Refractive Index | The University Of Western Ontario

University:
The University Of Western Ontario
Course:
ANATCELL 3309 | Mammalian Histology
Academic year:

2022
Views:

354

Pages:

2
Author:

Kyuwon J.

Transmission ● Lens must be clear as possible ● All light in interaction with the front portion of lens must fully penetrate the lens completely ○ Theoretically possible but cannot happen in real life ● Light travels through material ○ 100% of light cannot be preserved ■ Absorption ■ Reflection ● Light not transmitted ● ex) 100% of sunlight reaches the surface of water ○ Of 100% 80% is transmitted ○ 20% reflected ● Same for ophthalmic lens ○ Light passes through lens=> travels to eye => portion of light is reflected ○ It does NOT mean light cancels out ○ It just does not reach the eye Refractive index ● Higher the index, more light would be reflected by front of lens ○ Reduced transmission ○ Acts as mirror Material % reflection CR-39 7.8% Trivex 8.8% Polycarbonate 10,26% High Index 12.32% Ultra-high index 14,58% ● Could be overcomed by lens coating ○ Hard coating ■ Improves resistance on abrasion ■ Varnish on lens ○ Oleophobic coating ■ Replation on oils ■ Maintaining easier ○ Hydrophobic coating ■ Reparation on water and dust ■ Resistance on streak on moisture ● ● ● ● Light transmission of lens impacted by absorption and reflection Increased refraction index=reflects more light=decreased light transmission AR coating = lower reflections = better transmission = better vision Hard coat ○ Damage resistance ● Combination of coating also is possible