Quick and accurate measurement of effective focal length and flange focal length
In addition to effective focal length, flange focal length is particularly important when manufacturing camera lenses. This determines the distance to the camera sensor, thereby influencing the quality of the lens. With the OptiSpheric® AF 500 INV, TRIOPTICS has developed a measurement instrument with which these parameters can be quickly and reproducibly measured – regardless of their physical length. Mounting lenses on the measurement instrument is additionally facilitated by the simple implementation of customer-specific sample receptacles. In addition to determining effective focal length and flange focal length, the OptiSpheric® AF 500 INV can also measure back focal length, radius and MTF for camera lenses with a length of up to 300 mm.
The system is based on the established OptiSpheric® product series. In contrast to that system, however, the structure has been reversed. "This allows numerous improvements and simplifies the measurement of flange focal length of lenses," explains product manager and developer Dr. Judith Krawinkel. "We can use both self-centering holders for testing single components and customized mounts, such as camera-specific bayonet connections. Lenses are mounted securely and significantly more stably on the measurement system as a result. At the same time, fine adjustments of the lens position are still possible." Stability is additionally increased by a vibration-damped granite table, which provides for independence from the environment.
The measurement system was designed as a compact Setup without external moving parts. Together with its tried-and-tested software, it is simple and user-friendly to operate. As a result, the system is also suitable for use in production. The integration of a precise stage and an optional linear encoder result in significantly higher reproducibility of the measurements.
As with all OptiSpheric® models, the OptiSpheric® AF 500 INV can be equipped with a filter and motorized reticle changer. This enables measurements at different wavelengths and the automation of the measurement process.