Bruker HYPERION, User Manual

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102 HYPERION User Manual Bruker Optik GmbH
Operation 4
This unique geometry has several advantages. Firstly, the GIR objective has a very high
throughput. Secondly, as the beam is reflected twice from the same sample surface
spot, the sample absorbs the light twice. The combination of these two factors provides
excellent sensitivity.
4.15.4 Images generated by the GIR objective
Depending on the currently set mode of operation (VIS or GIR), the GIR objective gener-
ates the following images:
• Viewing mode (VIS): Image of the sample surface (See fig. 4.6a.)
• Measurement mode (GIR): There are two images of the same sample surface
spot because the light is reflected twice from the sample surface. These two
images will be referred to as the primary image (from the first reflection) and the
secondary image (from the second reflection, after the light has been reflected
from the ellipsoidal mirror). The secondary image is both inverted and mirrored
relative to the primary image. (See fig. 4.6c.) Ideally, both images should lie one
upon the other.(See fig. 4.6b.)
➣ Note: With regard to the image generated in the viewing mode, the primary image is
mirrored and the secondary image is inverted.
Figure 4.6: a) Image of the sample surface in
VIS mode
Figure 4.6: b) Image of the measurement
spot in GIR mode - primary
image and secondary image lie
one upon the other
Figure 4.6: c) Image of the measurement
spot in GIR mode - primary
image and secondary image do
not lie one upon the other
Primary image
Secondary image