REVIEW 4 major objections 4 minor 31 references
Gaussian beam Radon transform for tensor fields in $\mathbb{R}^2$
T0 review · 4 major / 4 minor · reviewed 2026-08-27 · deepseek-v4-flash
Pith's one-line read The paper establishes that a compactly supported smooth vector field in the unit disk is uniquely recoverable from its longitudinal and transverse Gaussian beam Radon transforms, and a symmetric 2-tensor field from longitudinal…
desk verdict Genuine extension of Gaussian-beam Radon tomography to tensor fields, but every recovery theorem divides by unproved Mellin transform factors and unproved determinants; the central results are not closed as written. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The mechanism that carries the proof is the Fourier-Mellin decomposition of the Gaussian beam kernel. The kernel $K(x_1,x_2)=w_0/w(x_2)\exp(-x_1^2/w^2(x_2))$ has the Fourier symbol $\widehat K(\sigma,\theta^\perp\cdot x)=w_0\sqrt{\pi}\exp(-w_0^2(1+((\theta^\perp\cdot x)/z_R)^2)\sigma^2/4)$. After Fourier transform in the offset $s$ and Fourier series in the beam angle $\theta$, the remaining radial integrals have the form $\int_0^\infty h_n(r)g_n(r^{-1}\sigma^{-1})\,rdr$, a Mellin convolution. The Mellin transform turns this into the product $Nh_n(\rho+2)Ng_n(\rho)$. The problem of inverting the GbRt therefore reduces to dividing by $Ng_n(\rho-2)$ or, for moment data, to solving small linear systems in those Mellin products. This is the deconvolution identity at the center of all four theorems.
What would settle it
Evaluate $Ng_n(\rho-2)$ numerically for small $n$ and for the strip of $\rho$ where the inverse Mellin transform runs, and evaluate the determinants of the systems in (17) and (33)–(34). A zero in any divisor, or a nonzero compactly supported field whose longitudinal and transverse GbRt data vanish identically, would disprove the corresponding recovery theorem.
Extended reading notes
Core claim
The paper's central claim is that the generalized Gaussian beam Radon transforms defined in Definition 3, $$M_k^\ell f(s,\$\theta$)=\int_{\mathbb{R}^2}(\$\theta$^\perp\cdot x)^k K(s-\$\theta$\cdot x,\$\theta$^\perp\cdot x)\langle \$\theta$^\ell(\$\theta$^\perp)^{m-\ell},f(x)\rangle\,dx$$, can be inverted in the following combinations. Theorem 1: every $f\in C_c^\infty(S^1;D)$ is uniquely recovered from $(Lf,Tf)$; after a Fourier transform in $s$ and a Fourier series in $\theta$, the Mellin transform of the angular coefficient $(f_1)_n+i(f_2)_n$ (and similarly $(f_1)_n-i(f_2)_n$) equals a data term divided by $Ng_n(\rho-2)$, and inverse Mellin transform recovers the field. Theorem 2 recovers a vector field from $(Lf,L_1f)$ or from $(Tf,T_1f)$. For symmetric 2-tensor fields, Theorem 3 recovers $f$ from $(Lf,Tf,Mf)$, and Theorem 4 recovers $f$ from $(Lf,L_1f,L_2f)$ or $(Tf,T_1f,T_2f)$ by solving a $2\times2$ linear system whose coefficients are products of Mellin transforms of the kernel coefficients $g_n$; Remark 3.1 shows $(Mf,M_1f,M_2f)$ is insufficient.
Load-bearing premise
The load-bearing premise is that none of the Mellin-transform divisors the inversion divides by—the kernel coefficients $Ng_n(\rho-2)$ and the determinants of the $2\times2$ systems in (17) and (33)–(34)—ever vanish on the range of integration; the paper assumes this instead of proving it.
Editorial extensions
If this is right
- For vector fields, longitudinal and transverse Gaussian beam data determine the field completely, so two measurement scans contain the full information and no third transform is needed.
- For symmetric 2-tensor fields, either three transform types $(Lf,Tf,Mf)$ or three moments of one type $(Lf,L_1f,L_2f)$ determine the field, while the mixed triple $(Mf,M_1f,M_2f)$ does not.
- The Fourier-Mellin formulas give a concrete reconstruction procedure for each proven pair: Fourier transform the data in $s$, expand in Fourier series in $\theta$, divide by kernel-coefficient Mellin transforms, and apply inverse Mellin transforms.
