Kipp&Zonen Brewer MkIII - Manual (Page 15)

MKIII 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° the PTFE 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. 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.