Rotating Mirror Compensates Front Pane Astigmatism
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Solution Overview
Problem
Conventional laser scanners face challenges in accurately detecting objects due to the beam-shaping influences of curved front panes, which result in astigmatic effects that cannot be corrected by stationary optical elements, leading to reduced measurement accuracy and increased extraneous light, especially in miniaturized designs.
Innovation Solution
A rotating mirror with a curved mirror surface is used as a movable optical element to compensate for the beam-shaping effects of the front pane, ensuring that the optical system remains invariant and effectively corrects astigmatic influences, thereby improving imaging properties and reducing the light spot size on the receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a curved front pane is used in miniaturized laser scanners, then the compact size is achieved, but the beam-shaping effects cause astigmatic distortion and reduced measurement accuracy
Solution Approach 1:
The patent applies the dynamics principle by making the optical element (mirror or lens) movable relative to the front pane. The optical element is positioned at a variable distance from the front pane during operation, allowing the system to dynamically adjust and compensate for the astigmatic distortion caused by the curved front pane in miniaturized configurations.
2Volume of moving object
If a curved front pane is used, then the compact design is enabled, but extraneous light increases and signal-to-noise ratio decreases
Solution Approach 1:
The movable optical element allows dynamic adjustment of the optical path, enabling the system to compensate for beam-shaping effects that cause extraneous light to enter the receiver. By varying the distance between the optical element and the front pane, the system can minimize the impact of scattered and reflected light.
3Device complexity
If stationary optical elements are used to correct beam-shaping effects, then the system structure is simplified, but correction of astigmatic effects is insufficient
Solution Approach 1:
The patent explicitly moves away from stationary optical elements to a dynamic configuration where the optical element can vary its distance from the front pane. This dynamic capability enables effective correction of astigmatic distortion that stationary elements cannot achieve in miniaturized scanners with curved front panes.
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 solution enhances measurement accuracy and range by minimizing extraneous light and increasing the signal-to-noise ratio, allowing for more precise object detection and improved detection properties in laser scanners.
Implementation Method 1
A light beam generated by a laser is periodically scanned across a monitoring area by means of a deflection unit. The light is reflected from objects within the monitoring area and evaluated in the scanner.
Implementation Method 2
The transmitted light and reflected transmitted light exit the sensor through a surrounding front lens into the monitoring area and back into the sensor, respectively. The area through which the scan beam passes through the front lens is not flat, but curved, and therefore inevitably influences the path of the beam.
Data Source
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AI summary
An optoelectronic sensor 10 for detecting objects in a monitoring area 20 is described, wherein the sensor 10 comprises a light transmitter 12 for emitting transmitted light 16, a movable deflection unit 18 for periodically deflecting the transmitted light 16, a light receiver 26 for generating a received signal from transmitted light 22 reflected by objects in the monitoring area 20, a control and evaluation unit 32 for acquiring information about objects in the monitoring area 20 based on the received signal, and a rotating front panel 38 with a passage area 40 for the transmitted light 16 and/or the reflected transmitted light 22. An optical element moving with the deflection unit 18 is provided, which compensates for any refractive influence of the front panel 38 on transmitted transmitted light 16 and/or reflected transmitted light 22.The deflection unit 18 is preferably designed as a rotating mirror, the mirror surface of which preferably has a curvature and thus functions as the moving optical element. In other words, the rotating mirror itself is the moving optical element. The mirror surface is preferably designed as a freeform shape. The invention is based on the fundamental idea of compensating for beam-shaping influences of the front glass 38 on the transmitted or reflected transmitted light. Due to the curvature of the front glass 38 in the transmission area 40, the individual rays of the beam formed by the transmitted or reflected transmitted light experience different deflections. The invention has the advantage that the imaging properties in the sensor 10 are improved. Since the interfering influences of the front glass 38 are compensated for, a significantly smaller received light spot can be generated on the light receiver 26.This allows the useful light to be captured as completely as possible on a small receiving area with minimal extraneous light, thereby increasing the signal-to-noise ratio and consequently the measurement accuracy and range.