Optical Instrumentation Use Questions and Answers 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 Questions and Answers flashcards as text
A lens clock reading on the front surface of a lens shows +6.00 D and the back surface shows –2.00 D. Using a simplified calculation (n=1.53), the approximate lens power is:
Answer: +4.00 D
Using the lensmaker's equation simplified, the approximate power is the sum of the front and back surface powers: +6.00 + (–2.00) = +4.00 D.
What is the purpose of the 'nose piece' or 'lens stop' on a lensometer?
Answer: It supports and positions the lens being measured at the correct distance
The lens stop holds the spectacle lens at the precise focal distance from the lensometer's collimating lens for accurate power measurement.
Which type of lensometer reticle pattern uses a bullseye (circle with cross) target?
Answer: American Standard (ANSI) pattern
The American Standard lensometer uses a bullseye target with concentric circles and crossed lines to allow simultaneous sphere, cylinder, and prism measurement.
During lensometer verification, a lens shows 2 prism diopters base-out in the right lens. On the lensometer, this means the target is displaced:
Answer: 2 rings toward the temporal side of the reticle
Base-out prism displaces the target toward the temporal (outer) side of the reticle because prism bends light toward its base.
A PD ruler is being used to measure a patient's binocular distance PD. The ruler should be aligned:
Answer: From the center of one pupil to the center of the other pupil
PD is the distance between the centers of the two pupils and must be measured center-to-center for accurate optical alignment.
An infrared (IR) thermometer is sometimes used in optical dispensing to:
Answer: Verify the temperature of a frame warmer to prevent overheating frames
IR thermometers help opticians monitor frame heater temperatures so plastic frames are not overheated, which can cause warping, discoloration, or bubbling.
When verifying a finished pair of spectacles, the lensometer is used to check all of the following EXCEPT:
Answer: The frame's pantoscopic tilt angle
Pantoscopic tilt is a physical frame adjustment measured with a protractor or by visual assessment, not by the lensometer.