Lens Positioning Assembly Using Voice Coil Actuation
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Solution Overview
Problem
Existing microscope objective lens positioning systems face challenges in achieving rapid and large movements due to the weight of the lens and support assembly, limiting refocusing speed and accuracy, especially when using piezoelectric elements that can only move small distances at low accelerations.
Innovation Solution
A lens positioning assembly with a movably connected lens mounting member, an actuator applying force along the optical axis, and a reflector to redirect radiation, combined with a flexure mechanism and stiffening members to maintain alignment and reduce resonance, allowing for greater movement distances and higher accelerations while minimizing image distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a piezoelectric element is used to move the microscope objective lens, then the lens can be moved with good precision, but the movement distance is limited to less than 500 microns and acceleration is low
Solution Approach 1:
A voice coil actuator serves as an intermediary device between the control system and the lens mounting member. The voice coil generates electromagnetic force to move the lens assembly, replacing the piezoelectric element. This intermediary approach enables larger movement distances (up to 6 mm) and higher accelerations (27 m/s²) while maintaining positioning precision through controlled electromagnetic actuation.
Solution Approach 2:
The patent replaces the mechanical piezoelectric actuation system with an electromagnetic voice coil actuation system. This substitution allows for greater force application and larger displacement ranges while maintaining precise control over the lens positioning, resolving the contradiction between precision and speed.
2Reliability
If the lens and support assembly are made heavy for stability, then imaging quality is maintained, but rapid movement becomes difficult to achieve
Solution Approach 1:
The voice coil actuator provides a counteracting electromagnetic force that overcomes the gravitational and inertial forces of the heavy lens assembly (over 100 grams). By applying sufficient electromagnetic force, the system achieves high accelerations (27 m/s²) despite the heavy mass, enabling rapid refocusing while maintaining imaging stability through controlled motion.
3Measurement precision
If the reflector is mounted independently of the lens mounting member, then a fixed path to the detector is maintained, but the system complexity increases
Solution Approach 1:
The reflector is extracted from the moving lens mounting assembly and mounted independently on the stationary support structure. This separation ensures that the optical reflection path remains fixed and stable during lens movement, maintaining measurement precision. The independent mounting, while adding some structural elements, simplifies the overall system by decoupling the reflection function from the movement mechanism.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables high-acceleration movement of heavy lenses with minimal impact on imaging time, maintaining precise alignment and reducing resonance-induced vibrations, suitable for various lenses including microscope objective lenses.
Implementation Method 1
an actuator on the optical axis of the lens for applying a force to the lens mounting assembly the force passing through the centre of mass of the lens
Implementation Method 2
a reflector mounted independently of the lens mounting member for reflecting radiation passing through the objective lens away from the optical axis
Implementation Method 3
a flexure connecting the lens mounting assembly to the support member to enable the lens mounting assembly to move relative to the support member
Data Source
AI summary
A microscope objective lens positioning assembly comprises a lens mounting member to which a microscope objective lens defining an optical axis is mounted; a support member; and a pair of leaf springs. Each leaf spring has first and second ends, the first ends of the leaf springs being secured to upper and lower aligned locations respectively on the support member, and the second ends of the leaf springs being secured to corresponding upper and lower locations respectively on the lens mounting member whereby the two leaf springs, the optical axis of the objective lens, and a line between the upper and lower aligned locations on the support member define a parallelogram, the leaf springs flexing in use in response to movement of the lens mounting member.