20
°
C
2-3
10
°
C
The default setting is a minimum temperature of 20
°
C.
Zenith Pointing System
Refer to Figure 2.3 and Table 2.3
A right-angle zenith prism [ZP 1] directs incoming light from the sun, the sky, or the test lamps onto
the optical axis of the instrument. For zenith angles in the range 0
°
to 90
°
the sun, or sky, is viewed through an inclined quartz window. At zenith angle 180
°
the
spectrometer views the calibration lamps, and at - 90
°
a teflon global UV diffuser occupies the field-
of-view.
Figure 2.3: Zenith Prism Targets
Table 2.3:
Spectrometer Targets for Various Zenith Angles
Zenith angle (
°
)
Object viewed by Spectrometer
0 to 90
°
Sky or sun
180
°
Calibration lamps
-90
°
UV diffuser
The prism is mounted in a retainer which rotates in a dual-bearing system which has negligible
lateral play. . The prism is rotated by a microprocessor controlled zenith stepper motor thru a 270-
degree rotation range limited by end stops. This system provides the necessary hardware and
electronics to enable the Spectrophotometer to track the sun or moon automatically in the Zenith
angle. Automated Zenith positioning is performed by driving the Zenith Prism with a stepper motor
mounted on the front end of the foreoptics frame. The zenith-stepper motor is controlled by the
Main Electronics board.
Summary of Contents for BREWER MK IV
Page 1: ...INSTRUCTION MANUAL OM BA C230 B Mk IV...
Page 2: ...REVISION HISTORY REV DESCRIPTION DCN DATE APPD B Update 99 16 12 C Update 07 16 10...
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