{"id":"28ab7f08-fc9e-4489-a684-e1abd3f24525","arxiv_id":"2508.00237","paper_version":1,"verdict":"UNVERDICTED","confidence":"LOW","novelty_score":7.0,"correctness_risk":"unknown","formal_verification":"none","parameter_count":0,"one_line_summary":"Secondary polarization in coronagraphs is coherent with but orthogonal to the input field, so dark hole optimization that suppresses primary polarization also suppresses secondary intensity.","lead":"This paper analyzes how stellar coronagraphs introduce a small amount of instrument polarization, called secondary polarization. It argues that this secondary polarization is coherent with the input light but does not interfere with it, and that optimizing the dark hole for the primary polarization also suppresses this secondary light, which could relax design requirements.","discovery_kind":"first_principles","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The abstract's key consequence—primary dark hole also suppresses secondary intensity—does not follow from coherence and orthogonality alone; it requires a pupil-plane Jones matrix with constant cross-to-co-polarization ratio, which dielectric surfaces generally violate.","rationale":"The reader identified the model fidelity as the weakest assumption, which is external to the paper's internal logic. My concern is internal: even granting the Jones calculus and vector field simulations, the abstract's 'key consequence' is not a logical corollary of coherence and orthogonality. It requires an additional structural condition on the spatial variation of the Jones matrix. This is more load-bearing because it threatens the central practical conclusion (relaxed polarization requirements) within the paper's own model, not just in the presence of unmodeled effects. However, since only the abstract was available, I cannot determine whether the full text proves the required proportionality or demonstrates it numerically. The reader's UNVERDICTED verdict is therefore appropriate; my concern reinforces that the verdict cannot be upgraded without seeing the derivation. The suggested concrete test provides a way to settle the concern once the full derivation is available.","tokens_in":699,"tokens_out":6413,"duration_ms":69042,"concrete_test":"From the paper's Jones calculus, derive the pupil-plane ratio R(u) = J_sp(u)/J_pp(u) across the aperture. If R(u) is not constant, compute the focal-plane secondary-to-primary amplitude ratio r(x) = S[φ0](x)/P[φ0](x) for the unoptimized field. Then re-run the dark-hole optimization with the full vector model and measure the secondary intensity inside the optimized primary dark hole. If the secondary contrast remains above the target (e.g., > 1e-9) while the primary is at 1e-10, the mitigation claim fails for that architecture. For a direct analytical check, derive the condition under which P[φ] = 0 implies S[φ] = 0 for arbitrary φ; if the only solutions require J_sp proportional to J_pp, the abstract's general claim is overbroad.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central inference is the step from 'secondary polarization is coherent with the input but orthogonal' to 'creating a dark hole in the primary polarization also mitigates the secondary intensity.' Coherence and orthogonality only imply that total intensity is |E_p|^2 + |E_s|^2 with no cross term; they say nothing about the spatial structure of E_s. After a common-path scalar phase from the deformable mirror, the focal-plane fields are E_p = P[φ] and E_s = S[φ], where P and S are different linear operators whenever the pupil-plane Jones matrix has a spatially varying ratio J_sp/J_pp. Dielectric surfaces introduce angle-dependent Fresnel coefficients, so this ratio is typically not constant. In that case, a phase command that nulls P need not null S, and the secondary intensity in the dark hole can remain at a level set by |S[φ]|^2. The abstract presents the mitigation as a 'key consequence' without stating the needed condition (e.g., J_sp proportional to J_pp across the pupil). Unless that condition is derived and shown to hold for the modeled coronagraph, the central claim is an untested assumption rather than a demonstrated consequence.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper argues, on the basis of Jones calculus and vector field simulations that include dielectric surface interactions, that the instrumental polarization introduced by stellar coronagraphs is fully coherent with the input field but, being orthogonal to it, does not interfere with it. The central claim is that a dark hole created in the primary polarization will also substantially reduce the secondary intensity in the dark hole region, which could relax polarization design requirements and has consequences for modulation schemes.","tokens_in":944,"tokens_out":2574,"duration_ms":27723,"significance":"If the central claim is correct, it would have a practical impact on coronagraph design by potentially relaxing polarization tolerances. The paper also contributes a more rigorous treatment of the term 'incoherent' applied to instrumental polarization. Strengths of the approach as described are its use of a coherent-based analysis and vector simulations rather than a simple scalar approximation. However, the significance is currently contingent on an unstated condition connecting the spatial structure of the primary and secondary focal-plane fields; without that condition, the key mitigation claim is not established.","major_comments":[{"comment":"The abstract's key consequence does not follow from coherence and orthogonality alone. In a pupil-plane Jones formalism, the focal-plane fields can be written as E_p = P[φ] and E_s = S[φ], where P and S are different linear operators whenever the pupil-plane Jones ratio J_sp/J_pp varies spatially. Coherence and orthogonality only eliminate the cross term in intensity; they do not constrain the focal-plane structure of E_s. Thus, a phase command that nulls P need not null S unless S is proportional to P, that is, unless J_sp = c J_pp for a constant c across the pupil. The abstract does not state or derive this condition. Dielectric surfaces generally produce angle-dependent Fresnel coefficients, so