Mirror Actuator Segmentation for Eigen Frequency Control
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Solution Overview
Problem
Existing optical apparatuses face challenges in accurately correcting optical aberration due to mirror vibration and low eigen frequency, primarily because they use actuators with low rigidity to deform the mirror's reflecting surface, making it difficult to support the mirror effectively.
Innovation Solution
The optical apparatus employs a combination of high-rigidity first actuators connected directly to the mirror's rear surface and low-rigidity second actuators between the mirror and base plate, along with sensors and a control unit to adjust the mirror's shape, using a coupling mechanism to absorb length errors and minimize deformation during assembly, and a compliance matrix to control the actuators for precise deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If low-rigidity actuators are used to deform the mirror surface, then the mirror can be supported at peripheral portions, but the eigen frequency of the mirror becomes low causing vibration
Solution Approach 1:
The support system is segmented into two distinct actuator types: first actuators with high rigidity for primary support and frequency stabilization, and second actuators with low rigidity for fine deformation control. This segmentation allows each actuator type to perform its specialized function without compromising the other.
Solution Approach 2:
Different regions of the mirror support structure are assigned different actuator types with different rigidity characteristics. The first actuators provide high-rigidity support at critical locations to maximize eigen frequency, while second actuators provide low-rigidity control at other locations for deformation capability.
2Stability of the object's composition
If high-rigidity actuators are used to increase mirror eigen frequency, then mirror vibration is reduced, but the ability to deform the reflecting surface accurately is compromised
Solution Approach 1:
The deformation control function is segmented between two actuator systems: first actuators with high rigidity maintain structural stability and eigen frequency, while second actuators with low rigidity provide the compliance needed for precise surface deformation control.
Solution Approach 2:
The second actuators act as intermediaries between the high-rigidity first actuators and the mirror surface, providing the necessary compliance for precise deformation while the first actuators maintain the overall structural integrity and frequency characteristics.
3Manufacturing precision
If multiple actuators are used to control mirror deformation, then surface shape control is improved, but assembly length errors and deformations occur
Solution Approach 1:
A coupling mechanism with absorption capability is installed beforehand to compensate for and cushion the effects of length errors in the actuators, preventing these errors from causing assembly deformations or affecting the final mirror surface accuracy.
4Manufacturing precision
If actuators are controlled to deform the mirror, then optical aberration correction is achieved, but mirror vibration occurs during deformation
Solution Approach 1:
The control system is segmented into two independent control loops: one controlling the high-rigidity first actuators to maintain eigen frequency and minimize vibration, and another controlling the low-rigidity second actuators to achieve the desired surface deformation for aberration correction.
Solution Approach 2:
The system changes the rigidity parameter of the support structure by using two types of actuators with different rigidity values, allowing the mirror to be supported with high rigidity for frequency stability while enabling controlled deformation through the low-rigidity actuators.
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
This configuration allows for accurate and high-speed deformation of the mirror's reflecting surface, increasing the eigen frequency and reducing vibrations, thereby enabling precise correction of optical aberration.
Implementation Method 1
Each of the plurality of first actuators 2 has a first terminal 2a connected to a surface opposite to the reflecting surface of the mirror 1 and a second terminal 2b connected to the base plate 6, and applies a force to the surface opposite to the reflecting surface by deforming so as to change a distance between the first terminal and the second terminal
Implementation Method 2
a sensor configured to detect information indicating a driving status of each of the plurality of first actuators
Data Source
AI summary
The present invention provides an optical apparatus for deforming a reflecting surface of a mirror, comprising a base plate, a plurality of first actuators each configured to apply a force to the surface opposite to the reflecting surface, a plurality of second actuators each having rigidity lower than that of the first actuator, and configured to apply a force to the surface opposite to the reflecting surface, a sensor configured to detect information indicating a driving status of each of the plurality of first actuators, and a control unit configured to control, based on an output of the sensor, driving of each of the plurality of first actuators and driving of each of the plurality of second actuators so that a shape of the reflecting surface is changed to a target shape.