Optical Position Measuring Device 3D Displacement Detection
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Solution Overview
Problem
Existing optical position-measuring devices can only simultaneously detect two degrees of freedom, such as vertical and lateral displacement, between movable objects, and are not suitable for measuring tasks requiring more than two degrees of freedom.
Innovation Solution
An optical position-measuring device that uses a scanning unit connected to one object and a reflection scale connected to another, employing multiple pairs of partial beams split and deflected through splitting elements and detectors to detect displacement-dependent signals for three spatial degrees of freedom, including vertical and two lateral displacements, with the aid of two-dimensional diffraction structures and structured photodetectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an optical position measuring device uses a scanning unit with splitting elements to detect multiple degrees of freedom, then the measurement capability increases from two to three degrees of freedom, but the device complexity increases due to additional splitting elements, deflection elements, and detectors
Solution Approach 1:
The patent extends the measurement capability from two to three degrees of freedom by adding a third splitting plane perpendicular to the first two splitting planes. This dimensional extension allows the device to measure vertical and two lateral displacement directions simultaneously, transforming a 2D measurement system into a 3D measurement system through the addition of orthogonal splitting planes and associated optical components.
2Measurement precision
If the device uses multiple pairs of partial beams for three degrees of freedom measurement, then position determination precision improves, but the quantity of optical components and detectors increases
Solution Approach 1:
The patent divides the optical measurement function into multiple independent partial beam pairs, each responsible for measuring specific displacement components. The incident beam is segmented into multiple partial beams through successive splitting in three perpendicular planes, with each pair of partial beams interfering to provide information about a specific degree of freedom, thereby distributing the measurement function across multiple specialized optical paths.
Solution Approach 2:
The patent employs three mutually perpendicular splitting planes to create a three-dimensional measurement capability. Each splitting plane generates partial beams that interfere to measure displacement in a specific direction, with the three planes working orthogonally to provide complete 3D position determination, thereby extending the measurement space from two to three dimensions.
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 spatial determination of the position of two movable objects in at least three spatial degrees of freedom, allowing for high-resolution position determination and reduction of undesired interference beams, thereby improving measurement accuracy.
Implementation Method 1
a beam of rays incident from a light source undergoes splitting in the scanning unit via a first splitting element into at least a first, second and third partial beam of rays in a first splitting plane
Implementation Method 2
the second partial beam of rays is split by a second splitting element into at least a fourth and fifth partial beam of rays
Implementation Method 3
Relative position information results from the interfering superimposition of at least two pairs of partial beams of rays
Implementation Method 4
The first and third partial beams of rays are then deflected in the direction of the reflection scale graduation via deflection elements in the scanning unit
Data Source
Figure 1a~1b
Figure 2
Figure 3a~3b
AI summary
The present invention relates to an optical position measuring device for detecting the relative position of two objects moving relative to each other. Relative position information results from the interfering superposition of at least two pairs of partial beams. A beam incident from a light source is split in a scanning unit by a first splitting element into several partial beams in a first splitting plane. A portion of the partial beams passes through deflecting elements towards a reflection standard, while another partial beam is split into further partial beams by a second splitting element. At least two pairs of partial beams interfere at two points of impact on the reflection standard.First and second detectors capture displacement-dependent first and second scanning signals, from which position information regarding the vertical and first lateral displacement directions of the objects can be derived. In the scanning unit, the incident beam is further split by the first splitting element into additional partial beams in a second splitting plane oriented perpendicular to the first. These partial beams propagate in the second splitting plane analogously to the partial beams in the first splitting plane. Third and fourth detectors capture displacement-dependent third and fourth scanning signals, from which position information regarding the vertical displacement direction and a second lateral displacement direction of the objects can be derived (Fig. 1a).