Optical Scanner Astigmatism Compensation via Inclined Plate
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Solution Overview
Problem
Existing optical scanners using MEMS devices for light deflection often suffer from astigmatism, causing the beam spot diameter to spread and resulting in undesirable scanning light quality.
Innovation Solution
The optical scanner incorporates a light deflector with a reflection plane that is moved biaxially by piezoelectric drive circuits, and a planar light transmission member, such as a light-intensity adjustable member, is inclined to reduce astigmatic differences by adjusting the optical paths of laser beams in the main and sub-scanning directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a MEMS light deflector is used to perform optical scanning, then the scanning speed and resolution are improved, but astigmatism occurs causing the beam spot diameter to spread
Solution Approach 1:
A planar light transmission member (optical plate) is introduced as an intermediary component between the light source and the light deflector. This optical plate compensates for astigmatism by adjusting the optical path, thereby maintaining beam focus while preserving the high scanning performance of the MEMS device.
Solution Approach 2:
The optical plate is designed with specific parameter configurations including inclination angle relative to the optical axis, and controlled curvature in directions orthogonal to the torsion bar axis. By adjusting these parameters, the system compensates for astigmatism induced by the MEMS deflector's rotation.
2Adaptability or versatility
If the reflection mirror is rotated biaxially for two-dimensional scanning, then the scanning coverage is improved, but astigmatic aberration increases
Solution Approach 1:
The planar light transmission member serves as a compensating intermediary that counteracts the astigmatic effects produced by biaxial rotation of the reflection mirror, enabling maintained beam quality across the full two-dimensional scanning range.
Solution Approach 2:
The optical plate is designed with asymmetric curvature characteristics - having curvature in directions orthogonal to the torsion bar axis but not necessarily in other directions. This asymmetric design specifically targets and compensates for the astigmatism pattern generated by the biaxial scanning 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
This configuration effectively reduces astigmatism, maintaining a consistent focal point and improving the quality of the projected image by compensating for curvature-induced astigmatic differences, thereby enhancing the scanning light's focus and reducing random noise.
Implementation Method 1
a reflection plane 14 provided for a light deflector 13 is moved biaxially in accordance with a driving signal input from a control device 11
Implementation Method 2
an optical scanner that deflects the light emitted from a light source to perform optical scanning on a target scanning area
Data Source
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AI summary
An optical scanner (10), an image projection apparatus, a mobile object, and a method of manufacturing the optical scanner. The optical scanner (10) includes a light source (12) configured to emit light, a light deflector (13) configured to deflect the light emitted from the light source (12), and a planar light transmission member (61, 513) disposed in an optical path between the light source (12) and the light deflector (13). In the optical scanner (10), the planar light transmission member (61, 513) is inclined with reference to an optical-axis direction of the optical path to reduce an astigmatic difference (ΔF) caused to the light deflected by the light deflector (13) due to astigmatism. The image projection apparatus (500) includes the optical scanner (10) and a projection optical system (511) configured to project light emitted from the optical scanner (10) to a target scanning area (15). In the image projection apparatus (500), the light deflector (13) of the optical scanner (10) scans the target scanning area (15), using light modulated based on image data, to project an image. The mobile object (400, 701) includes at least one of the optical scanner (10) and the image projection apparatus (500).