- The authors expect the same divide-by-$Ng_n$ structure to extend to tensor fields of any order, with the calculations growing cumbersome rather than changing in principle.
Reading between the lines
- Because the inversion divides by $Ng_n(\rho-2)$, the numerical conditioning of any implementation depends on how close these divisors come to zero; testing that numerically is a concrete next step.
- The failure of mixed moments to give full recovery in Remark 3.1 mirrors the classical kernel of mixed ray transforms, suggesting the minimal data sets for Gaussian-beam tensor tomography likely match the classical minimal data sets.
- If a zero of $Ng_n(\rho-2)$ is found, the affected transform pair would have non-injective behavior at specific frequencies, and a different extra datum such as one mixed moment might restore uniqueness.
Signed reviews
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper defines generalized Gaussian beam Radon transforms (longitudinal, transverse, mixed, and their integral moments) for vector fields and symmetric 2-tensor fields in R^2, extending the scalar Gaussian beam Radon transform of Roy, Jeon, and Moon. The main results are four recovery theorems: Theorem 1 recovers a compactly supported smooth vector field from its longitudinal and transverse GbRts; Theorem 2 from either (Lf, L1f) or (Tf, T1f); Theorem 3 recovers a symmetric 2-tensor field from (Lf, Tf, Mf); and Theorem 4 from either (Lf, L1f, L2f) or (Tf, T1f, T2f). The proofs proceed by Fourier transforming in the beam coordinate, expanding in angular Fourier series, and using Mellin transforms to deconvolve the Gaussian kernel, yielding explicit inversion formulas.
Significance. If the stated inversion formulas are valid, this is a useful and nontrivial extension of scalar Gaussian-beam Radon inversion to tensor fields, with potential applications to optical tomography of vectorial and tensor quantities. The derivation is parameter-free, the angular algebra in Theorems 1 and 3 is checked in detail, and the paper is explicit about the kernel's structure. However, the central deconvolution step repeatedly divides by Mellin transforms of the kernel coefficient g_n and by determinants of 2x2 systems, and no proof that these quantities are nonzero is provided. Since g_n(t) is oscillatory (e.g., proportional to J_n(1/t) for zero beam width), zeros are a real possibility, so the recovery formulas are not established as written. The paper also applies Mellin inversion to quantities whose convergence and meromorphy are not justified in the required half-plane. These are load-bearing gaps, but they appear fixable by adding analyticity and nonvanishing arguments or by restricting to an open dense set of parameters.
major comments (4)
- [§3.1, Eqs. (12) and (13)] The recovery of (f1)n and (f2)n divides by Ng_n(ρ−2) on both sides. The paper never proves that Ng_n(ρ−2) is nonzero on the vertical line used for the inverse Mellin transform (8). Since g_n(t) is oscillatory—for A=0, g_n(t) = (−i)^n J_n(1/t)—its Mellin transform can have zeros, so the pointwise division is not justified. An isolated zero would make the formula invalid as written, and an open set of zeros would destroy the recovery step entirely. The same issue affects Eqs. (19), (22), and (25) in Theorem 3.
- [§3.2, Eq. (17)] The reconstruction in Theorem 2 solves a 2x2 linear system in the Mellin domain and then divides by the determinant N g_{n−2}(ρ−2) N(g_{n−1}−g_{n+1})(ρ−3) − N g_n(ρ−2) N(g_{n−3}−g_{n−1})(ρ−3). No argument is given that this determinant is nonzero on the inversion line, nor that the individual Mellin factors are all nonzero. Similar unproved determinants appear in Eqs. (33)–(34) for Theorem 4, which are essential to recovering N(f22−f11+2if12)_{n−2} and N(f22−f11−2if12)_{n+2}.
- [§3.1–§3.4, Eq. (8) and surrounding text] The inverse Mellin formula (8) is quoted for functions in C_c^∞(D), but the paper applies it to Mellin transforms of products involving the Fourier-transformed data, the exponential factor exp(w0^2 σ^2/4), and kernel coefficients g_n(σ/r). The convergence of the Mellin transform, the existence of a common half-plane of holomorphy, and the integrability of the data side on the inversion line are not established. Moreover, when division by Ng_n(ρ−2) is performed, any zeros of Ng_n create poles; without a removable-singularity or meromorphic-continuation argument, the inverse Mellin integral is not even well defined.
