This presentation introduces various types of lights used in machine vision applications, their important selection parameters. It also includes the basic components and a checklist of manufacturing process.

1. LightsMachine
Vision
P arth De s ai : Author

2. What is a mvL ight?
[1 ][2]
◎ Product illumination to acquire desired information
◎ Appropriate lighting component selection relates directly to
successful application deployment
◎ Software algorithm are incapable of revealing / enhancing poorly
illuminated features
2
https://www.opto-e.com/basics/light-basics [1 ]
https://www.ni.com/en-in/innovations/white-papers/1 2/a-practical-guide-to-machine-vision-lighting.html [2]
3 P rimary S election C onsiderations
Maximizethe contrast of the
features under inspection.
Minimizethe contrast of the
features of no interest
Provide Robust illumination by
getting rid of unwanted variations due
to:
Ambient light & Irrelevant components
to inspection

3. “Impact of mvLighting[3]
3
https://www.keyence.com/ss/products/vision/visionbasics/basic/illumination/ [3]

4. “Impact of mvLighting[3]
Specular Reflection Diffused Reflection
4
https://www.keyence.com/ss/products/vision/visionbasics/basic/illumination/ [3]
Transmitted Light

5. Lighting P hysics

6. S ources [1 ][2]
6

7. mvLight G eometries[2][4]
7
https://www.engatechvision.com/images/mvaposter.pdf [4]

8. Diffused Front Lighting
8
https://www.engatechvision.com/images/mvaposter.pdf [4]

9. Diffused Front Lighting
Directional Front Lighting
9
https://www.engatechvision.com/images/mvaposter.pdf [4]

10. Diffused Front Lighting
Directional Front Lighting
Polarized Front Lighting
10
https://www.engatechvision.com/images/mvaposter.pdf [4]

11. Diffused Front Lighting
Directional Front Lighting
Polarized Front Lighting
Dark Field Lighting
11
https://www.engatechvision.com/images/mvaposter.pdf [4]

12. Diffused Front Lighting
Directional Front Lighting
Polarized Front Lighting
Dark Field Lighting
Diffused Back Lighting
12
https://www.engatechvision.com/images/mvaposter.pdf [4]

13. Diffused Front Lighting
Directional Front Lighting
Polarized Front Lighting
Dark Field Lighting
Diffused Back Lighting
Polarized Back Lighting
13
https://www.engatechvision.com/images/mvaposter.pdf [4]

14. Diffused Front Lighting
Directional Front Lighting
Polarized Front Lighting
Dark Field Lighting
Diffused Back Lighting
Polarized Back Lighting
Telecentric / Collimated Back Lighting
14
https://www.engatechvision.com/images/mvaposter.pdf [4]

15. Diffused Front Lighting
Directional Front Lighting
Polarized Front Lighting
Dark Field Lighting
Diffused Back Lighting
Polarized Back Lighting
Telecentric / Collimated Back Lighting
Low Angle Lighting
15
https://www.engatechvision.com/images/mvaposter.pdf [4]

16. Diffused Front Lighting
Directional Front Lighting
Polarized Front Lighting
Dark Field Lighting
Diffused Back Lighting
Polarized Back Lighting
Telecentric / Collimated Back Lighting
Low Angle Lighting
Light Tent / Dome Light
16
https://www.engatechvision.com/images/mvaposter.pdf [4]

17. Diffused Front Lighting
Directional Front Lighting
Polarized Front Lighting
Dark Field Lighting
Diffused Back Lighting
Polarized Back Lighting
Telecentric / Collimated Back Lighting
Low Angle Lighting
Light Tent / Dome Light
Strobed Lighting
17
https://www.engatechvision.com/images/mvaposter.pdf [4]

18. Diffused Front Lighting
Directional Front Lighting
Polarized Front Lighting
Dark Field Lighting
Diffused Back Lighting
Polarized Back Lighting
Telecentric / Collimated Back Lighting
Low Angle Lighting
Light Tent / Dome Light
Strobed Lighting
18
Structured Lighting
https://www.engatechvision.com/images/mvaposter.pdf [4]

19. Diffused Front Lighting
Directional Front Lighting
Polarized Front Lighting
Dark Field Lighting
Diffused Back Lighting
Polarized Back Lighting
Telecentric / Collimated Back Lighting
Low Angle Lighting
Light Tent / Dome Light
Strobed Lighting
19
Structured Lighting
Co-Axial Lighting
https://www.engatechvision.com/images/mvaposter.pdf [4]

20. Diffused Front Lighting
Directional Front Lighting
Polarized Front Lighting
Dark Field Lighting
Diffused Back Lighting
Polarized Back Lighting
Telecentric / Collimated Back Lighting
Low Angle Lighting
Light Tent / Dome Light
Strobed Lighting
20
Structured Lighting
Co-Axial Lighting
Combined / Advanced Lighting
https://www.engatechvision.com/images/mvaposter.pdf [4]

21. Illumination E ffects [2]
21
A mail stamp - Incident under different colored lights

22. Illumination E ffects [2]
22
Candy pieces - (a) White light & Color Camera, (b) White light & Monochrome Camera, (c) Red light, (d) Red &
Green light, (e) Green light, (f) Blue light.

23. Illumination E ffects [2]
23
Bottle - Left - Illuminated with Red ring light. Bottle - Right - Illuminated with UV fluorescent light.

