Retroreflector Calibration Scale for Vision Measuring Machines
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Solution Overview
Problem
Vision measuring machines with coordinate measuring systems face challenges in obtaining uniformly bright image data during oblique inspections, especially with transmission illumination units, leading to difficulties in calculating accurate distances and errors due to varying light distances and insufficient brightness with vertical illumination units.
Innovation Solution
A vision-measuring-machine calibration scale with a light-transmissive region and light-shielding region on its surface, equipped with a retroreflector on the rear surface that retroreflects transmitted light, ensuring uniform brightness and clear image data capture, and allowing for detachable installation to accommodate different illumination setups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transmission illumination unit is used to illuminate the calibration scale, then the light can pass through the light-transmissive scale board, but the brightness becomes non-uniform due to varying distances between the horizontally moved light source and the calibration scale
Solution Approach 1:
A retroreflector is introduced as an intermediary element between the light source and the calibration scale. The retroreflector receives light from the light source and redirects it back through the scale board, ensuring that the light path length remains constant regardless of horizontal movements. This mediator resolves the brightness uniformity issue while preserving illumination setup flexibility.
Solution Approach 2:
The solution transitions from horizontal illumination (parallel to the scale board) to vertical illumination (perpendicular to the scale board) by introducing the retroreflector. This dimensional change in light direction ensures that the distance between the light source and scale board remains constant, achieving uniform brightness while maintaining versatility.
2Illumination intensity
If a vertical illumination unit is used to illuminate the calibration scale, then the distance between the light source and scale board remains constant, but the brightness is insufficient because the metal thin layers do not reflect enough light back to the objective lens
Solution Approach 1:
The retroreflector serves as a mediator that enhances the light reflection from metal thin layers. By positioning the retroreflector behind the scale board, it captures light that passes through the scale board and reflects it back through the metal thin layers, significantly increasing the brightness returned to the objective lens while maintaining constant distance geometry.
3Illumination intensity
If the calibration scale is made transparent to allow light transmission, then light can pass through for illumination, but the metal thin layers block light creating dark portions in the captured image data
Solution Approach 1:
The retroreflector acts as an intermediary that compensates for the light blocking effect of metal thin layers. Light that would otherwise be blocked by the metal layers passes through the transparent scale board, interacts with the retroreflector, and is reflected back through the metal layers, ensuring that the objective lens receives sufficient light to capture complete image data without dark portions.
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
The solution provides uniformly bright image data, enabling clear reading of coordinates and accurate error calculation in vision measuring machines, even with varying illumination setups, and allows for flexible use in different inspection configurations.
Implementation Method 1
a retroreflector that is provided on a rear surface of the scale body and that retroreflects transmitted light irradiated from the side of the front surface of the scale body and transmitted through the scale body
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
A vision-measuring-machine calibration scale (1) including: a scale body (10) having a light-transmissive region (10A) and a light-shielding region (10B) arranged on a front surface of the scale body (10) in a predetermined pattern; and a retroreflector (11) provided on the side of a rear surface of the scale body (10) and retroreflecting transmitted light irradiated from the side of the front surface of the scale body (10) and transmitted through the scale body (10).