Optical Stage Alignment Using Scale Feedback for Thermal Drift
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Solution Overview
Problem
Current optical apparatuses face challenges in accurately directing optical instruments to desired positions on moving objects due to thermal expansion, contraction, and deformation, which can result in significant displacement, especially in applications requiring precision like laser processing where tolerances need to be within 1 μm or less.
Innovation Solution
An optical apparatus with a stage device and detection mechanism that includes scales and detection heads to measure deviations in X-axis and Y-axis directions, coupled with a control device to adjust the optical instrument's position, ensuring accurate alignment by displacing the optical axis and correcting for any displacement between the target and actual positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control is applied to the stage position, then the stage can be controlled to move to target positions, but displacement occurs between target position and actual position due to thermal expansion and deformation
Solution Approach 1:
The patent implements a feedback control mechanism where the detection head continuously reads the scale position and compares it with the target position. The control device adjusts the stage movement based on the detected deviation, creating a closed-loop system that compensates for thermal expansion and deformation effects in real-time, thereby maintaining position accuracy stability.
Solution Approach 2:
The patent replaces traditional mechanical position measurement methods with an optical measurement system. The scale and detection head form an optical measurement mechanism that reads position information optically, which is less affected by thermal expansion of mechanical components, thereby improving measurement precision and reliability.
2Adaptability or versatility
If the object is moved by the XY stage to direct the optical instrument, then the optical instrument can be directed to any portion of the object surface, but slight displacement occurs in laser irradiation position due to thermal changes
Solution Approach 1:
The detection head continuously monitors the actual position of the object surface under the optical instrument and feeds this information back to the control device. The control device compares the actual position with the target position and adjusts the XY stage movement accordingly, ensuring that laser irradiation position accuracy is maintained despite thermal changes during processing.
Solution Approach 2:
The scale creates a reference position framework that is read by the detection head. This reference framework serves as a stable positional copy that is not affected by thermal expansion of the XY stage mechanical structure, allowing accurate position tracking and compensation.
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 precise and accurate direction of optical instruments to the desired target position on moving objects, maintaining the required precision even with thermal changes, thus enhancing the accuracy of processes like laser processing.
Implementation Method 1
a detection head provided on the table and configured to read a position on the scale
Data Source
AI summary
In order to implement a stage device for an optical instrument capable of accurately directing the optical instrument to a desired target position on an object supported by a moving stage, a stage device 2 for an optical instrument includes a table 22 configured to support an object and to move together with the object to cause an optical instrument 1 to be directed to any portion of the object; and a detection mechanism configured to detect a deviation between a target position to which the optical instrument 1 is to be directed on the object supported by the table 22 and a position to which the optical instrument 1 is actually directed.