Hardness Testing Method Using Dual Field Lenses
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Solution Overview
Problem
Conventional hardness testers face challenges in accurately positioning specimens during indentation testing, leading to measurement errors due to deep field depth with low power lenses and increased testing time with high power lenses, which require capturing numerous images to obtain a broad range image.
Innovation Solution
A hardness testing method that uses a combination of high and low power field lenses to focus and capture images, allowing for pre-indentation measurement of focus positions and storage of this information for precise specimen positioning, thereby reducing the need for extensive autofocus processes and minimizing measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a low power field lens is used to capture a broad range image, then the field of view is increased, but the field depth becomes excessively deep causing measurement errors during indentation scanning
Solution Approach 1:
The patent performs preliminary autofocus at the test position before indentation is created. The focus position is determined in advance when the test position is set, and this pre-determined focus position is then used during the indentation scanning process. This preliminary action ensures that the specimen is properly focused before the actual hardness test, preventing measurement errors that would otherwise occur when using low power lenses with deep field depth.
2Measurement precision
If a high power field lens is used to obtain precise focus, then measurement precision is improved, but the field of view becomes narrow requiring capture of numerous images to obtain a broad range image
Solution Approach 1:
The patent performs preliminary autofocus at the test position before indentation is created. The focus position is determined in advance when the test position is set, and this pre-determined focus position is then used during the indentation scanning process. This eliminates the need to capture numerous images with high power lenses during the actual testing, as the focus position has already been established beforehand.
Solution Approach 2:
The patent separates the broad range image capture function from the precise measurement function. Low power lenses are used for capturing the broad range image to establish test positions, while high power lenses are used only for the critical autofocus and measurement steps. This segmentation allows each lens type to be used for its optimal purpose, reducing the total number of images that need to be captured and processed.
3Measurement precision
If autofocus process is performed during indentation scanning, then focus accuracy is maintained, but the execution time of hardness tests is increased
Solution Approach 1:
The patent performs preliminary autofocus at the test position before indentation is created. The focus position is determined in advance when the test position is set, and this pre-determined focus position is then used during the indentation scanning process. By performing the autofocus action beforehand, the patent eliminates the need for time-consuming autofocus operations during the actual indentation scanning, thereby maintaining focus accuracy while significantly reducing testing time.
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 approach enables accurate and efficient specimen positioning, shortening the execution time of hardness tests while preventing measurement errors, and allows for the use of low power lenses to capture broad range images without needing multiple images, thus reducing overall testing time.
Implementation Method 1
a focusing process of positioning a first field lens (15a) above the specimen S and focusing on a surface of the specimen S by changing a relative distance between the specimen stage (2) and the first field lens (15a)
Implementation Method 2
a first image capturing process of positioning a second field lens (15b) having a magnification power less than the first field lens (15a) above the specimen S and capturing an image of the surface of the specimen S with an image capturer (12)
Data Source
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AI summary
A hardness tester 100 and a hardness testing method including a focuser 4, 5, an image capturer 12, a test position setter 61, a focus position memory 61, an indentation creator 61, an image capture controller 61, and a measurer 61. The focuser 4, 5 focuses on the surface of the specimen S. The image capturer 12 captures an image of the surface of the specimen S through one of a first field lens 15a and a second field lens 15b. The test position setter 61 sets a test position at which the indentation is formed based on image information captured through the second field lens 15b. The focus position memory 61 measures a focus position through the first field lens 15a at a predetermined test position among the set test positions, then associates the focus position with a test position within a predetermined range and stores the information in a memory 63. The indentation creator 61 forms the indentation at the test position with the indenter 14a. The image capture controller 61 displaces the specimen S based on the test position and the focus position, then captures an image of the formed indentation through the first field lens 15a. The measurer 61 measures the hardness of the specimen S based on the indentation whose image has been captured.