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.

1. Part 3 in a Series:
Illumination Terms and Techniques
© 2014, Pete Kepf, All Rights Reserved
Pete Kepf, CVP
www.kepf.me

2. Pete Kepf, CVP
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 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
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 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
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 Motion/ Robot Guidance
 Defect/ Flaw Detection
 Inspection/ Grading/ Sorting
 Identification/ Verification
 Data Acquisition
 Measurement/ Gauging

5. Pete Kepf, CVP
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Vision Components
 Lens
 Camera
 Processor
 Input/ Output
Peripherals
 Lighting
 Frame/ Enclosure
 Controls/ Software
 Part Handling/
Reject/ Sorter

6. Pete Kepf, CVP
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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
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• High S/N
• High Contrast
• Even Distribution
• Repeatable
• Product Variability
• Ambient Conditions

8. Pete Kepf, CVP
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Light Source
 Frequency
 Brightness
 Angle
 “Shape”
 Duration
Object
 Surface
 Reflectivity
 Geometry
What do you need the image to look like?

9. Pete Kepf, CVP
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Reflection: Angle
of Incidence =
Angle of
Reflection
Absorption:
Frequency
Specific
Refraction: Affects
angle and
Frequency
Scattering: Multi-
angle Reflection

10. Pete Kepf, CVP
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Reflectivity: Polish/ Coating
Scattering: Dirt/ Scratch
Absorption: Lens Material
Refraction: Lens Material

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Reflectivity: Polish/ Coating
Scattering: Dirt/ Scratch
Absorption: Sensor Material/
Filter
Refraction: Sensor Material

12. Pete Kepf, CVP
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Back Light Pattern Projector
Line Light
Ring Light
Axial Light
Dome Light

13. Pete Kepf, CVP
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 Frequency/ Wavelength (Color)
 Polarization
 Intensity (Brightness)
 Direction (Soft/ Spectral/
Polarized)
 Duration (Constant/ Pulse)

14. Pete Kepf, CVP
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Filter Source and Camera
Source: www.thermalcamerarentals.com

15. Pete Kepf, CVP
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(Previous: Halogen- Fluorescent- Xenon; Now: LED)
Source: www.thermalcamerarentals.com
Wavelength (nanometers) = 3,000,000 / Color temp (Kelvin).

16. Pete Kepf, CVP
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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
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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
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Uses:
• Small Parts
• Structured Light

19. Pete Kepf, CVP
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Diffuse On-axis Bright/ Dark
Field

20. Pete Kepf, CVP
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21. Pete Kepf, CVP
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Shadow-less
illumination
Applications:
• specular surface
• diffused surface
General-purpose

22. Pete Kepf, CVP
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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
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Useful for:
• Robot Work
Cells
• Top Light
Assembly
• Reflective
Parts

24. Pete Kepf, CVP
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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
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Uses:
• Sphere inspection for
surface flaws
• Ball bearing inspection
• CD/DVD label
inspection
• LCD display inspection
• Automotive part
inspection

26. Pete Kepf, CVP
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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
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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
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Useful for:
• Gauging
• Measurement

29. Pete Kepf, CVP
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Seite: 29
Line Grid

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Useful for:
• Structured
Light
• Height
Derivation

31. Pete Kepf, CVP
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 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
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 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”