Scannerless 3D Imaging Using Loss Modulation
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Solution Overview
Problem
Previous scannerless laser ranging systems using amplitude-modulated continuous-wave lasers are limited by image intensifier tubes, which restrict operation to visible wavelengths, are not eye-safe, and suffer from poor resolution and blooming issues due to high intensity light, limiting their application in fields like vehicle collision avoidance and industrial inspection.
Innovation Solution
A scannerless 3-D imaging apparatus utilizing a loss modulator instead of an image intensifier tube, allowing optical imaging directly onto an array detector, which provides sharper images, eliminates blooming, and extends the wavelength range to eye-safe regions (1.4-1.7 μm), enabling safer and more effective laser operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an image intensifier tube is used in the receiver, then the system can detect backscattered light, but the operation is limited to visible wavelengths and below one micron, and the system is not eye-safe
Solution Approach 1:
The patent changes the operating wavelength parameter from visible light to infrared wavelengths (1.4-1.7 μm), which are eye-safe. This is achieved by replacing the image intensifier tube with a loss modulator and array detector combination that can detect infrared backscattered light, thereby expanding the wavelength range while eliminating eye safety concerns
Solution Approach 2:
The patent replaces the mechanical/image-based detection system (image intensifier tube) with an optical modulation system (loss modulator). The loss modulator uses optical loss modulation rather than image intensification, enabling detection at infrared wavelengths where image intensifier tubes cannot operate
2Measurement precision
If an image intensifier tube is used in the receiver, then the system can operate as a scannerless laser ranging system, but the resolution of target features is poor and blooming occurs in the presence of high intensity light
Solution Approach 1:
The patent replaces the image intensifier tube with a loss modulator that modulates optical loss rather than intensifying images. This substitution eliminates the blooming effect inherent in image intensifier tubes and provides sharper target feature resolution through direct optical imaging onto the array detector
Solution Approach 2:
The patent extracts and removes the image intensifier tube from the system, taking out the source of blooming and poor resolution. By eliminating this component and replacing it with a loss modulator, the harmful blooming effect is removed while maintaining the scannerless operation capability
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 improved image resolution, eliminates blooming, and allows operation at eye-safe wavelengths, expanding applications to include vehicle collision avoidance, robotic vision, and industrial inspection by using a loss modulator with an array detector to construct 3-D images.
Implementation Method 1
a loss modulator which is modulated at the same frequency f0 in response to a second sinusoidal modulation signal having a variable phase delay with respect to the first sinusoidal modulation signal, with the loss modulator being adapted to receive light backscattered from the target within the field of view and to provide a loss in transmission through the loss modulator which is range dependent and phase-delay dependent
Implementation Method 2
an array detector to detect the backscattered light transmitted through the loss modulator and generate therefrom an electrical output signal containing information wherefrom the 3-D image of the target can be constructed
Implementation Method 3
a continuously-emitting light source which is amplitude modulated in response to a first sinusoidal modulation signal at a frequency f0 to provide a non-scanned illumination of the field of view
Data Source
AI summary
A scannerless 3-D imaging apparatus is disclosed which utilizes an amplitude modulated cw light source to illuminate a field of view containing a target of interest. Backscattered light from the target is passed through one or more loss modulators which are modulated at the same frequency as the light source, but with a phase delay δ which can be fixed or variable. The backscattered light is demodulated by the loss modulator and detected with a CCD, CMOS or focal plane array (FPA) detector to construct a 3-D image of the target. The scannerless 3-D imaging apparatus, which can operate in the eye-safe wavelength region 1.4-1.7 μm and which can be constructed as a flash LADAR, has applications for vehicle collision avoidance, autonomous rendezvous and docking, robotic vision, industrial inspection and measurement, 3-D cameras, and facial recognition.