- [§3.3, Eq. (24)] Equation (24) contains a sign/index inconsistency: the text says it computes the (n−2)-th Fourier coefficient, but the displayed integral contains e^{-i(n+2)θ}, and the left side is written as (cLf−cTf−2i dMf)_{n−2}. This makes Eq. (25) suspect as written. The error appears localized, but because Eq. (25) is later combined with Eqs. (19) and (22) in the reconstruction, it must be corrected and the subsequent formulas re-checked.
minor comments (4)
- [Throughout] The manuscript has numerous typographical and formatting issues: 'R 2', 'θ θθ', 'fourier' with lowercase, and inconsistent use of bold and non-bold symbols. These should be cleaned up for publication.
- [§3.1, Eq. (11)] After the convolution notation, the equation 'r^2{(f1)n(r) + i(f2)n(r)}×g_n(σ)' is ambiguous; the convolution variable and the constant factors should be displayed more clearly to avoid confusion about where the Mellin transform is applied.
- [§3.4, Eq. (30)] In the displayed formula for d L2f_n(σ), the kernel is written as bK(σ,−rcψ) in one place and bK(σ,−rsψ) in another; check whether the second argument should be −r s_ψ consistently.
- [§3.5] The operator A is introduced via [2] but its action on symmetric 2-tensors is only partially defined in the text; the symmetry of f is used implicitly, so it would help to state explicitly that A is applied to the tensor as a whole and then symmetrized.
Circularity Check
No load-bearing circularity: the tensor-field inversions are derived by explicit Fourier/Mellin algebra from the definitions, and the cited scalar technique is a borrowed method, not a premise that forces the result.
full rationale
The claimed derivations are self-contained in the sense relevant to circularity. Theorems 1-4 do not fit parameters and do not rename known data as predictions: each proof starts from the definitions (2)-(4) with kernel (1), takes Fourier transforms in s, expands in angular Fourier series, passes to polar coordinates, and applies Mellin inversion. The unknowns N{(f1)_n ± i(f2)_n}, N{(f11+f22)_n}, etc., are expressed in terms of Mellin transforms of the measured data divided by N g_n(ρ-2) or by determinants of such factors (e.g., Sections 3.1, 3.3, and equations (17), (33)-(34)). These are inversion formulas, not restatements of the inputs. The citation [23] is a prior scalar GbRt paper by co-author Roy; the text says 'we adopted the techniques introduced by the authors in [23]', but the present proofs re-derive the needed Fourier-Mellin manipulations and do not assume Theorems 1-4 from [23]. Thus the self-citation is a methodological reference, not a load-bearing premise. The operator A in Remark 3.1 is attributed to [2], which has no author overlap with this paper, and is used only to relate Mf to -L tilde f; that relation is a symmetry calculation, not an import of the conclusion. The genuine weaknesses here are correctness gaps rather than circularity: the paper never proves N g_n(ρ-2) is nonvanishing in the Mellin-inversion strip, nor that the 2x2 determinants in (17) and (33)-(34) are nonzero, and equation (24) contains an apparent sign/index slip. Those omissions make the pointwise division formulas conditional, but they do not make any output equal to an input by construction. Accordingly, no circular step can be exhibited, and the appropriate score is 0.
Assumptions & free parameters
assumptions (4)
- domain assumption The Gaussian kernel model (1) and the beam waist formula w(u) = w0 sqrt(1+(u/z_R)^2) accurately represent the imaging physics.
- ad hoc to paper The Mellin transform N g_n(ρ-2) is nonzero on the inversion line, and the linear systems in equations (17) and (33)-(34) have nonzero determinants.
- standard math The inverse Mellin formula (8) applies to the reconstructed Fourier coefficients.
- standard math Interchange of Fourier, Fourier series, and Mellin integrals is valid for compactly supported smooth tensor fields.
