Waveguide Diffraction Compensation for Precise Time-of-Flight Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The measurement of time of flight and distance using a measuring light beam is influenced by wavelength-dependent deflection and optical path length variations within a waveguide, leading to inconsistent measurement results.
Innovation Solution
A device comprising a measuring light source, light sensor, and waveguide with a measuring diffraction structure that guides the light beam wavelength-dependently, allowing for precise determination of optical path length and time-of-flight contributions, using polychromatic light to enhance capture region and avoid visible illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a waveguide with diffraction structure is used to guide the measuring light beam, then the capture region is enlarged and the device becomes more compact, but wavelength-dependent deflection causes measurement precision to deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the wavelength-dependent optical path length contributions in a lookup table during the device setup phase. Before actual time of flight measurements, the system determines the wavelength of the measuring light beam and retrieves the corresponding optical path length contribution from the pre-computed lookup table, eliminating the need for real-time complex calculations and compensating for the waveguide's wavelength-dependent deflection effects.
Solution Approach 2:
The patent employs parameter changes by utilizing the wavelength of the measuring light beam as a key parameter to index into the lookup table. By changing the wavelength parameter and correspondingly adjusting the optical path length contribution value retrieved from the lookup table, the system compensates for wavelength-dependent deflection errors and maintains measurement precision across different wavelengths.
2Measurement precision
If monochromatic light is used for time of flight measurement, then measurement precision is improved, but the capture region is limited and visible illumination may be perceived
Solution Approach 1:
The patent applies universality by designing the lookup table to handle multiple wavelengths simultaneously. The same lookup table structure and compensation mechanism work for any wavelength within the supported range, allowing the device to use polychromatic light sources (including invisible infrared wavelengths) while maintaining measurement precision through wavelength-specific compensation values stored in the universal lookup table.
3Ease of operation
If polychromatic light is used to enlarge capture region and avoid visible illumination, then ease of operation is improved, but wavelength-dependent deflection causes measurement precision to worsen
Solution Approach 1:
The patent replaces complex real-time optical path calculations with a pre-computed lookup table stored in memory. Instead of performing complex mechanical or computational operations during measurement, the system simply retrieves pre-calculated compensation values from the lookup table based on the measured wavelength, significantly simplifying the measurement process while maintaining precision.
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 distance measurement with a polychromatic light beam, avoiding wavelength-dependent deflection errors and allowing for a larger capture region while maintaining user-friendliness and cost-effectiveness.
Implementation Method 1
The waveguide comprises a measuring diffraction structure for wavelength-dependent deflection of the measuring light beam
Implementation Method 2
the waveguide is designed to guide the measuring light beam emitted by the measuring light source to an object situated in an object region of the device and the measuring light beam reflected off the object to the light sensor at least partially through the waveguide
Data Source
AI summary
A device for measuring a time of flight of a measuring light beam, comprising a measuring light source for emitting the beam, a light sensor for detecting the beam, a waveguide, and a data processing device. The waveguide is designed to guide the beam emitted by the measuring light source to an object situated in an object region of the device and the beam reflected off the object to the light sensor at least partially through the waveguide, wherein the waveguide includes a measuring diffraction structure for wavelength-dependent deflection of the beam and wherein the beam traverses a wavelength-dependent path length in the waveguide. The data processing device is configured to determine, when measuring the time of flight, an optical path length contribution and/or a time-of-flight contribution for the beam detected by the light sensor, taking into account the wavelength-dependent path length of the beam within the waveguide.