Quick Answer: The Spherometer-Disc Type measures the radius of curvature of lenses and mirrors using a central micrometer spindle and a 100-division circular scale, giving a least count of 0.01 mm.
Last updated: October 2026
Key Features
Central micrometer screw spindle in stainless steel
Brass/alloy disc plate with three-point perimeter contact
Vertical linear scale with 1.0 mm pitch
Circular head scale with 100 divisions
Least count 0.01 mm
Technical Specifications
Specification
Value
Mechanism
Micrometer screw with central spindle and circular scale
Material
Brass/alloy plate, stainless steel spindle
Linear scale
1.0 mm pitch
Circular scale
100 divisions, 0.01 mm
Contact points
Three-point perimeter contact
Least count
0.01 mm
HS code
9017.30
About This Product
Students rest the three contact points on a lens or mirror, bring the spindle down until it just touches the centre, and read the sagittal height from the two scales. Putting that height into the spherometer formula gives the radius of curvature, linking a hand measurement to the geometry used in optics.
Frequently Asked Questions
What is the least count of the Spherometer-Disc Type?
It is 0.01 mm: the vertical scale has a 1.0 mm pitch and the circular head carries 100 divisions.
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