The Unexpected Problem With Measuring What You Can’t Touch
From New Mind.
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This video traces the evolution of non-contact metrology, from a spider's thread inside a 17th-century telescope to laser interferometers, industrial CT and the optical frequency comb.
THE FIRST ATTEMPTS
· A spider's thread in Gascoigne's telescope led to the first micrometer in the late 1630s.
· The 1889 Prototype Metre had its defining lines engraved on the bar's neutral plane.
· Every standard was a physical object that could wear, drift or be lost.
LIGHT
· Michelson's interferometer moved one full fringe for every half wavelength of mirror travel.
· A ladder of nine etalons counted 1,553,164 cadmium wavelengths in the metre.
· In 1960 the metre was redefined as 1,650,763.73 wavelengths of krypton-86 light.
SHADOW MEASUREMENT
· WWI shells and fuses from thousands of contractors needed threads that interchanged.
· Vermont governor James Hartness and Russell Porter built a screw thread comparator.
· At fifty times magnification, a thousandth-of-an-inch flank error showed as a twentieth of an inch on the screen.
AIR AND FIELD
· Air gauging began in late-1920s France as a way to standardize carburetor jets.
· Back-pressure behind a nozzle read the gap to the part to fractions of a micron.
· Bently's garage-built eddy current probe watched turbine shafts spinning on films of oil.
THE LASER INTERFEROMETER
· A stabilized laser kept clear fringes over hundreds of meters, not a fraction of one.
· HP's 1970 5525A counted a Doppler-shifted beat frequency instead of beam brightness.
· One degree of air temperature shifts the laser's effective wavelength by about one part per million.
MACHINE VISION
· The CCD's photolithographed pixels built a precise ruler directly into the silicon.
· Cognex's first product, DataMan, read serial numbers on IBM's silicon wafers.
· Subpixel edge location found edges to a tenth of a pixel or better.
TRIANGULATION
· Meydenbauer named photogrammetry in 1867, after surveying the cathedral at Wetzlar.
· Structured light reached consumers through the Kinect and the iPhone's 30,000 projected dots.
· Kam Lau's laser tracker began as a retired interferometer on an old rotary table.
INDUSTRIAL X-RAY
· Turbine cooling passages and 3D-printed lattices hid features no probe could reach.
· Werth's 2005 TomoScope was the first CT machine built for coordinate metrology.
· Beam hardening made the centers of thick sections look less dense than they really were.
SURFACE MEASUREMENT
· Minsky invented the confocal microscope in 1955 to trace neurons in thick brain tissue.
· White-light fringes appear only where the two light paths match to within about a micron.
· Scatterometry works out chip features far smaller than Abbe's 200-nanometer limit.
THE FREQUENCY COMB
· Hall and Hänsch's comb linked light's trillions of oscillations a second to an atomic clock.
· One laser of evenly spaced colors replaced room-sized chains of specialized lasers.
· In 2009, NIST used two combs to measure absolute distance without counting fringes.
------
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https://www.patreon.com/newmind
SOCIAL MEDIA
Instagram - @newmindchannel
#metrology #engineering #precisionengineering #measurement #noncontactmetrology #manufacturing #interferometry #interferometer #Michelson #opticalflat #opticalcomparator #airgauging #eddycurrent #proximityprobe #BentlyNevada #laserinterferometer #HewlettPackard #machinevision #Cognex #CCD #photogrammetry #lasertriangulation #structuredlight #3Dscanning #lasertracker #industrialCT #computedtomography #confocalmicroscopy #whitelightinterferometry #scatterometry #frequencycomb #NIST #qualitycontrol #inspection #engineeringhistory #industrialhistory #historyoftechnology #physics
This video traces the evolution of non-contact metrology, from a spider's thread inside a 17th-century telescope to laser interferometers, industrial CT and the optical frequency comb.
THE FIRST ATTEMPTS
· A spider's thread in Gascoigne's telescope led to the first micrometer in the late 1630s.
· The 1889 Prototype Metre had its defining lines engraved on the bar's neutral plane.
· Every standard was a physical object that could wear, drift or be lost.
LIGHT
· Michelson's interferometer moved one full fringe for every half wavelength of mirror travel.
· A ladder of nine etalons counted 1,553,164 cadmium wavelengths in the metre.
· In 1960 the metre was redefined as 1,650,763.73 wavelengths of krypton-86 light.
SHADOW MEASUREMENT
· WWI shells and fuses from thousands of contractors needed threads that interchanged.
· Vermont governor James Hartness and Russell Porter built a screw thread comparator.
· At fifty times magnification, a thousandth-of-an-inch flank error showed as a twentieth of an inch on the screen.
AIR AND FIELD
· Air gauging began in late-1920s France as a way to standardize carburetor jets.
· Back-pressure behind a nozzle read the gap to the part to fractions of a micron.
· Bently's garage-built eddy current probe watched turbine shafts spinning on films of oil.
THE LASER INTERFEROMETER
· A stabilized laser kept clear fringes over hundreds of meters, not a fraction of one.
· HP's 1970 5525A counted a Doppler-shifted beat frequency instead of beam brightness.
· One degree of air temperature shifts the laser's effective wavelength by about one part per million.
MACHINE VISION
· The CCD's photolithographed pixels built a precise ruler directly into the silicon.
· Cognex's first product, DataMan, read serial numbers on IBM's silicon wafers.
· Subpixel edge location found edges to a tenth of a pixel or better.
TRIANGULATION
· Meydenbauer named photogrammetry in 1867, after surveying the cathedral at Wetzlar.
· Structured light reached consumers through the Kinect and the iPhone's 30,000 projected dots.
· Kam Lau's laser tracker began as a retired interferometer on an old rotary table.
INDUSTRIAL X-RAY
· Turbine cooling passages and 3D-printed lattices hid features no probe could reach.
· Werth's 2005 TomoScope was the first CT machine built for coordinate metrology.
· Beam hardening made the centers of thick sections look less dense than they really were.
SURFACE MEASUREMENT
· Minsky invented the confocal microscope in 1955 to trace neurons in thick brain tissue.
· White-light fringes appear only where the two light paths match to within about a micron.
· Scatterometry works out chip features far smaller than Abbe's 200-nanometer limit.
THE FREQUENCY COMB
· Hall and Hänsch's comb linked light's trillions of oscillations a second to an atomic clock.
· One laser of evenly spaced colors replaced room-sized chains of specialized lasers.
· In 2009, NIST used two combs to measure absolute distance without counting fringes.
------
SUPPORT NEW MIND ON PATREON
https://www.patreon.com/newmind
SOCIAL MEDIA
Instagram - @newmindchannel
#metrology #engineering #precisionengineering #measurement #noncontactmetrology #manufacturing #interferometry #interferometer #Michelson #opticalflat #opticalcomparator #airgauging #eddycurrent #proximityprobe #BentlyNevada #laserinterferometer #HewlettPackard #machinevision #Cognex #CCD #photogrammetry #lasertriangulation #structuredlight #3Dscanning #lasertracker #industrialCT #computedtomography #confocalmicroscopy #whitelightinterferometry #scatterometry #frequencycomb #NIST #qualitycontrol #inspection #engineeringhistory #industrialhistory #historyoftechnology #physics
