Dot Chart Image Testing Software
Dot Chart Software to estimate the image quality of lens assembling during mass production
Dot Chart Testing Software
Compared to conventional MTF testers the main benefit is the comprehensiveness of the image quality check, full transparency as to how image quality is calculated, and the ability to customize it based on the customer’s needs
Taking a picture
Dot Chart Software - Detailed information at every point
Dot Chart Workflow
Position #1
Position #2
Lens orientation
Lens at Position 3 m
Lens at Position 3 m
Photo taken
Failed
Pass
Analyzed result
Single Spatial Frequency Response Plot
Blue = Sagittal Spatial Frequency Response
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Mainline = median ~ average
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Shaded area = 10 – 90 percentile range (80% of data in this range)
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Indicates noise/uncertainty
Red = Tangential Spatial Frequency Response
Gray = All Directions Spatial Frequency Response
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Area and lines are percentiles: 0, 25, 50, 75, 100 %
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Indicates overall SFR variation
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with “slanted edge” orientation
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Standard slanted edge analysis -> single direction only
100 = Nyquist frequency
SFR50 Color Chart
The spatial frequency where a contrast of 50% (SFR=50) is reached
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For example, when yellow turns to blue, the SFR50 frequency is exactly Nyquist/2
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The scale is logarithmic: Crossing over one color band always doubles the frequency
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N = Nyquist frequency = 500 um / sensor pixel pitch
Visual summary
Worst Direction
Normally ~ TAN
Median
~ Average SAG/TAN
Best direction
Normally ~ SAG
As false color image
As grayscale image
Optionally it is possible to analyze optical and SMIA distortion
