Band-Pass Filter Coating for Wide-Angle Range Imaging
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Solution Overview
Problem
Existing range imaging devices, such as ToF sensors, are susceptible to background light interference, especially in wide-angle applications, leading to reduced accuracy and increased complexity, making them bulky, sensitive to environmental factors, and requiring trained operators.
Innovation Solution
A range imaging module with a band-pass filter coating on a cover in the collimated beam region, combined with an imaging unit, effectively blocks unwanted background light by minimizing angle of incidence variations, allowing for a narrow band-pass filter and reducing refractive power impact, resulting in a compact, user-friendly device with maintained accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a wide-angle optical system is used with a ToF sensor, then the field-of-view is increased, but the susceptibility to background light increases
Solution Approach 1:
A band-pass filter is introduced as an intermediary component between the wide-angle objective lens and the ToF sensor. This filter selectively transmits only the wavelength range of the distance measurement radiation while blocking background light, thereby enabling wide-angle operation without increased susceptibility to background light interference.
2Measurement precision
If a narrow band-pass filter is used to block background light, then the filtering precision is improved, but the refractive power variations across the field-of-view increase
Solution Approach 1:
The band-pass filter is designed with specific optical parameters (wavelength range, transmission characteristics) that are optimized for the wide-angle application. By carefully selecting and controlling these parameters, the filter achieves high background light rejection while maintaining acceptable refractive power stability across the entire field-of-view.
3Measurement precision
If a high-end laser scanner is used, then the coordinate measuring accuracy is improved, but the device complexity and size increase
Solution Approach 1:
The patent replaces complex mechanical laser scanning systems with a stationary ToF sensor combined with a wide-angle objective lens and band-pass filter. This substitution eliminates moving parts and complex mechanical deflection mechanisms while maintaining coordinate measuring accuracy through the optical filtering approach.
4Measurement precision
If a high-end laser scanner is used, then the coordinate measuring accuracy is improved, but the ease of operation deteriorates
Solution Approach 1:
The system performs automatic background light filtering through the band-pass filter, eliminating the need for trained operators to manually adjust or calibrate complex scanning parameters. The device captures 3D measurement data automatically with a simple snapshot operation, making it accessible to untrained users while maintaining high accuracy.
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
The solution significantly reduces susceptibility to background light, enabling high-accuracy 3D measurement data generation with reduced technical complexity, facilitating handling by untrained operators and achieving a smaller, lighter device while maintaining coordinate measuring accuracies.
Implementation Method 1
A range imaging module with a band-pass filter coating on a cover in the collimated beam region, combined with an imaging unit, effectively blocks unwanted background light
Implementation Method 2
The range imaging receiver is configured to provide for each of the detection elements a distance measurement based on a time-of-flight measuring principle using the distance measurement radiation
Implementation Method 3
Acquisition of 3D measurement data by a reality capture device typically involves use of a laser scanner emitting a laser measurement beam, e.g. using pulsed electromagnetic radiation
Data Source
AI summary
A range imaging module and a reality capture device comprising a range imaging module and configured to generate 3D measurement data for generating a digital representation of an environment. The range imaging module comprises a cover, which is transparent for at least part of distance measurement radiation of the range imaging module and which comprises a band-pass filter coating. The cover with the band-pass filter coating is arranged in a collimated beam region outside an imaging unit of the range imaging module and encloses the imaging unit, so that returning distance measurement radiation from an imaging field of view of the imaging unit first passes the cover with the band-pass filter coating and then the imaging unit.