Fundamentals of Machine Vision- Lighting
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The document discusses lighting techniques for machine vision. It covers various lighting applications including motion guidance, defect detection, inspection and sorting. Key components of vision systems like lenses, cameras and lighting are described. Different lighting setups are discussed including front, back and structured lighting. Factors that impact lighting design like frequency, brightness and duration are also summarized.
Fundamentals of Machine Vision- Lighting
- 1. Part 3 in a Series: Illumination Terms and Techniques 息 2014, Pete Kepf, All Rights Reserved Pete Kepf, CVP www.kepf.me
- 2. Pete Kepf, CVP www.kepf.me Overview: Lighting is critical variable Applications and their lighting schemes Lighting Lenses Sensors What do you want your image to look like? Software Part Attributes
- 3. Pete Kepf, CVP www.kepf.me Machine Vision is the use of a computer to acquire visual information and/or extract image information for purposes of data storage or automatic decision making.
- 4. Pete Kepf, CVP www.kepf.me Motion/ Robot Guidance Defect/ Flaw Detection Inspection/ Grading/ Sorting Identification/ Verification Data Acquisition Measurement/ Gauging
- 5. Pete Kepf, CVP www.kepf.me Vision Components Lens Camera Processor Input/ Output Peripherals Lighting Frame/ Enclosure Controls/ Software Part Handling/ Reject/ Sorter
- 6. Pete Kepf, CVP www.kepf.me Motion: Front Lighting Near IR Flaw: Front Lighting Blue Filter Measurement Back Lighting Visible Sort: Front Diffuse Visible Measurement Structured Pattern Projector Count Front Line Visible
- 7. Pete Kepf, CVP www.kepf.me High S/N High Contrast Even Distribution Repeatable Product Variability Ambient Conditions
- 8. Pete Kepf, CVP www.kepf.me Light Source Frequency Brightness Angle Shape Duration Object Surface Reflectivity Geometry What do you need the image to look like?
- 9. Pete Kepf, CVP www.kepf.me Reflection: Angle of Incidence = Angle of Reflection Absorption: Frequency Specific Refraction: Affects angle and Frequency Scattering: Multi- angle Reflection
- 10. Pete Kepf, CVP www.kepf.me Reflectivity: Polish/ Coating Scattering: Dirt/ Scratch Absorption: Lens Material Refraction: Lens Material
- 11. Pete Kepf, CVP www.kepf.me Reflectivity: Polish/ Coating Scattering: Dirt/ Scratch Absorption: Sensor Material/ Filter Refraction: Sensor Material
- 12. Pete Kepf, CVP www.kepf.me Back Light Pattern Projector Line Light Ring Light Axial Light Dome Light
- 13. Pete Kepf, CVP www.kepf.me Frequency/ Wavelength (Color) Polarization Intensity (Brightness) Direction (Soft/ Spectral/ Polarized) Duration (Constant/ Pulse)
- 14. Pete Kepf, CVP www.kepf.me Filter Source and Camera Source: www.thermalcamerarentals.com
- 15. Pete Kepf, CVP www.kepf.me (Previous: Halogen- Fluorescent- Xenon; Now: LED) Source: www.thermalcamerarentals.com Wavelength (nanometers) = 3,000,000 / Color temp (Kelvin).
- 16. Pete Kepf, CVP www.kepf.me Lumens vs. Lux: 1 lx = 1 lm/m2 Lumen = Light Emitted Total "amount" of visible light in a defined beam or angle, or emitted from a source. Also depends on its spectrum, via the nominal response of the human eye. Lux = Area Accounts for the area over which the lumens are dispersed. 1000 lumens, concentrated into an area of one square meter provides an illuminance of 1000 lux. The same 1000 lumens, spread out over ten square meters, produces a dimmer illuminance of only 100 lux. Source: Wikipedia
- 17. Pete Kepf, CVP www.kepf.me Seite: 17 Top (or Front) Light source and image sensor are on the same side of the part. Diffuse On-axis Dark/ Bright Field Back Light source and image sensor are on opposite sides of the part. Diffuse Collimated Structured Light source has a known geometry. Line Grid
- 18. Pete Kepf, CVP www.kepf.me Uses: Small Parts Structured Light
- 19. Pete Kepf, CVP www.kepf.me Diffuse On-axis Bright/ Dark Field
- 21. Pete Kepf, CVP www.kepf.me Shadow-less illumination Applications: specular surface diffused surface General-purpose
- 22. Pete Kepf, CVP www.kepf.me Applications imaging web line scan Features adjustable lens enhanced cooling low current consumption Uses Road surface inspection Bottle inspection Carpet Inspection Print Inspection
- 23. Pete Kepf, CVP www.kepf.me Useful for: Robot Work Cells Top Light Assembly Reflective Parts
- 24. Pete Kepf, CVP www.kepf.me Uses: Metal and chromed bearing surface inspection CD / DVD assembly inspection Package inspection of glossy plastics and finishes Inspection of metal stampings and parts with electrical contacts Automotive applications Medical device packaging and tray packs Pharmaceuticals blister form fill and trim Cosmetics and makeup packaging equipment and lines Diffused Tube Lights are meant for inspecting elongated parts Metal and chromed bearing surface inspection Image of Sphere
- 25. Pete Kepf, CVP www.kepf.me Uses: Sphere inspection for surface flaws Ball bearing inspection CD/DVD label inspection LCD display inspection Automotive part inspection
- 26. Pete Kepf, CVP www.kepf.me Uses Illumination of scratches on reflective surfaces Ball grid array (BGA) inspection Water contamination inspection Bottle Cap inspection Microscopic stage illumination Inspect molded epoxy parts to uncover imperfections such as cracks, bubbles, and structural damage
- 27. Pete Kepf, CVP www.kepf.me Diffuse Collimated Uses: Absence/presence of objects Defect detection in glass/plastic containers Object tracking (Fish in aquarium) PCB (printed circuit board) board assembly through-hole lead detection Web inspection (pin-holes in web) Bottle cap detection Bolt/Bolt thread inspection Glass Sheet defect detection Sub-pixel dimensional inspection
- 28. Pete Kepf, CVP www.kepf.me Useful for: Gauging Measurement
- 29. Pete Kepf, CVP www.kepf.me Seite: 29 Line Grid
- 30. Pete Kepf, CVP www.kepf.me Useful for: Structured Light Height Derivation
- 31. Pete Kepf, CVP www.kepf.me Constant Non-Moving Parts Use Care with Ambient Typically large area No Controller > 10 microseconds Line Speeds up to 1200 parts/ minute LED with Controller Configurable Form Factor > 100 nanoseconds Part speeds up to 3500 feet/ second LED with Controller Configurable Form Factor
- 32. Pete Kepf, CVP www.kepf.me Goals: High S/N High Contrast Even Distribution Repeatable Variables Frequency Brightness Angle Shape Duration Other Components Lens Camera Sensor Some Lighting Terms Top/ Front Back Structured On-axis Diffuse Lighting W