Spatial Light Modulator Multi-Target Laser Measurement
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Solution Overview
Problem
Conventional laser tracking methods for measuring distance are limited by their ability to monitor only a single reflector at a time, are labor-intensive, prone to mechanical errors, and suffer from reduced accuracy due to angle-based measurements, especially at larger distances.
Innovation Solution
A measurement system utilizing a spatial light modulator to split a measurement beam into multiple components, allowing simultaneous illumination and measurement of multiple targets with increased signal intensity and accuracy, using frequency scanning interferometry for distance determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a laser tracker steers to monitor multiple reflectors sequentially, then all targets can be measured, but the measurement process becomes time-consuming and labor-intensive
Solution Approach 1:
The patent divides a single measurement beam into multiple separate beams using a beam splitting element, allowing each beam to independently illuminate and measure different reflectors simultaneously. This segmentation of the beam enables parallel measurement of multiple targets, eliminating the sequential steering process and significantly reducing measurement time while maintaining complete target coverage.
Solution Approach 2:
The patent combines multiple measurement functions into a single instrument by integrating a beam splitting element within the laser tracker. This merging allows the device to perform simultaneous multi-target measurement that would otherwise require multiple sequential operations, resolving the contradiction between measurement completeness and time efficiency.
2Measurement precision
If the laser tracker uses angle-based measurements to determine target position, then three-dimensional coordinates can be obtained, but uncertainty increases at large distances due to thermal gradients and air turbulence
Solution Approach 1:
The patent replaces the angle-based measurement mechanism with a range-based measurement system using frequency scanning interferometry. This substitution eliminates the angle sensors and beam steering mechanisms that are susceptible to thermal gradients and air turbulence, thereby improving measurement stability and reliability in industrial environments while maintaining the ability to determine three-dimensional coordinates.
3Measurement precision
If the laser tracker uses a narrow collimated beam to a single target, then measurement accuracy is maintained, but only one reflector can be monitored at a time
Solution Approach 1:
The patent segments the single narrow collimated beam into multiple separate beams using a beam splitting element positioned at the focal point. Each resulting beam maintains the narrow, collimated properties necessary for accurate measurement while directing light to different reflectors simultaneously. This segmentation enables both high measurement precision and increased productivity by allowing parallel measurement of multiple targets.
4Illumination intensity
If the output power of a single beam is increased to extend measurement range, then signal strength improves, but the system becomes unsafe
Solution Approach 1:
The patent divides the measurement beam into multiple components of lower individual power using a beam splitting element. Each beam component maintains sufficient intensity for accurate measurement at extended ranges while the distributed power structure prevents any single beam from reaching hazardous power levels. This segmentation approach simultaneously achieves extended measurement range through increased effective signal strength while maintaining system safety.
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 simultaneous measurement of multiple targets with reduced overall measurement time, increased accuracy, and self-calibration, overcoming the limitations of traditional angle-based systems by using programmable spatial light modulators and retroreflective targets.
Implementation Method 1
The spatial light modulator is configured to accept an input from the computer that programs the pattern of transmission levels to be displayed on the spatial light modulator. The spatial light modulator is operable to modulate light passing through it to produce an intensity pattern
Implementation Method 2
Retroreflective targets are provided on objects to be measured in a measurement space. The light director is configured to direct retroreflected light from the measurement space to the detector
Implementation Method 3
The detector is configured to detect light received from the measurement space. The system uses frequency scanning interferometry for distance determination
Implementation Method 4
The system uses frequency scanning interferometry for distance determination
Data Source
Figure 1
AI summary
A measurement device (120) includes a light director and a spatial light modulator (130). The light director is disposed to direct light to the spatial light modulator (130) and the spatial light modulator (130) is disposed to receive light from the light director and to modulate it to form an intensity pattern. An optical element is disposed to receive light which formed the intensity pattern and is arranged to magnify the intensity pattern into a measurement space. A detector (142) is disposed to detect light reflected from the measurement space.