Focusing an optronic device generally presents a set of challenges based on the desired resolution and operating conditions. Focusing an optronic device, IN FLIGHT, presents a completely different set of challenges. The process of moving a lens to a precise location and holding position, while subjected to shock/vibration, temperature variations and changing orientation dictates the use of a direct drive motor with a very high natural frequency and fast response time.
As flight applications restrict the size and weight of a device, motion modules with traditional motors and drive screws suffer from compromised performance and limited life. The ability to configure small modules with a direct drive piezo motor offers the ability to optimize size, weight and power, yielding performance and operational life well beyond conventional technology.
When you consider moving 20mm distance with a mass in the range of 25 to 30grams, operating in random orientations from vertical to horizontal, exposed to high shock and vibration, it is essential to design an axis with a very high natural frequency and high stiffness in the moving axis.
An auto focus module, with 0.25µm resolution, positioning to 2.5µm under vibration of more than 12 G, fits into a volume of ~45mm x ~60mm with a total assembly weight less than 50grams. This configuration is capable of performing the required focusing with the most challenging operating conditions.