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arxiv: 2604.24168 · v1 · submitted 2026-04-27 · ⚛️ physics.optics

Sub-acoustic resolution photoacoustic imaging through scattering layers using speckle correlations

Benjamin Keenlyside , Arnon A.B. , Dylan Marques , Ivo Vellekoop , James Guggenheim This is my paper

Pith reviewed 2026-05-08 02:06 UTC · model grok-4.3

classification ⚛️ physics.optics
keywords photoacoustic imagingspeckle correlationsscattering mediasub-acoustic resolutionoptical imaging through scatteringspeckle translationdiffuser imagingacoustic-optical hybrid
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The pith

Controlled speckle translations with photoacoustic detection recover optical-resolution images through scattering layers at sub-acoustic scales.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper demonstrates that translating a speckle illumination pattern in a controlled manner and detecting the resulting photoacoustic signals allows reconstruction of an object's optical absorption at optical resolution. This works inside regions selected by acoustic focusing, even when light has scattered through an opaque diffuser. The approach sidesteps the usual short decorrelation distance of speckles by using the acoustic signal as a stable reference, yielding a field of view several millimeters across. A reader would care because conventional photoacoustic imaging is stuck at acoustic diffraction limits and pure optical methods fail in turbid media; this hybrid offers a concrete route past both constraints.

Core claim

Combining controlled speckle translations with photoacoustic signal detection enables the recovery of optical resolution images within acoustically selected regions, while overcoming the strict decorrelation range limitations of other speckle correlation techniques. In proof-of-concept experiments, objects hidden behind an opaque diffuser are imaged at sub-acoustic diffraction limited resolution of less than 11 micrometers over a field of view exceeding 5 square millimeters, much larger than the effective speckle decorrelation range.

What carries the argument

The correlation between photoacoustic signals produced by successively translated speckle patterns, which encodes the object's optical absorption map at optical resolution inside an acoustically localized volume.

If this is right

  • Objects hidden behind scattering layers can be imaged at optical rather than acoustic resolution.
  • The usable field of view can exceed the speckle decorrelation range by using acoustic selection.
  • High-resolution optical absorption maps become possible in multiple-scattering regimes where direct optical imaging fails.
  • The method works with coherent illumination and acoustic detection without requiring phase conjugation or wavefront shaping.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • If medium dynamics remain stable enough for repeated speckle translations, the approach could be extended to thicker biological tissues.
  • The technique might be combined with existing photoacoustic tomography systems to add optical-resolution sub-volumes inside larger acoustic images.
  • Real-time operation would require fast, repeatable speckle translation methods that preserve the correlation properties demonstrated here.

Load-bearing premise

That controlled translations of the speckle pattern can be maintained across the field of view and that the resulting photoacoustic signal correlations remain usable for reconstruction without being destroyed by medium dynamics or decorrelation.

What would settle it

A measurement in which the speckle pattern is translated across the claimed field of view but the photoacoustic signals lose all correlation beyond the short decorrelation length, leaving reconstructed resolution no better than the acoustic diffraction limit.

read the original abstract

Optical scattering presents a major obstacle to high resolution imaging in biological tissue and other turbid media. Conventional photoacoustic imaging can partially overcome this obstacle, enabling imaging of optical absorption in the multiple-scattering regime, but its resolution remains limited by acoustic diffraction. In this work we explore a strategy to overcome this limit by exploiting correlations in the illumination patterns produced by coherent scattered light. Combining controlled speckle translations with photoacoustic signal detection, this method enables the recovery of optical resolution images within acoustically selected regions, while overcoming the strict decorrelation range limitations of other speckle correlation techniques. In proof-of-concept experiments, we demonstrate imaging of objects hidden behind an opaque diffuser at sub-acoustic diffraction limited (<11um) resolution, over a >5mm^2 field of view much larger than the effective speckle decorrelation range. These results suggest that speckle correlation based photoacoustic imaging may offer a route to high resolution imaging of optical absorption under scattering conditions where conventional optical or photoacoustic techniques are fundamentally limited.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 1 minor

Summary. The manuscript claims that controlled translations of speckle illumination patterns, combined with photoacoustic detection, enable recovery of optical-resolution images inside acoustically gated regions through scattering media. This overcomes the strict decorrelation-range limits of prior speckle-correlation methods. Proof-of-concept experiments are reported to achieve sub-acoustic resolution (<11 μm) imaging of objects hidden behind an opaque diffuser over a >5 mm² field of view.

