Optical Instrumentation Use Flashcards
7 cards from real ABO NOCE Basic Opticianry practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Optical Instrumentation Use flashcards as text
When using a lensometer to verify a progressive addition lens (PAL), where should the distance zone reading be taken?
Answer: At the distance reference point (DRP) marked on the lens
The distance reference point (DRP) is the designated location on a PAL where the distance power is verified with the lensometer.
A Geneva lens clock (lens measure) reads +2.00 D on the front surface and -0.75 D on the back surface of a lens. What is the approximate through power?
Answer: +1.25 D
Through power is approximated by adding the front and back surface powers: +2.00 + (-0.75) = +1.25 D.
What does a PD meter (pupillometer) primarily measure?
Answer: The interpupillary distance
A pupillometer measures the interpupillary distance (PD), which is critical for correctly placing optical centers.
When neutralizing a lens with the lensometer, the power rings are brought to sharpest focus and the lines appear broken. This indicates the presence of:
Answer: Cylinder
Broken or discontinuous lines in the lensometer eyepiece indicate the presence of cylinder (astigmatism) in the lens.
Which instrument is used to measure the base curve of a finished lens?
Answer: Geneva lens clock
The Geneva lens clock (lens measure) is used at the dispensing level to measure the surface curves of a finished lens.
A lensometer shows that a lens has 1.50 D of prism. If the dot is located below the 90° line, the prism is:
Answer: Base up
When the dot (intersection of lines) is displaced below center in the lensometer, the prism is base up in the lens.
The radiuscope is used primarily to measure:
Answer: The radius of curvature of a contact lens back surface
The radiuscope measures the radius of curvature of contact lens surfaces, particularly the back (base) curve.