Spherometer
Product Code : SCL-PLE-11783
Quick Answer: The Spherometer is a three-legged screw gauge with a stainless steel micrometer screw, a millimetre pitch scale and a rotating circular scale, used to measure the radius of curvature of lenses and mirrors and the thickness of thin plates.
Last updated: 18 October 2026
Key Features
- Fine-threaded stainless steel screw for small vertical movements.
- Fixed vertical pitch scale graduated in millimetres.
- Large rotating circular scale for reading fractions of a turn.
- Three fixed legs with pointed hardened steel tips for stable three-point contact.
- Tapered central screw tip for judging the point of contact.
Technical Specifications
| Specification | Value |
|---|---|
| Screw | Stainless steel, fine thread |
| Vertical scale | Linear, millimetre graduations (pitch scale) |
| Circular scale | Large rotating graduated disc |
| Legs | Three fixed legs, pointed hardened steel tips |
| Central tip | Precision-tapered screw |
| Least count | Pitch ÷ number of circular scale divisions |
How It Is Used
The spherometer is set on a flat glass plate and the central screw turned until its tip just touches, giving the zero reading. It is then placed on the lens or mirror and the screw brought down to touch again. The difference between the two readings, together with the spacing of the legs, gives the radius of curvature; the same method measures the thickness of a thin plate.
Frequently Asked Questions
How is the least count of the Spherometer found?
Divide the pitch of the screw, read on the vertical millimetre scale, by the number of divisions on the circular scale.
What does the Spherometer measure?
The radius of curvature of spherical surfaces such as lenses and mirrors, and the thickness of thin plates.
Related Physics Lab Equipment
See the full physics lab equipment range, or these related measuring instruments and curved optics:
- Digital Vernier Caliper
- Vernier Calliper Stainless Steel
- Concave Lens
- Concave Mirror
- Travelling Microscope
Laboratories and education suppliers in Albania, Zimbabwe, Kyrgyzstan, Bangladesh and Cambodia can source the Spherometer from JLab India for export.
For a quotation on the Spherometer, contact JLab India on +91-8569909696.
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