Optical/Laser/Vision Measurement Unit 94

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

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

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

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

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

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

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

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

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

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

Laser Scan Micrometer Highly accurate Accuracy 62 mm and repeatability of 60.15 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

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

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

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

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

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

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

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

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

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

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

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