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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

Real Test_1.jpg, grid image, freeform
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Taking a picture

Dot Chart Software - Detailed information at every point

Dot Chart Workflow

Real Test_3.png

Position #1

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Position #2

Lens orientation

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Lens at Position 3 m

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Lens at Position 3 m

Photo taken

Real Test_5.png


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Analyzed result

Single Spatial Frequency Response Plot

Analysis Results_1.png

Blue = Sagittal Spatial Frequency Response

  • Mainline = median ~ average

  • Shaded area = 10 – 90 percentile range (80% of data in this range)

  • Indicates noise/uncertainty

Red = Tangential Spatial Frequency Response

Gray = All Directions Spatial Frequency Response

  • Area and lines are percentiles:  0, 25, 50, 75, 100 %

  • Indicates overall SFR variation

  • with “slanted edge” orientation

  • Standard slanted edge analysis -> single direction only

100 = Nyquist frequency

SFR50 Color Chart

Analysis Results_2.png

The spatial frequency where a contrast of 50% (SFR=50) is reached

  • For example, when yellow turns to blue, the SFR50 frequency is exactly Nyquist/2

  • The scale is logarithmic: Crossing over one color band always doubles the frequency

  • N = Nyquist frequency = 500 um / sensor pixel pitch

Visual summary

​Worst Direction
Normally ~ TAN

~ Average SAG/TAN

​Best direction
Normally ~ SAG

​As false color image

As grayscale image

Analysis Results_3.png

Optionally it is possible to analyze optical and SMIA distortion

Analysis Results_4.png
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