24. Illumination E ffects [2]
24
Glossy paper sample - Left image under diffuse white light. Right image under diffused IR light.

25. Illumination E ffects [2]
25
Assembled PCB Inspection - Left image under Red light - Right image under IR light.

26. Illumination E ffects [2]
26
A transparent plastic six-pack can holder - Left image under Red back light - Right image under Red back light
with the addition of a polarizer pair.

27. Illumination E ffects [2]
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Bottle - (a) Coaxial ring light without polarizers, (b) Coaxial ring light with polarizers (some residual glare), (c)
Off-axis (light axis parallel to the sample long axis) ring light without polarizers.

28. mvL ight S election C onsiderations [2]
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Physical Environment
• Field of View
• Working Distance
• Size of Product
• Product access restrictions /
Constraints
• Part Characteristics -
Stationary / moving
inspections
• Shocks / Vibrational impacts
• Ergonomics & Safety
Product
• Material Finish / type / texture /
color
• Reflectivity
• Geometry / Shape of Product
• Ambient / self-inflicted Light
contamination / interference
Vision System
• Lighting geometry
• Camera & Optical properties
• Features of Interest
• Additional Components - ex.
Filters
• Color of light
• Type of illumination source
• Power requirement
• Cost

29. Additional C onsiderations [1 ][2]
29
* Additional references at the end of presentation
 Wavelength
• Materials reflect / absorb wavelengths of light
differentially.
• Like colors reflect - surfaces are brightened
• Opposing colors absorb - surfaces are darkened.

30. Additional C onsiderations [1 ][2]
30
* Additional references at the end of presentation
 Wavelength
• Materials reflect / absorb wavelengths of light
differentially.
• Like colors reflect - surfaces are brightened
• Opposing colors absorb - surfaces are darkened.
 Filters
[5][6][7]
• Allows selective light transmission
• Does not have optical power
• Selective illumination, isolating wavelength,
reduce ambient noise
Absorption Filter Interference / Dichroic Filter
Polarizer FilterNeutral Density Filter

31. Additional C onsiderations [1 ][2]
31
* Additional references at the end of presentation
 Wavelength
• Materials reflect / absorb wavelengths of light
differentially.
• Like colors reflect - surfaces are brightened
• Opposing colors absorb - surfaces are darkened.
 Filters
[5][6][7]
• Allows selective light transmission
• Does not have optical power
• Selective illumination, isolating wavelength,
reduce ambient noise
 Diffuser
[8]*
• Material that diffuses or scatters light
• Transmits soft & evenly distributed light
• White surface, Glass, Teflon, Holographs, Acrylic

32. Additional C onsiderations [1 ][2]
32
* Additional references at the end of presentation
 Wavelength
• Materials reflect / absorb wavelengths of light
differentially.
• Like colors reflect - surfaces are brightened
• Opposing colors absorb - surfaces are darkened.
 Filters
[5][6][7]
• Allows selective light transmission
• Does not have optical power
• Selective illumination, isolating wavelength,
reduce ambient noise
 Diffuser
[8]*
• Material that diffuses or scatters light
• Transmits soft & evenly distributed light
• White surface, Glass, Teflon, Holographs, Acrylic
 Structured Illumination
• Projection of light with a known shading pattern
• Detect & measure deformation of pattern on scene
• Used in 3D reconstruction of objects

33. Additional C onsiderations [1 ][2]
33
* Additional references at the end of presentation
 Wavelength
• Materials reflect / absorb wavelengths of light
differentially.
• Like colors reflect - surfaces are brightened
• Opposing colors absorb - surfaces are darkened.
 Filters
[5][6][7]
• Allows selective light transmission
• Does not have optical power
• Selective illumination, isolating wavelength,
reduce ambient noise
 Diffuser
[8]*
• Material that diffuses or scatters light
• Transmits soft & evenly distributed light
• White surface, Glass, Teflon, Holographs, Acrylic
 Structured Illumination
• Projection of light with a known shading pattern
• Detect & measure deformation of pattern on scene
• Used in 3D reconstruction of objects
 Strobing / Pulsing
• Freeze the motion of fast moving objects
• Increased Life, Low power dissipation & Heating

34. L ights Manufacturing
PROCESS
• Design
• Fabrication / Machining
• Coating / Finishing
• Soldering
• Assembly
• Wiring / Cabling
• Testing & Verification
• Final Finishing
COMPONENTS
•High power LEDs
•LED Driver
•Teflon coated wire
•Multi-core cable
•Miniature connectors (M/F pair)
•Power handling / dissipating
electronics
•Aluminium Sheet / Block (For Body)
It is a good practive to have a test validation report which includes testing parameters and performance measurement metrics.
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35. Edmund
Optics
VS
Technology
CCS
Pro
Photonix
L ight Vendors
TMS Lite

36. Other R eferences
◎ https://en.wikipedia.org/wiki/Neutral-density_filter [5]
◎ https://www.olympus-lifescience.com/en/microscope-resource/primer/lightandcolor/filter/ [6]
◎ https://www.qualitymag.com/articles/91565-use-optical-filtering-to-improve-machine-vision-repeatability [7]
◎ https://en.wikipedia.org/wiki/Diffuser_(optics) [8]
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37. Thanks!
Any questions?
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