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arxiv: 2605.02873 · v1 · submitted 2026-05-04 · ⚛️ physics.optics · physics.data-an· quant-ph· stat.AP

Recognition: unknown

Fixed-detector tilt--defocus sensing by upstream source coding in a time-reversed Young interferometer

Jianming Wen
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Pith reviewed 2026-05-08 17:28 UTC · model grok-4.3

classification ⚛️ physics.optics physics.data-anquant-phstat.AP
keywords time-reversed Young interferometerbeam tilt sensingdefocus sensingupstream source codingfixed detectorFisher informationdouble-slit modeloptical alignment
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The pith

Two source-coded channels in a time-reversed Young interferometer recover essentially all local Fisher information for tilt and defocus sensing with a fixed detector.

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

The paper establishes that a time-reversed Young interferometer can monitor beam tilt and focus drift simultaneously using a fixed detector by applying upstream source codes to the input. Using a finite-width double-slit Fresnel model, it derives the response functions for tilt-like and defocus-like perturbations and computes optimal codes numerically. These codes are fringe-locked and enable two scalar channels to capture nearly the full local Fisher information available in the complete source-resolved record. This setup is suited for applications needing continuous tracking without downstream wavefront cameras.

Core claim

We propose a physically explicit sensing application of a time-reversed Young (TRY) interferometer: simultaneous monitoring of beam tilt and focus drift with a fixed detector. The task is relevant to compact optical relays, free-space links, fiber-coupling stages, and micro-optical alignment modules, where continuous tracking of pointing and focus is needed but downstream wavefront cameras or multiport analyzers are undesirable. Using a finite-width double-slit Fresnel model, we derive the exact local TRY response functions for tilt-like and defocus-like phase perturbations and compute the corresponding optimal upstream source codes numerically. The physical optimal codes are fringe-locked,

What carries the argument

The time-reversed Young (TRY) interferometer with numerically optimized upstream source codes applied to a finite-width double-slit, where the codes are fringe-locked to enable scalar channel recovery of tilt and defocus information.

Load-bearing premise

The finite-width double-slit Fresnel model accurately captures the physical response to small tilt-like and defocus-like phase perturbations and the optimal upstream codes remain effective in real experiments.

What would settle it

A direct comparison in an optical setup where the Fisher information extracted from two source-coded channels is measured against the full source-resolved TRY record for known small tilt and defocus perturbations; significant shortfall would falsify the recovery claim.

Figures

Figures reproduced from arXiv: 2605.02873 by Jianming Wen.

Figure 1
Figure 1. Figure 1: FIG. 1. Physical TRY response and optimal source codes for view at source ↗
read the original abstract

We propose a physically explicit sensing application of a time-reversed Young (TRY) interferometer: simultaneous monitoring of beam tilt and focus drift with a fixed detector. The task is relevant to compact optical relays, free-space links, fiber-coupling stages, and micro-optical alignment modules, where continuous tracking of pointing and focus is needed but downstream wavefront cameras or multiport analyzers are undesirable. Using a finite-width double-slit Fresnel model, we derive the exact local TRY response functions for tilt-like and defocus-like phase perturbations and compute the corresponding optimal upstream source codes numerically. The physical optimal codes are fringe-locked and differ qualitatively from the simple odd/even modes suggested by Gaussian toy models. Two source-coded scalar channels recover essentially all local Fisher information in the full source-resolved TRY record for the physical model considered here. Compared with downstream direct intensity sensing, TRY provides first-order access to the mixed tilt--defocus task with fixed detection; compared with ideal downstream matched-mode sorting, its advantage is architectural rather than fundamental.

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 / 2 minor

Summary. The manuscript proposes a fixed-detector scheme for simultaneous tilt and defocus sensing using a time-reversed Young (TRY) interferometer. Within a finite-width double-slit Fresnel propagation model, the authors derive exact local response functions to tilt-like and defocus-like phase perturbations, numerically optimize upstream source codes, and conclude that two source-coded scalar channels recover essentially all local Fisher information present in the full source-resolved TRY intensity record. The optimal codes are reported to be fringe-locked and qualitatively distinct from Gaussian toy-model modes. The work positions TRY as providing first-order access to the mixed tilt-defocus task with fixed detection, with an architectural rather than fundamental advantage over downstream matched-mode sorting.

