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Focus Variation Microscope
The Alicona™ G5 focus variation microscope is a 3D surface topography measurement instrument. Its primary purpose is to collect firearm toolmark measurements for the R&D efforts in the Forensic Toolmark Analysis Project (FTAP). The focus variation technique allows for the measurement of surface topography at much higher angles than techniques such as confocal. The instrument also has the capability of conducting 360° 3D measurements of cylindrical objects. This was utilized in a project to digitally preserve the John F Kennedy Assassination Bullet Artefacts from the National Archives. With a color camera, the microscope can generate 3D surfaces with color overlay for inspection purposes.
The Surface and Interface Metrology Group also has specialized software (Mountains Map V7) for calculating surface texture parameters (B46.1) and surface contour parameters.
Related Program Area
Specifications/Capabilities
Stage Travel (X x Y x Z): 200 mm x 200 mm x 200 mm
Objective | NA | Field of View | Lateral Pixel Spacing | Minimum Sa |
|---|---|---|---|---|
2.5 X | 0.075 | 5.63mm x 5.63 mm | 3.52 µm / px | 3.5 µm |
5 X | 0.15 | 2.82 mm x 2.82 mm | 1.76 µm / px | 0.6 µm |
10 X | 0.3 | 1.62 mm x 1.62 mm | 0.88 µm / px | 0.15 µm |
20 X | 0.4 | 810 µm x 810 µm | 0.44 µm / px | 0.075 µm |
50 X | 0.6 | 320 µm x 320 µm | 0.18 µm / px | 0.03 µm |
100 X | 0.8 | 160 µm x 160 µm | 0.09 µm / px | 0.015 µm |