Glass Lens Materials

Question 1

Crown Glass

Answer 1

N = 1.523 
V Value = 59 
Specific Gravity = 2.54
CVF = 1
Reflectance = 4.3%
UV Cut off = 320nm

Question 2

Key feature and Benefits of Crown Glass

Answer 2

• Excellent optics
• Low cost
• Doesnt scratch easily
• Chemical resistant

Question 3

Disadvantages of Crown Glass

Answer 3

• Heavy, brittle
• Thick for high rx
• Not impact resistant unless toughened

Question 4

1.7 Heavy Flint Glass (Zeiss Tital)

Answer 4

N = 1.706
V Value = 39.3 
Specific Gravity = 2.93
CVF = 0.74
Reflectance = 6.81% 
100% UVA protection

Question 5

1.8 Heavy Flint Glass (Zeiss Lantal)

Answer 5

N = 1.8
V value = 35.4
Specific Gravity = 3.62
CVF = 0.65
Reflectance = 8.16%
100% UVA protectoon

Question 6

1.9 Heavy Flint Glass (Zeiss Lantal)

Answer 6

N = 1.893 
V value = 30.4 
Specific Gravity = 4
CVF = 0.59 
Reflectance = 9.53% 
100% UVA Protection