Significance. If the central claim holds under realistic conditions, the approach could simplify continuous alignment monitoring in compact optical relays, free-space links, and micro-optical modules by eliminating the need for downstream wavefront sensors or movable detectors. The explicit derivation of local response functions and the numerical demonstration that fringe-locked codes outperform simple odd/even modes constitute a concrete contribution to source-coded interferometric sensing. However, the significance is currently limited by the absence of validation outside the scalar paraxial model.

major comments (2)
  1. [Model and numerical optimization sections] The central claim that two source-coded channels recover essentially all local Fisher information is demonstrated exclusively inside the scalar finite-width double-slit Fresnel model used both to define the response functions and to perform the numerical optimization. No quantitative assessment is provided of how the recovered information fraction changes when vectorial effects, partial coherence, or non-paraxial terms are included, even though the optimal codes are stated to be qualitatively different from Gaussian modes and therefore potentially sensitive to model mismatch.
  2. [Fisher-information recovery calculation] The manuscript provides no error analysis or Monte-Carlo validation of the Fisher-information recovery under small but finite perturbations, nor does it report the condition number of the response matrix or the singular values that would substantiate the 'essentially all' claim beyond the specific numerical instance shown.
minor comments (2)
  1. [Derivation of response functions] Notation for the upstream source codes and the local response functions should be introduced with explicit equations rather than descriptive text only.
  2. [Figures] Figure captions should state the exact Fresnel-propagation parameters (slit width, separation, propagation distance) used for each plotted intensity pattern.

Simulated Author's Rebuttal

2 responses · 1 unresolved

We thank the referee for the thorough review and valuable comments, which have helped us clarify the scope and robustness of our results. We address each major comment below and have revised the manuscript accordingly where feasible.

read point-by-point responses

  1. Referee: [Model and numerical optimization sections] The central claim that two source-coded channels recover essentially all local Fisher information is demonstrated exclusively inside the scalar finite-width double-slit Fresnel model used both to define the response functions and to perform the numerical optimization. No quantitative assessment is provided of how the recovered information fraction changes when vectorial effects, partial coherence, or non-paraxial terms are included, even though the optimal codes are stated to be qualitatively different from Gaussian modes and therefore potentially sensitive to model mismatch.

    Authors: We agree that the analysis is performed within the scalar paraxial Fresnel model with finite slit width. This model was deliberately selected because it permits an exact, closed-form derivation of the local response functions to tilt and defocus perturbations while retaining the essential double-slit interference physics of the TRY geometry. The numerical optimization of source codes is likewise performed inside this consistent framework. Extending the calculation to vectorial fields, partial coherence, or non-paraxial propagation would require a substantially more elaborate numerical treatment (e.g., full Maxwell solvers or coherence propagation matrices) that lies outside the scope of the present manuscript. We have added a dedicated paragraph in the Discussion section explicitly stating this limitation and noting that the fringe-locked character of the optimal codes may confer some qualitative robustness to small model perturbations, although quantitative sensitivity studies remain an important direction for future work. revision: partial

  2. Referee: [Fisher-information recovery calculation] The manuscript provides no error analysis or Monte-Carlo validation of the Fisher-information recovery under small but finite perturbations, nor does it report the condition number of the response matrix or the singular values that would substantiate the 'essentially all' claim beyond the specific numerical instance shown.

    Authors: The claim that two source-coded channels recover essentially all local Fisher information is based on direct numerical comparison, within the model, between the information matrix obtained from the two optimized codes and the full source-resolved intensity record. To strengthen this statement, we have now computed the singular values of the response matrix and the condition number of the associated Fisher information matrix; these quantities confirm that the two modes capture the dominant eigenvalues with negligible contribution from higher-order singular values. We have also included a short Monte-Carlo section that samples small but finite tilt and defocus perturbations, computes the empirical estimation covariance, and verifies that it saturates the Cramér-Rao bound predicted by the recovered information. These additions appear in the revised Results and Methods sections. revision: yes

standing simulated objections not resolved
  • Quantitative assessment of information recovery under vectorial effects, partial coherence, or non-paraxial propagation, which would require a new and substantially more complex numerical framework.

Circularity Check

0 steps flagged

No significant circularity; numerical results are self-contained within the stated model.

full rationale

The paper derives local response functions from the finite-width double-slit Fresnel model and numerically optimizes upstream codes inside the same model, then reports that two channels recover essentially all Fisher information 'for the physical model considered here.' This is an explicit computational demonstration rather than a first-principles prediction or derivation that reduces to its inputs by construction. No self-citations, uniqueness theorems, or ansatzes are invoked as load-bearing steps. The claim is scoped to the model, so the information-recovery statement follows directly from the numerical evaluation without circular reduction. The derivation chain remains independent of external benchmarks or prior author results.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

The central claim rests on a finite-width double-slit Fresnel diffraction model and the validity of local linear response functions for small phase perturbations; no explicit free parameters, axioms, or invented entities are stated in the abstract.

pith-pipeline@v0.9.0 · 5479 in / 1093 out tokens · 35353 ms · 2026-05-08T17:28:06.709047+00:00 · methodology

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Reference graph

Works this paper leans on

34 extracted references · 3 canonical work pages · 3 internal anchors

  1. [1]

    B. C. Platt and R. Shack , title =. J. Refract. Surg. , year =

  2. [2]

    Kanai and A

    T. Kanai and A. Suda and S. Bohman and M. Kaku and S. Yamaguchi and K. Midorikawa , title =. Appl. Phys. Lett. , year =

  3. [3]

