1-4
1.3 EXPLANATION OF TERMS
1.3 EXPLANATION OF TERMS
• D............................................ Diopter (a unit of measurement referring to the refractive power
of a lens; reciprocal of the focal length of the lens in meters)
• ∆ ............................................ Prism diopter (a unit of the measurement of angular deviation
of light produced by a lens)
• SPH (S) ................................. Spherical refractive power (unit: D, diopter)
• CYL (C) ................................ Cylindrical refractive power (unit: D, diopter)
• AXIS (A)............................... The position of minimum or maximum power in a lens that has
cylinder power. Axis is measured in degrees and is used to
specify the orientation of a lens to correct astigmatism. (unit:
degree)
• ADD ...................................... Additional power of a multi-focal lens (including a progressive
addition lens).
• CL ......................................... Contact lens
• HI mode ................................ Measurement mode for high index lens
• Abbe number......................... Number indicating the dispersive power of a lens. The Abbe
number of normal lenses is about 60 and that of high index
lenses ranges from approximately 30 to 45.
• PSM ...................................... Prism
To Next Page
Loading...
Need help?
General
