Improving Surgical Techniques. Variable Focusing and Optimal Sharpness for Endoscopic Applications

Modern medical technology focuses on developing therapies that cause as little discomfort to patients as possible. Endoscopes that allow minimally invasive surgery, make an important contribution to this, for example, in laparoscopy. Especially during medical interventions, the demand for focused and detailed image information is of the highest priority in order to achieve the best possible chances of success.

In chip-on-the-tip endoscopes, the image information is transmitted via an image sensor in the tip of the endoscope. However, previous chip-on-the-tip endoscopes use fixed-focus optics that can only display one object gap properly. If the object is at a different distance, the image loses focus. By integrating a miniature drive, it could become possible to achieve variable focusing, so that the object can always be displayed optimally in sharp focus. However, with diameters of no more than 10 mm, the potential installation space is very small. Nevertheless, it is not impossible to find suitable drives for the zoom and focus lens.

As a specialist for precision drives, PI offers several solutions for this challenge.

For example, piezo ultrasound drives offer interesting approaches. The functional principle of these direct drives is always the same: Piezoceramic actuator oscillation at ultrasonic frequencies are converted into linear motion along a runner and drives the moving part of a mechanical structure that the lens is then attached to.

These lightweight drives supply smooth motion with theoretically unlimited range, travel speeds up to approximately 100 mm/s and an open-loop motion resolution of approximately 100 nm.

Thanks to their small dimensions and their favorable cost/performance ratio, piezo-based inertia drives are likewise ideally suitable for use with endoscopes. They use the stick-slip effect for achieving unlimited travel ranges and have a resolution of a few nanometers.

In addition to piezo-based drives, miniaturized linear direct drives, e.g. the voice coil drives of the PIMag^® series, offer good conditions for use in modern video endoscopes. The extremely small designs and the travel ranges of a few millimeters to centimeters required in endoscopes can be realized very well with this technology.