Pseudo Thermal Light Source for Speckle-Free Ghost Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional ghost imaging technologies face limitations with quantum and classical light sources, including low intensity, speckle formation, crosstalk, and high costs, making it difficult to achieve high temporal coherence and range sensing effectively.
Innovation Solution
A pseudo thermal light source using a resonator type laser diode with controlled temperature and current, generating a laser beam with second-order coherence greater than 2, and employing a beam splitter, spatial light modulator, and temporal correlator for imaging and range sensing without ground glass or modulation devices, reducing noise and speckle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If quantum-entangled light is used for ghost imaging, then strong imaging against external noise is achieved, but the intensity of the quantum light is limited
Solution Approach 1:
The patent changes the fundamental parameters of the light source by using a pseudo thermal light source with second-order coherence instead of quantum-entangled light, enabling both high intensity and noise resistance through classical light with controlled coherence properties
2Stability of the object's composition
If ground glass is used to generate pseudo thermal light source, then temporal coherence is achieved, but the rotation speed is limited causing linewidth of several microseconds and speckle formation
Solution Approach 1:
The patent extracts and eliminates the ground glass component from the system, using a laser diode with controlled coherence properties instead, which removes the mechanical rotation limitation and speckle formation while maintaining temporal coherence
Solution Approach 2:
The patent replaces the mechanical rotation of ground glass with an electronic/optical control system using a laser diode and coherence control unit, eliminating mechanical speed limitations and speckle issues
3Stability of the object's composition
If narrow-band wavelength filter is applied to broad-band spontaneous emission signal, then temporal coherence is improved, but the intensity is lowered and expensive single photon detector is required
Solution Approach 1:
The patent performs preliminary coherence control by adjusting the laser diode's operating conditions (current, temperature) before the light reaches the imaging system, eliminating the need for post-generation filtering that would reduce intensity
Solution Approach 2:
The patent changes the approach from spectral filtering to direct coherence control by adjusting laser diode parameters (current, temperature, injection level) to achieve the desired second-order coherence without intensity loss
4Ease of operation
If laser beam is split into two beams, then ghost imaging is enabled, but there is no second order coherence between the two beams requiring pulsed laser or modulation
Solution Approach 1:
The patent makes the light source universal by generating second-order coherence in the original beam that is then distributed to both imaging paths, enabling both ghost imaging and range sensing without requiring separate coherence generation for each beam
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
Enables high-resolution imaging and range sensing with narrow-band spontaneous emission, avoiding noise and speckle, and allowing single-pixel ghost imaging with improved temporal coherence and reduced costs.
Implementation Method 1
a resonator type laser diode... generating a laser beam with second-order coherence greater than 2
Implementation Method 2
a beam splitter configured to split a laser beam emitted from the pseudo thermal light source into a first beam and a second beam
Implementation Method 3
a temporal correlator configured to infer a target range to an object through temporal coherence between the first beam and the second beam
Data Source
AI summary
An apparatus for pseudo thermal light source ghost imaging and range sensing using narrow-band spontaneous emission includes: a pseudo thermal light source including a resonator type laser diode; a temperature controller configured to control a temperature of the pseudo thermal light source; a current controller configured to control a current of the pseudo thermal light source; a beam splitter configured to split a laser beam emitted from the pseudo thermal light source into a first beam and a second beam; and a temporal correlator configured to infer a target range to an object through temporal coherence between the first beam and the second beam, wherein the pseudo thermal light source oscillates a laser beam having second order coherence when a specific current is applied according to temperature.