Kipp & Zonen BREWER MK IV Instruction Manual page 21

Micrometer
A metric micrometer head, clamped to the spectrometer frame is used to adjust the grating rotation.
The micrometer shaft is ground to a 60 degree cone which inserts into a bearings at one end of a
floating pushrod.. A conical depression with a tetrahedral corner at the other end of the pushrod
locates a 60-degree cone mounted on the end of the grating lever arm. The pushrod is secured
between the micrometer shaft and lever arm by a tension spring. The material of the pushrod has
been selected to minimize differential temperature effects.
The micrometer is rotated by a stepper motor . The motor drives a 10-tooth gear which is
kinematically linked to a 60-tooth gear on the micrometer shaft. The drive shaft is coupled to the
motor shaft with a universal joint
One motor step represents 0.006 nm on the exit-slit plane (in the UV region). Backlash of the
micrometer and cross-spring bearing system has been measured at 0.002 nm.
Slit Mask Assembly
Refer to Table 2.4 and Figure 2.6
Located at the exit of the spectrometer is a slotted cylindrical mask which may be located in one of
eight positions Six of the eight positions allow light to enter one of the six exit slits. The second
mask position blocks light from all slits so that a dark count measurement can be made. The eighth
mask position exposes two of the exit slits so that the dead time of the photon counting system may
be determined. The correspondence between slit mask position and selected wavelength is
summarized in Table 2.4.
The axis of the cylinder is attached to the shaft of a stepper motor. The mask is aligned with the exit
slits by adjusting the vertical position of the motor and adjusting the horizontal position of the
cylinder on the motor shaft.
By rotating the slit mask, each of the mask slots aligns with a corresponding slit in the exit plane,
effectively selecting a single wavelength. During an HG test the first slot in the slit mask aligns with
the Hg calibration slit in the exit plane.
Table 2.4: slit mask position vs nominal wavelength
Slit Mask Position
Figure 2.6: Slit Mask Assembly.
18
UV Wavelength Setting (nm)
0 Hg Slit:
1 Dark Count:
2 Wavelength 1:
3 Wavelength 2:
4 Wavelength 3:
5 Wavelength 4:
6 Wavelength 5:
7 Wavelength 2 & 4 for Deadtime Test
MKIV OPERATOR'S MANUAL
303.2nm (Cal=302.1)
--------
306.3/431.4
310.1/437.3
313.5/442.8
316.8/448.1
320.1/453.2