LCOS Structured Light Projection for Precise Low-Power Depth Sensing
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Solution Overview
Problem
Existing depth cameras suffer from high power consumption, large size, and poor anti-interference ability, limiting their capability for fine real-time imaging and high-precision depth data measurement.
Innovation Solution
The use of Liquid Crystal on Silicon (LCOS) for precise projection of structured light, combined with Vertical Cavity Surface Emitting Laser (VCSEL) for low power consumption and miniaturization, along with multiple sub-image sensors for fast imaging and synchronization, enhances imaging accuracy and adaptability to various scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If traditional depth camera structures are used, then depth measurement function is achieved, but power consumption is high and device size is large
Solution Approach 1:
The patent changes the wavelength parameter of the light source to infrared band (780nm-1100nm), which allows for lower power consumption while maintaining measurement precision. The infrared light is less affected by ambient visible light interference, enabling accurate depth measurement with reduced power requirements compared to visible light systems.
Solution Approach 2:
The patent replaces traditional mechanical scanning systems with a spatial light modulator (SLM) that uses liquid crystal technology to modulate the projected light pattern. This substitution eliminates moving parts, reduces power consumption, and enables precise control of the structured light projection without the mechanical complexity of traditional systems.
2Measurement precision
If traditional projection systems are used, then structured light can be projected, but imaging accuracy for fine details is insufficient
Solution Approach 1:
The patent introduces a spatial light modulator (SLM) as an intermediary component between the infrared light source and the projection lens. The SLM modulates the infrared light to create precise structured light patterns (stripes, grids, or random patterns) that encode depth information, enabling high-resolution depth mapping without complex mechanical projection systems.
Solution Approach 2:
The patent employs periodic modulation of the structured light patterns through the SLM, projecting sequences of patterns (e.g., alternating stripe patterns or time-varying phase patterns) that allow the imaging system to capture depth information through temporal encoding. This periodic action enables precise measurement of fine details by comparing phase shifts or pattern deformations over time.
3Measurement precision
If high-resolution imaging is achieved, then fine details can be captured, but real-time imaging capability is compromised
Solution Approach 1:
The patent pre-calculates and stores multiple structured light patterns (such as phase-shifted stripe patterns or coded aperture patterns) before the measurement process begins. During real-time imaging, these pre-prepared patterns are rapidly projected in sequence, allowing the system to capture high-resolution depth data without the computational overhead of generating patterns on-the-fly, thus maintaining real-time imaging capability.
Solution Approach 2:
The patent divides the imaging process into multiple segments by projecting different structured light patterns (e.g., dividing the field of view into multiple regions or using multiple frequency components). Each pattern captures specific depth information, and the results are integrated to reconstruct the complete high-resolution depth map. This segmentation allows parallel processing and reduces the time required for full-resolution imaging.
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 achieves improved imaging accuracy, reduced power consumption, and miniaturization, enabling high-precision depth data measurement, especially suitable for tiny objects and real-time detection of moving objects.
Implementation Method 1
a laser configured to generate laser light; an LCOS (Liquid Crystal on Silicon) element configured to receive the laser light and generate the structured light for projection
Implementation Method 2
the LCOS element is configured to control the reflection of the light by adjusting the phase difference of the liquid crystal corresponding to each pixel
Implementation Method 3
the characteristics of VCSEL can be used to generate polarized light
Data Source
AI summary
Disclosed is a depth data measuring device comprising a structured light projection unit and an imaging unit. The projection unit includes a laser generator and an LCOS (Liquid Crystal on Silicon) element for generating structured light to illuminate a subject. The LCOS enables fine projection and supports various patterns (e.g., speckles, stripes), enhancing depth imaging accuracy across scenarios. Integration with a VCSEL structure reduces power consumption and allows miniaturization. Additionally, multiple photosensitive units sharing part of the optical path are introduced to shorten the imaging time required for multi-frame depth calculation, thereby improving the frame rate.