1. Designation of Optical Glass Types

In the course of OHARA's long history, many types of optical glasses have been developed. In this catalogue, you will find 148 glasses that we have selected as our "recommended glass types". Each optical glass has its own properties that are closely connected with the key chemical element contained.

With this in mind, we have developed a new glass type designation system. Our new names are used in this catalogue.

On the - diagram provided in this catalogue, you will see we have divided our glasses into groups. For each glass type, we have selected one or two chemical elements contained which are considered the most important and have used the symbols of these for the first two letters of the glass type designation. The third letter of the glass type designation refers to the refractive index of each glass type within its glass group: H, M or L for high, middle or low. Lastly, we assign a one or two digit number to each glass type within a given glass family. Thus, each glass type is represented by the above mentioned three letters plus a one or two digit number.

We are also adding the prefix "S-" to indicate which of the glass types are ECO optical glasses and are environmentally "Safe". These glass types do not contain any lead or arsenic.

For example, the glass type designation for S-BSL7 is composed as follows:

• S stands for environmentally Safe
• B represents Boron, one of the key compositional elements
• S represents Silicon, one of the key compositional elements
• L indicates a Low index within the BS glass group
• 7 indicates this is the 7th glass within this glass family

Along with OHARA's glass type designation, the technical data sheet will show the six-digit code for each glass type. For your convenience we have included both the / (in bold type) and / codes. These six-digit codes are internationally recognized within the optical community.