Optical Transfer Function Simulation via Phase Screens
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Solution Overview
Problem
Current physics-based image simulation methods, such as sequential ray tracing, are cumbersome for capturing phase information due to the short wavelength of light and are inefficient in handling diffraction effects, particularly in nighttime multi-spectral imaging where laser illumination introduces coherent speckle that hinders precise spectral analysis.
Innovation Solution
A method for computationally simulating optical images using computed phase screens to generate a simulated scene with variable optical properties, computing optical transfer functions (OTFs) as a sum of separable OTFs, and convolving these OTFs with the scene to simulate electromagnetic fields, thereby accounting for phase and polarization effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sequential ray tracing is used for physics-based image simulation, then the simulation can be implemented, but it is cumbersome to capture phase information and diffraction effects due to the short wavelength of light
Solution Approach 1:
The patent replaces the mechanical sequential ray-tracing approach with a wave-optics-based computational model that directly computes phase and diffraction effects using electromagnetic field equations, eliminating the need for complex ray-by-ray phase tracking
Solution Approach 2:
The patent changes the fundamental simulation parameters from geometric optics (ray paths) to wave optics (electromagnetic fields, phase, wavelength), enabling direct computation of phase information and diffraction effects without the limitations of ray tracing
2Reliability
If sequential ray tracing is used for simulation, then the implementation is possible, but it is inefficient in capturing diffraction effects which are typically important for imaging
Solution Approach 1:
The patent substitutes the ray-tracing mechanical model with a wave-optics computational model that inherently captures diffraction effects through electromagnetic field propagation equations, providing both accuracy and efficiency
Solution Approach 2:
The patent performs preliminary computation of the optical transfer function (OTF) that encapsulates diffraction effects, allowing these effects to be applied efficiently to the entire image rather than computing them individually for each ray
3Use of energy by moving object
If laser illuminators are used for nighttime multi-spectral imaging, then energy-efficient illumination at mission-specific wavelengths is provided, but coherent speckle effects impede precise spectral analysis
Solution Approach 1:
The patent converts the harmful speckle effects into a beneficial simulation capability by computing speckle patterns through electromagnetic field propagation, allowing speckle to be modeled and potentially mitigated in the simulation process while maintaining laser illumination efficiency
Solution Approach 2:
The patent introduces an electromagnetic field propagation model as an intermediary between laser illumination and image formation, allowing speckle effects to be computed and analyzed separately from the illumination source, enabling spectral analysis to be performed on the underlying signal without speckle interference
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
This approach provides a more efficient and accurate simulation of optical images, effectively mitigating the challenges of diffraction and speckle noise, enabling improved system design and performance prediction in multi-spectral and hyperspectral imaging.
Implementation Method 1
Another drawback of sequential ray tracing is that it is cumbersome to capture phase effects of diffraction which is typically important for imaging
Implementation Method 2
determining fine-scale EM phase modulation of the roughness phase texture
Implementation Method 3
determining fine-scale EM polarization modulation of the polarization texture
Data Source
AI summary
Systems and methods for computationally simulating an optical image are provided. The systems and methods generate a simulated scene having at least one variable optical property, compute an optical transfer function (OTF) via at least one computed phase screen, express the OTF as a sum of at least one separable OTF, convolve the at least one separable OTF with the simulated scene to simulate electromagnetic (EM) fields of the optical image, and compute image intensities of the optical image from the simulated EM fields of the optical image.