this condition is not guaranteed. The authors should state the required condition explicitly, derive it or show numerically that it holds for their modeled coronagraph, and quantify the amount of secondary-intensity suppression that follows.","section":"Abstract"},{"comment":"The phrase 'tends to also significantly mitigate' is too vague to support the practical conclusion that polarization requirements can be relaxed. The paper needs to provide quantitative simulation results, for representative contrast goals and polarization leakage levels, showing the reduction factor of the secondary intensity in the dark hole region. Without such numbers, the claim is not testable.","section":"Abstract"},{"comment":"The abstract states that the simulations include 'interactions with dielectric surfaces' but gives no description of the model fidelity. The central result depends on the assumption that the Jones calculus plus the surface interaction model captures the full vector state of light, and that no additional effects such as stress birefringence, coating nonuniformities, or wavefront-dependent polarization mixing break the orthogonality or the proportionality condition. These modeling assumptions and their limitations should be stated explicitly, with discussion of how the results would change if those effects are present.","section":"Abstract"}],"minor_comments":[{"comment":"There is a quotation-mark mismatch in 'often referred to as ``incoherent,' where the closing quotation mark is missing.","section":"Abstract"},{"comment":"The phrase 'coherence secondary polarization' in the second sentence is grammatically awkward; consider reformulating to 'the coherence of the secondary polarization'.","section":"Abstract"},{"comment":"The term 'fully coherent' is used without definition. Since orthogonality prevents interference, it would help to define the coherence measure used and state what observable consequence the coherence property has beyond intensity additivity.","section":"Abstract"}],"recommendation":"major_revision","confidential_remarks":"This review is based only on the abstract because the full text was not available. The main technical concern — that the mitigation claim requires a proportionality condition on the pupil-Jones matrix — is a standard caveat in polarization modeling and is likely addressable in a revision. The authors should be asked to present the derivation or counterexample explicitly. The manuscript topic fits astro-ph.IM and the journal's scope."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Both the reader and the stress-test note are working from the abstract only, and my take lines up with that. The paper's conceptual move is genuinely useful: it challenges the sloppy 'incoherent' label for instrumental polarization and replaces it with a coherent-but-orthogonal description. That distinction matters for modulation schemes and for how people model residual light. Credit where due: the abstract is honest about the 'tends to' in the dark-hole claim, and the plan to use Jones calculus plus vector simulations of dielectric surfaces is the right way to test it.\n\nThe soft spot is the inference. Coherence plus orthogonality tells you there is no cross term in intensity; it does not tell you that a phase command that nulls E_p also nulls E_s. That requires something like a constant ratio J_sp/J_pp across the pupil, and dielectric surfaces generally don't give you that. The abstract does not state this condition, and without it the 'key consequence' is an assumption about the modeled coronagraph, not a derived theorem. The paper may well prove it in the full text—the 'tends to' suggests the authors know it is not universal—but it cannot be checked from the abstract.\n\nAlso, there are no equations, code, or data in the abstract, so soundness is unverifiable. That is normal for an abstract, but it means the claim hangs entirely on the full text.\n\nWho is this for? People working on high-contrast coronagraphy for terrestrial exoplanets, especially those doing dark-hole control and polarization budgeting. A serious referee should engage with the derivation and ask the authors to state the exact condition under which secondary-intensity mitigation holds. If the condition is restrictive, the practical claim weakens; if they can derive a general bound, it stays strong.\n\nI would accept this for peer review. The conceptual correction alone justifies a referee, and the simulation work is likely to be a useful reference even if the dark-hole claim ends up conditional. I would not cite it myself until I have seen the full derivation, but I want it in the literature so we can test it.","headline":"Abstract makes a plausible conceptual correction about coherent orthogonal secondary polarization, but the key dark-hole mitigation claim needs a stated condition and the full derivation before it can be trusted.","tokens_in":1380,"tokens_out":1822,"would_cite":false,"duration_ms":18549,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"Stellar coronagraphs' polarization leak is coherent, not incoherent, and dark holes suppress it too.","keywords":["instrumental polarization","secondary polarization","coronagraphy","dark hole","polarization coherence","Jones calculus","high-contrast imaging","exoplanet direct imaging"],"falsifier":"Build or simulate a coronagraph with a deformable mirror, create a dark hole by minimizing the primary polarization intensity in a target region, then measure the orthogonal polarization intensity in that same region with a polarizing beamsplitter and a sensitive camera. If the orthogonal intensity does not drop substantially relative to adjacent regions, the claimed mitigation is wrong. Alternatively, an interferometric measurement combining the two polarization states would directly show whether the secondary field is coherent with the input field or genuinely incoherent.","tokens_in":536,"feed_emoji":"🔭","tokens_out":4543,"duration_ms":42976,"temperature":0.7,"pith_summary":"This paper seeks to replace a loose phrase with a precise optical fact: the stray polarization that coronagraphs introduce is called incoherent, but it is actually fully coherent with the incoming light. The