Significance. If the experimental results are reproducible, the work would represent a meaningful advance in hybrid optical-acoustic imaging by relaxing the field-of-view constraint that has limited speckle-correlation techniques while retaining acoustic depth selection. This could open routes to higher-resolution absorption imaging in turbid biological samples where pure optical methods fail and conventional photoacoustics remain diffraction-limited.

major comments (2)
  1. [Abstract] Abstract: the central claim that the demonstrated FOV (>5 mm²) is 'much larger than the effective speckle decorrelation range' is load-bearing for the novelty assertion, yet the text supplies no quantitative correlation-coefficient data versus translation distance, no measured decay length, and no bound on translation precision or residual phase noise across the field.
  2. [Abstract] Abstract: the reported sub-acoustic resolution (<11 μm) and successful reconstruction rest on the assumption that PA-signal correlations remain usable after controlled speckle shifts, but the abstract provides no description of controls, error bars, data-processing pipeline, or how medium dynamics were ruled out; these omissions prevent verification of the weakest assumption identified in the stress test.
minor comments (1)
  1. [Abstract] Abstract: the acoustic diffraction limit against which the <11 μm resolution is compared should be stated explicitly (including transducer frequency or effective aperture) to allow direct evaluation of the improvement factor.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their careful review and valuable comments on our manuscript. We address each major comment below and have revised the abstract to better support the claims with references to the quantitative data and methods in the main text.

read point-by-point responses

  1. Referee: [Abstract] Abstract: the central claim that the demonstrated FOV (>5 mm²) is 'much larger than the effective speckle decorrelation range' is load-bearing for the novelty assertion, yet the text supplies no quantitative correlation-coefficient data versus translation distance, no measured decay length, and no bound on translation precision or residual phase noise across the field.

    Authors: We acknowledge the referee's observation regarding the abstract. We have revised the abstract to include a statement that the FOV exceeds the effective speckle decorrelation range, as supported by quantitative measurements of the correlation coefficient versus translation distance presented in the main text, along with details on the measured decay length and experimental bounds on translation precision and phase noise. revision: yes

  2. Referee: [Abstract] Abstract: the reported sub-acoustic resolution (<11 μm) and successful reconstruction rest on the assumption that PA-signal correlations remain usable after controlled speckle shifts, but the abstract provides no description of controls, error bars, data-processing pipeline, or how medium dynamics were ruled out; these omissions prevent verification of the weakest assumption identified in the stress test.

    Authors: We acknowledge that the abstract does not elaborate on the controls and processing details. These are provided in the Methods section of the manuscript, including the data-processing pipeline, error bars from repeated measurements, and controls to rule out medium dynamics. We have revised the abstract to briefly outline the approach used to ensure PA-signal correlations remain usable after speckle shifts. revision: yes

Circularity Check

0 steps flagged

No circularity: experimental method with proof-of-concept demonstration

full rationale

The paper describes an experimental technique that combines controlled speckle translations with photoacoustic signal detection to achieve sub-acoustic resolution imaging through scattering media. Claims rest on physical implementation and measured results in proof-of-concept experiments rather than any mathematical derivation chain, first-principles predictions, or equations that reduce to fitted inputs or self-citations. No load-bearing steps invoke self-referential definitions, renamed empirical patterns, or uniqueness theorems from prior author work; the central result is a demonstrated capability over a large FOV, supported directly by the experimental setup and data.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The central claim rests on the physical assumption that coherent scattered light produces controllable, translatable speckle patterns whose correlations with photoacoustic signals can be inverted to recover optical absorption at sub-acoustic scales. No free parameters, invented entities, or non-standard axioms are explicitly introduced in the abstract.

axioms (2)
  • domain assumption Scattered coherent light produces stable, controllable speckle patterns that can be translated without destroying correlation information over the imaging field of view.
    Invoked to justify overcoming decorrelation-range limits of prior speckle techniques.
  • domain assumption Photoacoustic signals linearly encode the optical absorption modulated by the moving speckle illumination.
    Required for the correlation-based reconstruction to recover absorption maps.

pith-pipeline@v0.9.0 · 5482 in / 1386 out tokens · 81432 ms · 2026-05-08T02:06:24.697512+00:00 · methodology

discussion (0)

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Reference graph

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