Lensless Imaging Laser Diode Current Control for Fringe Reduction

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Solution Overview

Problem

Lensless imaging techniques for biological samples face challenges in achieving an improved signal-to-noise ratio and detailed observation due to interference fringes caused by excessive light intensity, which impairs image quality and makes it difficult to identify sample characteristics effectively.

Innovation Solution

A method involving a laser diode with adjustable supply current intensity, where the intensity is optimized below the threshold to minimize transverse interference fringes, allowing for improved image acquisition by adjusting the current to a critical intensity that reduces fringe contrast by at least 25%, enhancing the signal-to-noise ratio and image clarity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a laser diode is supplied with high intensity current to improve illumination, then the illumination intensity increases, but transverse interference fringes appear that deteriorate image quality

Engineering Contradiction:

Improveillumination intensityVSAvoidinterference fringes

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by precisely controlling the supply current intensity of the laser diode to be below the threshold intensity, thereby changing the operating parameters to eliminate interference fringes while maintaining sufficient illumination for image acquisition

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses partial action by supplying the laser diode with current that is sufficient to produce coherent light for diffraction patterns but deliberately kept below the threshold that would cause excessive coherence and interference fringes, achieving the right balance for lensless imaging

Inventive Principle:

Principle #16Partial or excessive action

2Power

If the supply current intensity is increased to improve signal strength, then the signal strength increases, but the signal-to-noise ratio deteriorates due to fringe interference

Engineering Contradiction:

Improvesignal strengthVSAvoidsignal-to-noise ratio

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent changes the operating parameter of supply current intensity to operate in the optimal range below threshold, where sufficient signal strength is obtained while avoiding the noise introduced by interference fringes, thus improving signal-to-noise ratio

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If a laser diode operating above threshold is used to ensure coherent light output, then the coherence is improved, but the transverse interference fringes extend through the image and reduce measurement precision

Engineering Contradiction:

ImprovecoherenceVSAvoidmeasurement precision

Core Design Contradiction:

Stability of the object's compositionVSMeasurement precision

Solution Approach 1:

The patent applies parameter changes by setting the supply current below the threshold value, maintaining sufficient coherence for diffraction-based lensless imaging while eliminating the excessive coherence that causes transverse interference fringes to extend through the image and degrade measurement precision

Inventive Principle:

Principle #35Parameter changes

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 results in higher contrast and more detailed diffraction patterns, improving the quality of images obtained through lensless imaging, enabling better sample characterization and identification with reduced noise interference.

Implementation Method 1

a laser diode that is able to emit an incident light wave, said laser diode being supplied with a supply current, such that a laser effect is obtained when an intensity of said supply current exceeds an intensity termed threshold intensity

Methodology Applied

Scientific EffectLaser effect: Laser

Implementation Method 2

The image is formed of interference patterns between the light wave emitted by the source and transmitted by the sample and diffraction waves resulting from the diffraction, by the sample, of the light wave emitted by the source

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 3

The image is formed of interference patterns between the light wave emitted by the source and transmitted by the sample and diffraction waves resulting from the diffraction

Methodology Applied

Scientific EffectInterference: Interference

Data Source

PatentUS11221290B2Method for observing a sample by lensless imaging

Publication Date: 2022.01.11 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

A method for observing a sample by lensless imaging, in which a sample is positioned between a laser diode and an image sensor, the laser diode being supplied with a supply current whose intensity is less than or equal to a critical value. This critical intensity is determined during preliminary operations, during which the intensity is initially greater than a laser threshold of the diode. By observing the image formed at the image sensor, the intensity is decreased until an attenuation of the interference images on the formed image is observed, the critical intensity corresponding to the intensity at which this attenuation is optimum.