    Rahmani and T

    A. Rahmani and T. Cox and A. T. A. Achary and A. Ponjavic , title =. Opt. Express , year =

  4. [4]

    Zhou and Q

    J. Zhou and Q. He and Y. Qu and D. Zhao and Z. Wu and J. Yang , title =. Appl. Phys. Lett. , year =

  5. [5]

    Kaymak and R

    Y. Kaymak and R. Rojas-Cessa and J. Feng and N. Ansari and M. Zhou and T. Zhang , journal =. 2018 , title =

    2018

  6. [6]

    anen and J. H\

    P. Karioja and J. Ollila and V.-P. Putila and K. Ker\"anen and J. H\"akkil\"a and H. Kopola , title =. 2000 Proceedings. Proc. 50th Electron. Compon. Technol. Conf. (ECTC) , year =

    2000

  7. [7]

    Ishikawa and J

    K. Ishikawa and J. Zhang and A. Tuantranont and V. M. Bright and Y.-C. Lee , title =. Sens. Actuators A Phys. , year =

  8. [8]

    Liu and S

    R. Liu and S. Zhao and P. Zhang and H. Gao and F. Li , title =. Appl. Phys. Lett. , year =

  9. [9]

    Pelzman and S.-Y

    C. Pelzman and S.-Y. Cho , title =. Appl. Phys. Lett. , year =

  10. [10]

    Wen , title =

    J. Wen , title =. Opt. Commun. , year =

  11. [11]

    Wen , title =

    J. Wen , title =. 2026 , journal =

    2026

  12. [12]

    Optimal Null-Constrained Source-Basis Sensing in a Time-Reversed Young Interferometer

    J. Wen , title =. arXiv:2604.10320 , year =

    work page internal anchor Pith review Pith/arXiv arXiv

  13. [13]

    Multi-slit time-reversed Young interference: source-space grating laws, quadratic-phase effects, and Talbot-like revivals

    J. Wen , title =. arXiv:2604.19524 , year =

    work page internal anchor Pith review Pith/arXiv arXiv

  14. [14]

    From Random Fringes to Deterministic Response: Statistical Foundations of Time-Reversed Young Interferometry

    J. Wen , title =. arXiv:2604.23797 , year =

    work page internal anchor Pith review Pith/arXiv arXiv

  15. [15]

    Tsang , title =

    M. Tsang , title =. Physical Review Research , year =

  16. [16]

    Tsang and R

    M. Tsang and R. Nair and X.-M. Lu , title =. Physical Review X , year =

  17. [17]

    Optimal measurements for quantum spatial superresolution , journal =

    J. Optimal measurements for quantum spatial superresolution , journal =. 2018 , volume =

    2018

  18. [18]

    Pellat-Finet , title =

    P. Pellat-Finet , title =. Opt. Lett. , year =

  19. [19]

    R. J. Noll , title =. J. Opt. Soc. Am. , year =

  20. [20]

    R. G. Paxman and T. J. Schulz and J. R. Fienup , title =. J. Opt. Soc. Am. A , year =

  21. [21]

    Roddier and F

    C. Roddier and F. Roddier , title =. J. Opt. Soc. Am. A , year =

  22. [22]

    R. L. Kendrick and D. S. Acton and A. L. Duncan , title =. Appl. Opt. , year =

  23. [23]

    Hickson , title =

    P. Hickson , title =. J. Opt. Soc. Am. A , year =

  24. [24]

    M. A. van Dam and R. G. Lane , title =. J. Opt. Soc. Am. A , year =

  25. [25]

    M. A. van Dam and R. G. Lane , title =. Appl. Opt. , year =

  26. [26]

    Zhang and J

    X. Zhang and J. Zhang and Y. Li and Y. Zhang and J. Zhu , title =. Appl. Phys. Lett. , year =

  27. [27]

    M. A. A. Neil and M. J. Booth and T. Wilson , title =. J. Opt. Soc. Am. A , year =

  28. [28]

    E. N. Ribak and S. M. Ebstein , title =. Opt. Express , year =

  29. [29]

    J. R. Hervas and L. L. S\'anchez-Soto and A. Z. Goldberg and Z. Hradil and J. Optimizing measurement tradeoffs in multiparameter spatial superresolution , journal =. 2024 , volume =

    2024

  30. [30]

    R. M. Clare and R. G. Lane , title =. J. Opt. Soc. Am. A , year =

  31. [31]

    M. R. Grace and Z. Dutton and A. Ashok and S. Guha , title =. J. Opt. Soc. Am. A , year =

  32. [32]

    Wu and P

    T. Wu and P. Berto and M. Guillon , title =. Appl. Phys. Lett. , year =

  33. [33]

    Richter and M

    H. Richter and M. Greiner-B. Terahertz wavefront measurement with a Hartmann sensor , journal =. 2012 , volume =

    2012

  34. [34]

    Liu and B

    M. Liu and B. Dong , title =. Opt. Lasers Eng. , year =