VCSEL Light Source for Gated 3D Camera
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Solution Overview
Problem
Conventional gated 3D cameras face accuracy issues due to wavelength shifts in light source spectra caused by temperature changes, leading to misalignment with the camera shutter's contrast ratio function, which results in reduced normalized contrast intensity and increased bias errors in distance measurements.
Innovation Solution
A modified VCSEL light source with a broadened laser cavity is used, providing improved matching with the camera shutter and reducing temperature-induced wavelength shifts, thereby increasing the normalized contrast intensity and minimizing bias errors. The VCSEL light source has a wider spectrum and is less sensitive to temperature changes, ensuring accurate distance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional light source is used in a gated 3D camera, then the device can operate, but temperature changes cause wavelength shifts that misalign with the shutter's contrast ratio function, reducing measurement accuracy
Solution Approach 1:
The patent modifies the VCSEL light source parameters, specifically broadening the laser cavity to widen the emission spectrum. This parameter change makes the light source less sensitive to temperature-induced wavelength shifts, maintaining better alignment with the shutter's contrast ratio function across varying temperatures, thereby improving measurement accuracy and reliability
Solution Approach 2:
The patent applies prior cushioning by pre-broadening the VCSEL spectrum through cavity design modifications before temperature changes occur. This proactive approach creates a buffer that absorbs the effects of temperature-induced wavelength shifts, ensuring the light source remains matched to the shutter's contrast ratio function without requiring active compensation during operation
2Measurement precision
If the light source spectrum is narrowed for high intensity, then the normalized contrast intensity increases, but the light source becomes more sensitive to temperature-induced wavelength shifts
Solution Approach 1:
The patent changes the spectral parameter of the VCSEL by broadening the laser cavity, achieving a wider emission spectrum. This allows the light source to maintain high normalized contrast intensity while simultaneously reducing sensitivity to temperature changes, as the broader spectrum provides a larger margin for wavelength shifts without losing alignment with the shutter's contrast ratio function
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 modified VCSEL light source enhances the accuracy of distance measurements by maintaining a high normalized contrast intensity and reducing bias errors, even under temperature fluctuations, resulting in improved spatial accuracy and reliability for gated 3D cameras.
Implementation Method 1
a light source comprising a VCSEL controllable to illuminate the scene with a train of pulses of light having a characteristic spectrum
Implementation Method 2
wavelength shifts in light source spectra caused by temperature changes
Implementation Method 3
a gating means for gating the camera open and closed, such as an optical shutter or a gated image intensifier
Implementation Method 4
a camera having a photosensitive surface, hereinafter referred to as a 'photosurface'
Data Source
AI summary
A camera for determining distances to a scene, the camera comprising: a light source comprising a VCSEL controllable to illuminate the scene with a train of pulses of light having a characteristic spectrum; a photosurface; optics for imaging light reflected from the light pulses by the scene on the photosurface; and a shutter operable to gate the photosurface selectively on and off for light in the spectrum.