Angle Metrology

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Angle Metrology
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Angular measurement

• Angle is a ambiguous term when compared with
  concepts of length and diameter.
• The term angle is used to refer to any one of the
  following
• The angular separation of intersecting lines
• The angular spacing of points on the
  circumference of a circle
• The deviation from a reference line or plane or
  other datum
• The twist of a shaft subjected to torque.

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Units of angular measurement

• Radian
• The radian is defined as the angle subtended at
  the center of a circle by an arc equal in length
  to the radius, i.e. the angle subtended by the
  complete circumference will be 2p radians.
• Two measurement systems
• Sexagesimal system
• This system divides the right angle into 90
  degrees with the further division of the degree
  into 60 minutes and the minute into 60 seconds.
• Centesimal system
• This system divides the right angle into 100
  equal parts (grades) with a further subdivision
  of the grade into 100 minutes and the minute into
  100 seconds

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Angle measurement

• Fixed Taper gages
• Angle gage blocks
• Sine bar
• Spirit level
• Electronic level
• Optical Instruments
• Auto collimator
• Angle Dekkor

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Angle Measuring Systems and Techniques
Fixed Taper Gages
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Angle Gage Blocks
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Individual blocks in a set
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Combination of angle gages
Schematic showing the additive and the
subtractive assemblies of the same pair of angle
gage blocks
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Applications of angle blocks
Application of angle gage blocks in setting a
tiltable magnetic chuck
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Applications of angle blocks
Angle gage-block stack supporting an angular part
for the inspection of its actual angle
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Adjustable Angular Reference Bodies
Sine Bar
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Cone angle measurement
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Accuracy of Sine Bars

• The accuracy of sine bar measurement is governed
  by
• the straightness of the base generator
• the sensitivity and accuracy of the dial gage
• the magnitude of the angle being measured
• the degree of alignment of the test piece with
  the longitudinal axis of sine bar.

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Spirit level
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Electronic Levels
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Electronic Level
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Electronic Level
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Advantages of Electronic Levels

• Accuracy of settings.
• Stability.
• Speed of response.
• Remote display

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Optical Instruments
Point source of light in focal plane of a
collimating lens
Projection of a point source being reflected from
an inclined reflector
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Auto-collimator
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Angle Dekkor
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Angle Dekkor
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Circular Division