NAO Actual Exam Questions
With Reviewed 100% Correct Detailed
Answers
Guaranteed Pass!!
1. Abbe number - ANSWER tells us how much chromatic aberration a lens
will produce
2. Abbe Value - ANSWER the reciprocal of the dispersive power of the lens
ranges 20-60
3. Higher the Abbe #... - ANSWER the less chromatic dispersion occurs
4. Abbe Value for:
Crown Glass
CR-39
Polycarbonate
Trivex
Hard Resin 1.67 - ANSWER Crown Glass-59
CR-39-58
,POly-29-32
Trivex-43-46
Hard Resin 1.67-32
5. Specific Gravity - ANSWER a measurement of physical density not
optical characteristic, higher the value the heavier the lens will be
6. High Velocity Impact Test - ANSWER 1/4 inch round pellet fired @ 150ft/
second, required for some safety glasses, 2.0mm lens thickness-AR coating
can reduce impact resistance
7. High Mass Impact Test - ANSWER A pointed, conical - tipped projectile
weighing 500g is dropped from 50.0 inches through onto glasses. No
thickness requirement
8. CR-39 - ANSWER pros- light weight, good optical properties, tints well
Cons- thickest material and scratches easily
9. Crown Glass - ANSWER Pros- optical clarity, resistance to scratches,
least susceptible to chemicals
Cons-heaviest material, less impact resistance
10.Trivex - ANSWER pros-ultra lightweight, UV protection in material,
excellent optics
Cons- cost and sometimes designs not available
, 11.Polycarbonate Lens - ANSWER pros- improved impact resistance, light
weight, UV protection in material
Cons- lower light transmittance, poor scratch resistance, chromatic aberration
12.Tensile Strength - ANSWER A measure of how much stress from pulling,
or tension, a material can withstand before breaking. For drill mounts and
rimless styles
13.Spherical - ANSWER surface has same power in all meridians, same
curvature from center to edge
14.Cylindrical - ANSWER 2 distinct curves of surfaces, can occur on either
front or back, curve is flat, 2 curves of diff. power
15.Aspheric - ANSWER front curvature, flattens for plus lens, steepens for
minus lens from center to edge
16.Atoric - ANSWER cylinder lens, each meridian has a diff. rate of
asphericity, minimize lens aberrations for pt. with astigmatism
17.Cellulose Acetate - ANSWER AKA Zyl or Zylonite, easy to adjust, combo
of natural and renewed sources, wide variety of colors can take two forms;
Block acetate and Acetate Granules
With Reviewed 100% Correct Detailed
Answers
Guaranteed Pass!!
1. Abbe number - ANSWER tells us how much chromatic aberration a lens
will produce
2. Abbe Value - ANSWER the reciprocal of the dispersive power of the lens
ranges 20-60
3. Higher the Abbe #... - ANSWER the less chromatic dispersion occurs
4. Abbe Value for:
Crown Glass
CR-39
Polycarbonate
Trivex
Hard Resin 1.67 - ANSWER Crown Glass-59
CR-39-58
,POly-29-32
Trivex-43-46
Hard Resin 1.67-32
5. Specific Gravity - ANSWER a measurement of physical density not
optical characteristic, higher the value the heavier the lens will be
6. High Velocity Impact Test - ANSWER 1/4 inch round pellet fired @ 150ft/
second, required for some safety glasses, 2.0mm lens thickness-AR coating
can reduce impact resistance
7. High Mass Impact Test - ANSWER A pointed, conical - tipped projectile
weighing 500g is dropped from 50.0 inches through onto glasses. No
thickness requirement
8. CR-39 - ANSWER pros- light weight, good optical properties, tints well
Cons- thickest material and scratches easily
9. Crown Glass - ANSWER Pros- optical clarity, resistance to scratches,
least susceptible to chemicals
Cons-heaviest material, less impact resistance
10.Trivex - ANSWER pros-ultra lightweight, UV protection in material,
excellent optics
Cons- cost and sometimes designs not available
, 11.Polycarbonate Lens - ANSWER pros- improved impact resistance, light
weight, UV protection in material
Cons- lower light transmittance, poor scratch resistance, chromatic aberration
12.Tensile Strength - ANSWER A measure of how much stress from pulling,
or tension, a material can withstand before breaking. For drill mounts and
rimless styles
13.Spherical - ANSWER surface has same power in all meridians, same
curvature from center to edge
14.Cylindrical - ANSWER 2 distinct curves of surfaces, can occur on either
front or back, curve is flat, 2 curves of diff. power
15.Aspheric - ANSWER front curvature, flattens for plus lens, steepens for
minus lens from center to edge
16.Atoric - ANSWER cylinder lens, each meridian has a diff. rate of
asphericity, minimize lens aberrations for pt. with astigmatism
17.Cellulose Acetate - ANSWER AKA Zyl or Zylonite, easy to adjust, combo
of natural and renewed sources, wide variety of colors can take two forms;
Block acetate and Acetate Granules
