Faster, advanced center thickness measurement for optics manufacturing

In 2022, TRIOPTICS introduced two innovations to the OptiSurf^® center thickness measurement system: a reduction in measurement time by a factor of 3 and the new LensGage accessory module, which allows center thickness determination without knowledge of the material’s refractive index.

TRIOPTICS introduced the new version of the OptiSurf^® center thickness measurement system at Photonics West 2022. This received a comprehensive upgrade for all variants operating with a test wavelength of 1.3 µm to optimize data acquisition as well as the communication interface. “Users notice this improvement in the measurement speed, which is now 3x as fast as before,” explains Division Manager Dr. Patrik Langehanenberg. “This means that our OptiSurf^® now offers the fastest center thickness measurement on the market for complex lens systems with optical path lengths greater than 50 mm.”

At the same time, all OptiSurf^® versions received a new software. It now enables more intuitive operation and a future-proof programming environment for customer-specific applications.

A significant extension of the application possibilities arises especially for the OptiSurf^® LTM through the introduction of the new accessory module LensGage. “It allows the measurement of the center thickness without knowledge about the material with a measuring accuracy of 1.5 µm. Furthermore, it determines the group refractive index of individual lenses with a precision of ~10-4 for production control – e.g. in critical manufacturing processes such as for molded lenses,” Langehanenberg reports. With this information, it is additionally possible to determine or at least narrow down the material by comparing it with the glass database stored in the software.

The LensGage module consists of two glass plates, one above and one below the sample, which complement the existing sample holder. The glass plates form the boundary of the measuring cell, which is used to calculate the center thickness and the group refractive index, respectively. This procedure is also embedded in the software, so that the value sought can be read directly. Switching between LensGage and classical measurement is easily possible by removing the lower glass plate. The high thermal stability of the module through the use of Invar ensures reproducible measurement results and low calibration effort.