Technical Specifications
- Camera – 9 MP USB 3.0 Color Point Grey Grashopper 3
- Imaging Lens – 5X, 0.13 NA, Olympus Plan Fluorite Infinity-Corrected Objective
- Tube Lens – Thor Labs Infinity-Corrected Tube Lens
- Illumination – Pulsed White LED, Darkfield
- Exposure Time – 10 to 60 μs
- Field of View – 2.5 mm x 2.0 mm
- Pixel Size (Object Space) – 0.74 μm
- Optical Resolution – 200 lp/mm @ 40% contrast
- Depth of Field – 20 μm @ 200 lp/mm @ 20% contrast
- High-Resolution Image Volume – 0.1 μL
- Blob-Detection Image Volume – Up to 10 μL
- Embedded System – 1.8 GHz Big-Little Quad Core ODROID-XU3, 2 GB RAM
- Image Processing – OpenCV
The image below shows the 1951 USAF resolution test chart as recorded by the SPCP2 camera. The chart features groups of line-pairs of increasing spatial frequency (decreasing distance between bars). The image shows groups 4 through 7 are being resolved by the camera with Group 7, element 5 being the spatial frequency at which the camera is no longer able to resolve the bars with sufficient contrast. Group 7, Element 5 corresponds to a spatial frequency of 203 line-pairs-per-millimeter (lp/mm) and a bar width of 2.46 μm. The line plot below confirms this result and shows that we achieve a contrast of better than 30% at 203 lp/mm.
