Autofocus Modules

High-resolution optical systems, especially microscope lenses, always have a shallow depth of field due to their design. An object must always be within the depth of field of the lens to ensure a sharp figure. When using automated optical inspection systems, the position of the object can change for various reasons (tolerances of the mechanical construction, change in the ambient temperature, etc.) and an automatic adjustment of the focus position becomes necessary.

The integrated autofocus modules in mag.x System 125 enable precise focusing in automated, industrial environments, which is essential for high resolutions. The autofocus solution consists of two subsystems: A first subsystem, the autofocus sensor system, checks the focus position so that a second subsystem, the actuator, can bring the object into the optimal focus position. The method is based on "through-the-lens" laser triangulation. The laser from the autofocus sensor is coupled into the beam path through the base unit to strike the object through the objective lens. The beam reflected by the object passes through the objective lens and the base unit back into the sensor for evaluation of the signal and correction of the focus position.

With mag.x System 125, two actuator solutions are offered: A high-precision piezo unit and a fast motorized Z-axis with a large travel range. Combined with the autofocus sensors from the world's leading manufacturer WiseDeviceInc. this creates a closed-loop system.

The mag.x autofocus solution benefits various applications, including quality control in the production of displays, printed circuit boards, wafers and glass. Because the microscope system supports large area and line sensors, stitching can be eliminated in many cases, allowing for shorter cycle times.