Zeiss Axiovert 5 Instruction Manual page 58

3 Product and Functional Description | 3.5 Microscopy and Contrast Techniques
Example
a = 11 mm; b = 5 mm; λ = 550 nm; objective 20x/0.50
Attention:
§
§
Material
Copper
Gold
Silver
Bismuth
Nickel
Iron
Zinc
Platinum
Aluminum
Tin
Chrome
Coal
Graphite
Silicon
Glass
Tab. 2: Calculated phase jumps for compact material and vertical incidence of light
For a thickness measurement (step height), half the difference of the phase jump at the respective
interface must be considered:
58
If the step and its surroundings are made from different materials, the phase jumps character-
istic for the material must be considered. For all non-conducting materials, the phase jump is
180°, and for all semi-conductors only slightly different from 180°. Consequently, errors in the
step-height determination may be neglected. However, if metals on top of glass are investi-
gated, the results may become erroneous. The phase jumps given in table 2 were calculated
for vertical light incidence and compact materials. They can serve as approximate values, since
the phase jumps depend on the layerthickness and the angle of incidence of the light. An ac-
curate determination of the layer thickness is possible only when the complete sample is cov-
ered with a homogeneous layer and the path differences are measured.
If the layers and the steps are transparent, as with silicon dioxide on silicon, for example, the
interference stripes can change their colors, so that the determination of the order of the in-
terference may become problematic. This complication can be avoided if the sample is cov-
ered with a homogeneous layer.
Instruction Manual ZEISS Axiovert 5, Axiovert 5/7 materials | en-US | Rev. 6 | 431030-7011-101
Phase jump Φ
140.0°
142.5°
151.0°
151.0°
157.0°
157.5°
159.0°
160.0°
160.0°
160.5°
165.0°
160.0°
165.0°
177.0°
180.0°
ZEISS