American Board of Opticianry (ABO) Practice Test

What process involves the chemical tempering of a glass lens?

1. UV-Curing

2. Thermal Hardening

3. Chemical Coating

4. Ion Exchange

The correct answer is: Ion Exchange

The correct answer is Ion Exchange. This process involves immersing the glass lens in a bath of molten salt and then cooling it rapidly. The salt ions replace the smaller glass ions, creating a compressive layer on the surface of the lens which increases its strength and durability. Option A, UV-Curing, involves using ultraviolet light to harden a special resin coated on the glass lens. This process does not involve any chemicals. Option B, Thermal Hardening, is a similar process where the glass lens is heated and then rapidly cooled to create a hardened layer, but it does not involve any chemical tempering. Option C, Chemical Coating, also involves a chemical process but it is not the same as ion exchange. In this process, a thin layer of chemicals is applied to the glass lens to improve its optical properties or provide additional features such as anti-reflective or scratch-resistant coating. Overall, Ion Exchange is the correct answer for this question as it specifically refers to the process of chemically tempering glass lenses to increase their strength and durability.