Laser Illumination Device for Homogeneous Depth Mapping
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Solution Overview
Problem
Conventional surveillance systems using stereoscopic cameras face challenges in achieving reliable and homogeneous illumination for accurate depth mapping, particularly in large unstructured areas with similar structural features, leading to errors in distance calculation and potential safety hazards due to inadequate light distribution from existing lighting devices.
Innovation Solution
A lighting device utilizing a laser bar with internal collimating optics and a microlens or prism array to redistribute light into a homogeneous, rectangular illumination field, maintaining spatial coherence and allowing for flexible intensity distribution to compensate for edge losses and ambient light dynamics, while using inexpensive and powerful light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional lamps or LEDs are used to provide high light output, then illumination intensity is improved, but service life is reduced and light distribution uniformity deteriorates
Solution Approach 1:
The patent uses inexpensive laser diodes that can be easily replaced, accepting that they have limited service life. The low cost and ease of replacement compensate for the short operational duration, allowing continuous operation of the illumination system.
Solution Approach 2:
The patent changes the spectral parameter by using laser diodes with specific wavelengths (e.g., 405nm, 450nm, 532nm) and employs optical filters to select narrow frequency bands. This enables differentiation from ambient light and achieves uniform illumination through controlled spectral characteristics.
2Duration of action of stationary object
If laser bars are used to achieve high light output with semiconductor sources, then cost and service life are improved, but illumination field uniformity deteriorates
Solution Approach 1:
The patent introduces diffusers and optical filters as intermediary elements between the laser bar and the monitored area. These intermediaries redistribute the light from the laser bar to create uniform illumination while maintaining the benefits of laser diodes (long service life, low cost, narrow spectrum).
Solution Approach 2:
The patent uses optical filters to select specific narrow frequency bands from the laser bar output, and employs diffusers to change the spatial distribution of light. This transforms the non-uniform laser output into uniform illumination with controlled spectral characteristics.
3Measurement precision
If structured light patterns are projected to generate depth information, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses simple, inexpensive laser diodes and basic optical elements (diffusers, filters) to generate structured light patterns, avoiding complex projector systems. The simplicity of the components compensates for any limitations in pattern generation capability.
Solution Approach 2:
The patent generates structured light patterns by modulating the intensity and position of laser diodes with specific wavelengths, using optical filters to create narrow frequency band patterns. This achieves effective structured light projection through controlled parameter changes rather than complex hardware.
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 provides a high-intensity, homogeneous illumination field with low light losses, enhancing the reliability of depth mapping and reducing errors in surveillance systems, supporting the detection of unauthorized interventions and improving the overall performance of 3D security cameras.
Implementation Method 1
a laser bar (104) with a multiplicity of individual emitter areas (106) arranged in a line in the first axis and with internal collimating optics for collimating light bundles (108) in a second axis, which is perpendicular to the first axis
Implementation Method 2
internal collimating optics for collimating light bundles (108) in a second axis
Implementation Method 3
a microlens array (110) which redistributes the light from the light sources and superimposes individual light bundles (108) from individual emitters (106) in a superimposition direction, in order to form an illumination line (112) with a desired intensity distribution
Implementation Method 4
a prism array (126) which is arranged behind the microlens array (110) in the beam path and which generates a rectangular illumination field (124) with homogeneous intensity distribution through deflection of the illumination line (112)
Implementation Method 5
Semiconductor light sources, on the other hand, have a long service life and make the monitoring task easier than broadband conventional lamps, because the defined, narrow frequency spectrum of their useful light can be distinguished from ambient light by optical filters
Data Source
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AI summary
The device (100) has a micro lens array (110) arranged upstream of light sources (106). The lens array comprises lenses (118) to collimate a light beam emitted from the light source in an axis to generate an illumination line. The lenses are tiltably arranged to each other in the lens array around a tilt angle. A prism field with optical elements is assigned to the lens array, and the optical elements are tilted to each other and comprise different wedge angles to lift the illumination line to an illumination field (124) in another axis transverse to the former axis. Independent claims are also included for the following: (1) three dimensional stereo security camera comprising a lighting device (2) a method for illuminating a monitored area (3) stereoscopic imaging method for producing a dense depth map of a scenery in a monitored area (4) a method for secure three-dimensional monitoring of a spatial area.