secondary polarization is orthogonal to the primary polarization, so the two do not interfere even though they share a phase relationship. Because of that orthogonality, the paper argues, the standard dark-hole optimization—which nulls the primary polarization in a region of the image plane—also significantly reduces the secondary intensity in that same region. If true, this would relax polarization design requirements for high-contrast exoplanet missions and would force modulation schemes that separate planets from instrumental light to account for the way the secondary intensity modulates.","feed_headline":"Coronagraph dark holes suppress stray polarization too","feed_subtitle":"The stray polarization is coherent but orthogonal, so the dark-hole loop suppresses it too.","key_machinery":"The load-bearing object is the orthogonality between the primary and secondary polarization states, expressed through the identity $|\\mathbf{E}_{\\mathrm{tot}}|^2 = |\\mathbf{E}_p|^2 + |\\mathbf{E}_s|^2$ when $\\mathbf{E}_p\\cdot\\mathbf{E}_s = 0$ in a complex vector sense. A Jones calculus description of propagation through coronagraph optics, supplemented by vector field simulations of dielectric surface reflections, is used to show that the secondary field shares the input's phase (full coherence) while remaining perpendicular to the primary state. The dark hole optimization works by minimizing the primary intensity in a target region; the orthogonality identity carries that minimization over to the secondary intensity.","core_discovery":"The paper's central claim is that the secondary polarization, defined as the small instrumentally induced polarization state that a coronagraph adds to the stellar field, is fully coherent with the input field. It does not interfere with the primary polarization because the two states are orthogonal, making the cross term vanish while the total intensity is the sum of the two orthogonal components. The paper then asserts that creating a dark hole in the primary polarization—the standard high-contrast optimization target—tends to also mitigate the secondary intensity in the dark hole region, because the optimization drives the total coherent field down. This is a first-principles result obtained with Jones calculus and vector field simulations that include interactions with dielectric surfaces.","pith_inferences":["An immediate corollary the author does not spell out is that a single wavefront-control loop acting on the total field might suffice to create the dark hole, since the orthogonality removes the usual cross-term penalty.","A targeted laboratory test would be to null one polarization in a coronagraph and measure the orthogonal leakage with a polarizing beamsplitter; a matched null would confirm the mechanism.","In any real optic, stress birefringence or coating nonuniformity will introduce a small non-orthogonal component; quantifying the resulting leaked cross-term as a function of the non-orthogonality angle would show how far the mitigation survives in practice.","The coherence result also suggests that the secondary polarization could in principle be actively nulled using the same deformable mirror that nulls the primary, rather than requiring a separate polarization compensator."],"forward_implications":["Future coronagraph designs can relax polarization tolerances, because the dark-hole loop suppresses the secondary intensity along with the primary light.","Planet-star modulation schemes must include the modulation of the secondary intensity once the secondary intensity becomes non-negligible at very high contrast.","The term 'incoherent' for instrumental polarization should be dropped in favor of 'coherent but orthogonal,' which changes how the contamination can be calibrated or subtracted.","High-contrast observations of terrestrial exoplanets may need less aggressive polarization calibration than previously assumed."],"supporting_citations":[],"fun_headline_variants":["Dark hole optimization also cleans up stray polarization","Coherent stray polarization tamed by coronagraph dark holes","Polarization noise joins dark-hole suppression for free","Dark hole loops suppress orthogonal polarization too","Secondary polarization fades inside optimized dark holes"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The conclusions rest on the assumption that the Jones calculus and vector field simulations, including interactions with dielectric surfaces, capture the full vector state of the light through the coronagraph with sufficient fidelity; if real instruments add effects such as stress birefringence, coating nonuniformities, or wavefront-dependent polarization mixing that break strict orthogonality, the predicted mitigation of the secondary intensity may not hold.","fun_headline_variants_meta":{"raw":{"variants":["Dark hole optimization also cleans up stray polarization","Coherent stray polarization tamed by coronagraph dark holes","Polarization noise joins dark-hole suppression for free","Dark hole loops suppress orthogonal polarization too","Secondary polarization fades inside optimized dark holes"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000286,"raw_usage":{"total_tokens":1646,"prompt_tokens":873,"completion_tokens":773,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":489,"completion_tokens_details":{"reasoning_tokens":703}},"tokens_in":489,"tokens_out":773,"duration_ms":7731,"temperature":1.0,"reasoning_tokens":703,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-06T10:15:40.063115+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Build or simulate a coronagraph with a deformable mirror, create a dark hole by minimizing the primary polarization intensity in a target region, then measure the orthogonal polarization intensity in that same region with a polarizing beamsplitter and a sensitive camera. If the orthogonal intensity does not drop substantially relative to adjacent regions, the claimed mitigation is wrong. Alternatively, an interferometric measurement combining the two polarization states would directly show whether the secondary field is coherent with the input field or genuinely incoherent.","supporting_citations":[],"review_version":1}