1. Optical/Laser/Vision Measurement
Unit 94

2. Objectives Define both contact measurement and non-contact measurement
Describe laser measurement and identify the equipment used for measurement
Explain scanning probe technology
List the advantages of video-measuring systems

3. Measurement: Contact or Noncontact
Contact measurement
Occurs when measuring probe:
Touches workpiece at specified points
Remains in constant contact while recording data points
Uses touch-trigger probe (TTP) method
Used on CMMs for many years
Noncontact measurement means no contact or probing of workpiece

4. Touch-Trigger Probe Method
Two dimensional (2D) head systems
Axial mode used for profiling
Radial mode used with contour surfaces
Three dimensional (3D) probing head
Used for measuring and inspecting convoluted part surfaces
Where measurements must be made with 3D movements not in machine axes movements

5. Axial-Scanning Mode
Z axis is free to move while the X and Y axes are locked

6. Radial-Scanning Mode
Z-axis is locked, and the X and Y axes are free to move

7. 3D Probe Head
Capable of simultaneously measuring in three axes – X, Y, Z

8. Optical Comparators
Light passes through condenser lens and projected against workpiece
Shadow transmitted through projecting-lens system which magnifies image and projects it onto a mirror
Image further magnified and reflected to view screen
Image compared with master form
Vernier protractor screen also available

9. Optical Comparators
Workpiece surface also checked by surface illuminator
Lights up face of workpiece, allowing image to be projected onto screen
Magnification depends on lens used
Interchangeable lenses
5X, 10X, 31.25X, 50X, 62.5X, 90X, 100X, 125X
Used on small, odd-shaped workpieces

10. Laser Measurement
Gives ability and flexibility of noncontact measuring
Proving valuable asset
Used in the following:
Manufacturing for welding, machining, heat treatment, measuring, inspection, laser marking, and bar coding

11. Laser-Tool Measurement
Allows verification of tool integrity, tool wear compensation, and all other aspects of cutting tools
Uses high-precision laser beam and photodiode for measuring operations
CNC machines uses signals generated by system following interruption of laser beam

12. Laser Scan Micrometer Highly accurate
Accuracy 62 mm and repeatability of mm
Workpiece located in center of laser beam
Creates shadow in path of scanning beam
Enables unit to determine edges of part
Uses uniform high-intensity LED (Light-Emitting Diode) light source and HL-CCD (High-speed Linear Charged-Coupled Device)
Signal digitally processed so high speed sampling at rate of 2400 samples per second

13. Laser Scan Microscope Two magnifying lenses
Located specific distance apart
Set distance from eye of observer
Light source used to illuminate sample part
Have accuracy of ½ millionth of an inch

14. Laser Surface-Finish Measurement
Permits precise, high quality measurement and verification of contours from profile
Hardware based on laser interferometric probe system
Resolution of 5 nm
Up to 150,000 measuring points captured at speeds between 0.02 mm/s and 2 mm/s
Technologies eliminate environmental influences

15. Scanning Probes Collect large amounts of data in very short time
Analyze and virtually display data
Noncontact measurement so unaffected by vibration and industrial lighting conditions
Can be used on shop floor where measurements and corrections made while workpiece still in machine

16. Reverse Engineering Ability to reproduce parts direction from samples
Parts scanned using scanning CMMs to probe surface or contour of part to be copied
Can provide hundreds of data points allowing for better quality part

17. Advantages of Video Measuring
Locate randomly oriented parts
Adapt to varying orientations, take measurements and compare them
Used for measuring, inspection, R&D, teaching and documentation
Comfortable for use over long periods since user looking at monitor
Graphical part display provided for measuring sequences

18. Video Microscope Starting to replace traditional optical microscopes
Allow image to be magnified onto large monitors or projected
Equipped with video output device which can record and permanently store digital images
Limited by magnification of current video systems

19. Video Magnifiers
Provides means of electronically enhanced optical-image magnification
Small parts with three-dimensional characteristics
Magnification range between 4X and 50X (or higher)
Black and white or in color

20. Applications Using Video Magnifiers
In-process inspection
Quality control
Examination of engineering prototypes
ISO training programs

21. Advantages of Video Magnifiers
Monitor screens provide ergonomic benefits
More than one person can view component
Reduce inspection time

22. Scanning CMMs
Simple way of automatically collecting large number of data location points
Measure or define shape of object or workpiece
Coordinate measure machine vital to inspection and measurement
Equipped with scanning heads
Digitize and create graphical part representation

23. Inspection for the Future
Trend toward nano-technology products
Smaller, lighter, and too fragile to measure with conventional mechanical contact
Noncontact scanning will provide ability to perform these operations quickly and accurately with no damage to parts