Glancing-Angle Laser Positioning for Vacuum Chamber Control
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Solution Overview
Problem
Conventional optical triangulation methods are inadequate for high-resolution position control of objects in high-vacuum or ultra-high-vacuum environments due to the need for large optical windows or separate windows for laser input and output, limiting their application in sensitive analytical techniques.
Innovation Solution
A contactless positioning method using a laser beam incident at a low glancing angle relative to the object's surface, with a screen oriented perpendicular to the displacement direction, allowing for precise detection and control of small displacements without requiring significant separation between the laser source and imaging optics, achieving sub-20 μm resolution at 500 mm working distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If optical triangulation method is used with longer working distance, then measurement range is improved, but spatial separation between laser source and sensitive element must be increased, making the device more complex and requiring larger optical windows for vacuum chamber application
Solution Approach 1:
The patent transitions from conventional optical triangulation (measuring along the beam direction) to a low-glancing-angle method where the laser beam incident angle is reduced to 1-10 degrees relative to the surface. This dimensional change in beam orientation enables high-resolution measurement (sub-20 μm at 500 mm) without requiring large spatial separation between laser source and imaging optics, thus resolving the contradiction between working distance and device complexity
Solution Approach 2:
The patent changes the critical parameter from beam incidence angle (nearly perpendicular in conventional methods) to low glancing angle (1-10 degrees). This parameter change fundamentally alters the measurement geometry, allowing the spot displacement to be highly sensitive to surface position changes while maintaining a compact optical configuration suitable for vacuum chambers with limited window sizes
2Measurement precision
If optical triangulation method is used, then object position can be detected, but large spatial separation between laser source and sensitive element is required, limiting application in vacuum chambers with small windows
Solution Approach 1:
By changing the measurement dimension from along-the-beam direction to lateral displacement at low glancing angle, the patent achieves high position detection precision while minimizing the required optical window area. The low-angle geometry amplifies spot displacement for given surface position changes, enabling precise measurement through small vacuum chamber windows
Solution Approach 2:
The patent separates the measurement function into distinct components: laser beam generation, spot formation on surface, and imaging detection. This segmentation allows optimization of each component independently, enabling precise position detection with compact optical paths that fit within vacuum chamber constraints
3Measurement precision
If conventional optical triangulation is used, then displacement can be measured, but significant separation between laser source and imaging optics is needed, increasing device complexity for vacuum chamber application
Solution Approach 1:
The patent changes the beam incidence parameter from nearly perpendicular to low glancing angle (1-10 degrees), which fundamentally alters the measurement sensitivity. This parameter change enables high displacement measurement precision while maintaining compact optical separation, directly resolving the contradiction between measurement precision and device complexity
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 high-sensitivity detection and control of object displacements with improved resolution, suitable for in-situ analytical techniques, using a single small-size viewport in vacuum chambers, and maintaining spatial stability of electron beams in systems like Low-Angle X-ray Spectrometry.
Implementation Method 1
a laser beam incident at a low glancing angle relative to an object surface
Implementation Method 2
An optical receiver collects the visible light from the spot (indicia) on the surface
Implementation Method 3
An optical receiver collects the visible light from the spot (indicia) on the surface, and converts the collected visible light signals into a spot image onto a linear array of photo-sensitive elements
Data Source
AI summary
A high-sensitivity optical system to determine and/or control spatial displacement and position of objects applicable to various situations when a contact measurement cannot be performed, such as in high-vacuum or ultra-high vacuum chambers, at high temperatures, in aggressive chemical environments, etc. A laser beam is directed at a low glancing angle to a screen secured to an object. The screen's surface is normal to a motion direction of interest. A location of the bright laser beam spot on the screen surface is acquired and the displacement thereof is analyzed and quantified based on the change in distance from the laser beam spot to a reference element which is arranged on the screen and creates a variation in the acquired image brightness. A feedback loop control mechanism is provided which returns the displaced object to its original position.