Cite this review
Pith. "Pith review of Gaussian beam Radon transform for tensor fields in $\mathbb{R}^2$." pith.science (2026). https://pith.science/paper/ASHW7LLG
@misc{pith2026260821966,
author = {Pith},
title = {Pith review of: Gaussian beam Radon transform for tensor fields in $\mathbbR^2$},
year = {2026},
howpublished = {\url{https://pith.science/paper/ASHW7LLG}},
note = {Machine review of arXiv:2608.21966}
}
abstract
In this article, we introduce and study a set of generalized Gaussian beam Radon transforms (GbRt) acting on tensor fields in $\mathbb{R}^2$. The operators considered include longitudinal, transverse, mixed GbRts, along with their integral moments. These operators extend the corresponding notions of the classical generalized Radon transforms for tensor fields. We establish reconstruction results for vector and symmetric 2-tensor fields using appropriate combinations of the defined transforms. This work extends a recent study on the recovery of scalar functions from their GbRt to the recovery of vector and tensor fields from analogously defined generalized GbRts.
Reference graph
Works this paper leans on
-
[23]
Souvik Roy, Gihyeon Jeon, and Sunghwan Moon. Radon transform with gaussian beam: Theoretical and numerical reconstruction scheme.Applied Mathematics and Computation, 452:128024, 2023
work page 2023
-
[1]
Anuj Abhishek, Rohit Kumar Mishra, and Chandni Thakkar. Generalized Radon transforms over symmetric m-tensor fields inR n.Analysis and Mathematical Physics, 16:11, 2026
work page 2026
-
[2]
Maarten de Hoop, Teemu Saksala, Gunther Uhlmann, and Jian Zhai. Generic uniqueness and stability for the mixed ray transform.Transactions of the American Mathematical Society, 374(9):6085–6144, 2021
work page 2021
-
[3]
Alexander Denisjuk. Inversion of the x-ray transform for 3D symmetric tensor fields with sources on a curve.Inverse Problems, 22(2):399, 2006
work page 2006
-
[4]
Evgeny Yu. Derevtsov and Ivan E. Svetov. Tomography of tensor fields in the plane.Eurasian Journal of Mathematical and Computer Applications, 3(2):24–68, 2015. 15
work page 2015
- [5]
-
[6]
Olli Koskela, Toni Montonen, Birhanu Belay, Edite Figueiras, Sampsa Pursiainen, and Jari Hyttinen. Gaussian light model in brightfield optical projection tomography.Scientific reports, 9(1):13934, 2019
work page 2019
-
[7]
Krishnan, Ramesh Manna, Suman K
Venkateswaran P. Krishnan, Ramesh Manna, Suman K. Sahoo, and Vladimir A. Sharafutdinov. Momentum ray transforms.Inverse Problems & Imaging, 13(3):679–701, 2019
work page 2019
Show all 31 references
-
[8]
Krishnan, Ramesh Manna, Suman K
Venkateswaran P. Krishnan, Ramesh Manna, Suman K. Sahoo, and Vladimir A. Sharafutdinov. Momentum ray transforms, II: range characterization in the Schwartz space.Inverse Problems, 36(4):045009, 2020
2020
-
[9]
Krishnan, Rohit K
Venkateswaran P. Krishnan, Rohit K. Mishra, and Fran¸ cois Monard. On solenoidal-injective and injective ray transforms of tensor fields on surfaces.Journal of Inverse and Ill-posed Problems, 27(4):527–538, 2019
2019
-
[10]
Weighted radon transforms of vector fields, with applications to magnetoacoustoelectric tomography.Inverse Problems, 39(6):065014, 2023
Leonid Kunyansky, Eric McDugald, and Benjamin Shearer. Weighted radon transforms of vector fields, with applications to magnetoacoustoelectric tomography.Inverse Problems, 39(6):065014, 2023
2023
-
[11]
Mathematics of vectorial gaussian beams
Uri Levy, Yaron Silberberg, and Nir Davidson. Mathematics of vectorial gaussian beams. Advances in Optics and Photonics, 11(4):828–892, 2019
2019
-
[12]
Alfred K. Louis. A unified approach to inversion formulae for vector and tensor ray and radon transforms and the natterer inequality.Inverse Problems, 40(8):085007, 2024
2024
-
[13]
Rohit K. Mishra. Full reconstruction of a vector field from restricted Doppler and first integral moment transforms inR n.Journal of Inverse and Ill-posed Problems, 28(2):173–184, 2020
