Anti-shock and vibration lenses can be used in robotics
Following research into the robustness of lenses, Fujinon has developed a dedicated anti-shock and vibration design. The HF-12M and HF-5M series are available through vision specialist Framos.
The design has been tested under 10G and sine wave vibration at up to 500Hz and 100m/s². It is particularly suitable for applications in robotics and in high-vibration environments, such as industrial imaging systems dealing with motion, shock, or vibration which benefit from consistent image quality and less maintenance, says Framos.
Most machine-vision installations use cameras with C-mount lenses with fixed focal lengths, which need to provide consistent image quality even irrespective of harsh conditions. Modern robotic arms are so powerful that they can move loads with several multiples of the acceleration due to gravity (unit G, 1 G = 9.81 m/s²). Robot-guided image processing systems must withstand these accelerations and are additionally exposed to the vibrations at the tip of the robot arms. The same applies to camera-lens setups on large machines with rotating elements.
Industrial vision systems are often exposed to severe mechanical stress and environmental factors. Bumping and vibration can cause a significant decrease in resolution and a shift in the optical axis. For customers with robotic applications, mobile systems or even fixed solutions in harsh environments, a rugged and durable lens design is essential to ensure high image and analysis quality, says Framos.
In the Fujinon test set-up, the lenses are tested for their robustness against shocks and vibrations, and are repeatedly exposed to shocks of up to 10 G and from six directions perpendicular to the optical axis. Subsequently, sinusoidal vibrations according to IEC 60068-2-6 with up to 500Hz and 100m/s² are added. As a result, the optical axis of a conventional lens shifts by up to 26-micron, which is equivalent to about seven pixels for second-generation Sony Pregius sensors. Measured by contrast charts, the resolution decreases dramatically, making the lenses useless, reports Framos. For developers of mechanically stressed imaging systems robustness against shocks and vibrations are equally important as the optical format, the resolution and the focal length of lenses.
Fujinon’s anti-shock & vibration design is based on a patented elastic fixation of the internal lens arrangement, which provides long-term protection against shocks and vibrations, but also works well with changes in humidity and temperature. The optical axis shifts only by four to a maximum of 10-microns, dependency on adhesives is minimised and a long-term stable performance and consistently good image quality is guaranteed.