2020
-
[14]
Mishra and Suman K
Rohit K. Mishra and Suman K. Sahoo. Injectivity and range description of integral moment transforms overm-tensor fields inR n.SIAM Journal on Mathematical Analysis, 53(1):253–278, 2021
2021
-
[15]
Mishra and Suman K
Rohit K. Mishra and Suman K. Sahoo. The generalized Saint Venant operator and integral moment transforms.Proc. Amer. Math. Soc., 151(1):189–199, 2023
2023
-
[16]
Radon transform over tensor fields: Injectivity, range, and unique continuation principle.arXiv preprint arXiv:2603.27638, 2026
Rohit Kumar Mishra and Chandni Thakkar. Radon transform over tensor fields: Injectivity, range, and unique continuation principle.arXiv preprint arXiv:2603.27638, 2026
2026
-
[17]
SIAM, 2001
Frank Natterer.The Mathematics of Computerized Tomography. SIAM, 2001
2001
-
[18]
Gourdon P
X. Gourdon P. Flajolet and P. Dumas. Mellin transforms and asymptotics: Harmonic sums. Theoretical computer science, 144(1-2):3–58, 1995
1995
-
[19]
Paternain, Mikko Salo, and Gunther Uhlmann
Gabriel P. Paternain, Mikko Salo, and Gunther Uhlmann. Tensor tomography on surfaces. Inventiones Mathematicae, 193(1):229–247, 2013
2013
-
[20]
Johann Radon. ¨Uber die bestimmung von funktionen durch ihre integralwerte l¨ angs gewisser mannigfaltigkeiten.Berichte ¨ uber die Verhandlungen der K¨ oniglich-S¨ achsischen Akademie der Wissenschaften, 1917. 16
1917
-
[21]
Inverse scattering for optical coherence tomography.Journal of the Optical Society of America A, 23(5):1027– 1037, 2006
Tyler S Ralston, Daniel L Marks, P Scott Carney, and Stephen A Boppart. Inverse scattering for optical coherence tomography.Journal of the Optical Society of America A, 23(5):1027– 1037, 2006
2006
-
[22]
Gaussian beam deconvolution in optical coherence tomography
Tyler S Ralston, Daniel L Marks, Farzad Kamalabadi, and Stephen A Boppart. Gaussian beam deconvolution in optical coherence tomography. InThree-Dimensional and Multidimensional Microscopy: Image Acquisition and Processing XII, volume 5701, pages 1–12. SPIE, 2005
2005
-
[24]
On theX-ray transform of planar symmetric 2-tensors.J
Kamran Sadiq, Otmar Scherzer, and Alexandru Tamasan. On theX-ray transform of planar symmetric 2-tensors.J. Math. Anal. Appl., 442(1):31–49, 2016
2016
-
[25]
Sharafutdinov.Integral Geometry of Tensor Fields
Vladimir A. Sharafutdinov.Integral Geometry of Tensor Fields. VSP, 1994
1994
-
[26]
Siegman.Lasers
Anthony E. Siegman.Lasers. University Science Books, Mill Valley, CA, 1986
1986
-
[27]
Svetov and Anna P
Ivan E. Svetov and Anna P. Polyakova. Reconstruction of three-dimensional vector fields based on values of normal, longitudinal, and weighted radon transforms.Journal of Applied and Industrial Mathematics, 17(4):842–858, 2023
2023
-
[28]
Svetov and Anna P
Ivan E. Svetov and Anna P. Polyakova. Inversion of generalized radon transforms acting on 3d vector and symmetric tensor fields.Inverse Problems, 40(1):015009, 2024
2024
-
[29]
Titchmarsh.Introduction to the Theory of Fourier Integrals
Edward C. Titchmarsh.Introduction to the Theory of Fourier Integrals. Clarendon Press, Oxford, 1937
1937
-
[30]
Point spread function based image reconstruction in optical projection tomography.Physics in Medicine & Biology, 62(19):7784–7797, 2017
Anna K Trull, Jelle Van Der Horst, Willem Jan Palenstijn, Lucas J Van Vliet, Tristan Van Leeuwen, and Jeroen Kalkman. Point spread function based image reconstruction in optical projection tomography.Physics in Medicine & Biology, 62(19):7784–7797, 2017
2017
-
[31]
Comparison of image reconstruction techniques for optical projection tomography.Applied Optics, 57(8):1874– 1882, 2018
Anna K Trull, Jelle van der Horst, Lucas J Van Vliet, and Jeroen Kalkman. Comparison of image reconstruction techniques for optical projection tomography.Applied Optics, 57(8):1874– 1882, 2018. 17
2018
Reviewed August 27, 2026 · model on record in the stance chip above.
Discussion (0). Continue with ORCID to comment.