{"id":"d7a8b025-a04e-460b-bbd7-55a93d81f5e9","arxiv_id":"2608.01493","paper_version":1,"verdict":"CONDITIONAL","confidence":"HIGH","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":0,"one_line_summary":"MiraSOL's DMD-based prototype demonstrates full-disk solar imaging and dynamic spatial masking, and reveals a 60 Hz flicker from the evaluation board electronics.","lead":"This paper introduces MiraSOL, an instrument that uses a digital micromirror device to select specific solar features for high-resolution spectroscopy. A proof-of-concept prototype imaged the full solar disk and dynamically masked a pattern, demonstrating that the concept works.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The unvalidated linchpin is the ON-state science path: DMD-to-integrating-sphere-to-fiber coupling is untested, and the prototype only demonstrates OFF-state imaging, so the spectrograph function required by the science case remains unsupported.","rationale":"The reader's weakest_assumption correctly identifies the missing link: ON-state coupling into the integrating sphere/fiber is assumed but untested. The paper's own text admits the coupling optics are under optimization and that spectrographic performance has not been tested on-sky. The prototype's imaging arm uses the OFF-state channel, so the images, while compelling, do not exercise the science channel. The central claim of the paper is carefully phrased as validation of 'the core concept of using a DMD for solar spatial modulation,' which is supported. However, the title and abstract describe a DMD-based spectrograph, and the science requirements trace to high-resolution spectra of selected regions; without the ON-state coupling demonstration, the instrument's main purpose remains unproven. I do not see an internal inconsistency or a reason to reject the paper; it is an honest preliminary design/proof-of-concept, and the missing demonstration is exactly what a CONDITIONAL verdict should require. The 60 Hz flicker is a secondary concern because it might affect the science channel, but it does not undermine the spatial-modulation feasibility. Thus the reader's CONDITIONAL verdict remains appropriate, and no adjustment is needed.","tokens_in":10765,"tokens_out":3107,"duration_ms":41803,"concrete_test":"Assemble the Sec. 4 spectrometer channel: ON-state beam into the integrating sphere, then into a fiber identical in diameter/NA to those used by NEID or HPF. With the DMD set all-ON, measure the optical power at the fiber output relative to the deployable-fold-mirror bypass path (disk-integrated) at 500–900 nm. Also record the time series at 10 kHz to quantify any 60/120 Hz modulation in the coupled light. If the coupled throughput is below the level needed to reach SNR>300 at R>100,000 in a 1-minute exposure, or if flicker-induced power variations exceed the 50 cm/s RV budget after integrating, the core spectrograph concept is not validated.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The paper's central feasibility claim is that the prototype 'validates the core concept of using a DMD for solar spatial modulation.' That is true for spatial masking, but the instrument's name and science goals require a spectrograph channel. In Sec. 4, the ON-state beam is directed to an integrating sphere whose 'imaging optics (currently under optimization)' will feed a spectrograph; in Sec. 5, the authors explicitly note that 'the spectrographic performance of this specific DMD model has yet to be tested on-sky.' The prototype images are taken through the OFF-state imaging channel only; the dark 'PSU' pattern confirms that ON-state light is being redirected away from the camera, but nothing demonstrates that this redirected light can be efficiently coupled into a fiber and delivered to a spectrograph. If the ON-state beam has poor etendue matching, low throughput, or modal instability when injected into a small-core fiber, the EPRV surface-mapping and transit-simulation goals fail regardless of how well the DMD can image the Sun. The 60 Hz flicker is a related but secondary risk: it was measured in the all-ON state, so it directly affects the science channel, but its attribution to the TI evaluation board is a hypothesis. Thus the load-bearing unvalidated assumption is the efficiency and stability of the ON-state coupling path, not DMD imaging or masking.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"This proceedings paper presents the science motivation, preliminary design requirements, laboratory characterization, and a first prototype for MiraSOL, a proposed solar feed that uses a DLP801RE digital micromirror device (DMD) for spatially resolved spectroscopy and synthetic transit simulation. The authors report a 60 Hz optical flicker (appearing as two phase-offset 60 Hz signals, i.e., a 120 Hz pattern) in the DMD when driven by a TI evaluation board, which they hypothesize is an automated micromirror reset sequence. They also simulate the efficiency gain of a hypothetical NIR-coated window. The prototype, built from COTS components, images the full solar disk onto the DMD and demonstrates dynamic spatial masking by darkening a pattern ('PSU') in the imaging channel. No spectrograph-channel data are presented; the integrating-sphere coupling optics are explicitly stated to be under optimization, and the spectrographic performance is acknowledged as untested on sky.","tokens_in":11110,"tokens_out":7183,"duration_ms":81437,"significance":"If the full instrument is realized, MiraSOL would provide a unique capability for spatially resolved solar spectroscopy and controllable synthetic transits, directly addressing stellar-variability limits in EPRV and the transit light source effect. The prototype does validate the core DMD-based spatial-modulation concept: full-disk solar imaging with pixel-level control is clearly shown. The lab detection of the 60 Hz flicker is a useful practical characterization for anyone repurposing HEP DMDs. The paper's explicit acknowledgment of the untested ON-state science path is a strength; the claims are mostly scoped to spatial modulation. The main weakness is that the fiber-fed spectrograph channel—central to the instrument's stated science goals—remains entirely unvalidated, and the flicker amplitude is not quantified. For a preliminary proceedings paper, this is acceptable if the framing is carefully limited.","major_comments":[{"comment":"The amplitude of the 60 Hz flicker is not quantified. The y-axis is 'Fractional Current' with no absolute scale or stated peak-to-peak modulation. Since this flicker affects the ON-state science path and the paper presents it as a key discovery, please report the modulation depth (e.g., percent), the DC level, and ideally a power spectrum or a comparison with the direct-light bypass path to confirm it is not a setup artifact.","section":"Sec. 3, Fig. 3"},{"comment":"The ON-state science path is not tested. Sec. 4 states the spectrometer-channel imaging optics are 'currently under optimization', and Sec. 5 confirms only the imaging channel was populated on sky. Thus the feasibility of efficiently coupling the ON-state beam into an integrating sphere and fiber-fed EPRV spectrograph—a core requirement for the stated science goals—remains unvalidated. Please either add a laboratory throughput/stability measurement of this path or explicitly limit the paper's central claim to spatial modulation, with a prominent statement that the spectrograph function is a future design goal, not a demonstrated capability.","section":"Sec. 4 / Sec. 5"},{"comment":"The horizontal banding in Fig. 7 is attributed to the 60 Hz reset sequence, but the text says 'likely' and proposes a future test. Because banding could also arise from camera readout or other electronics, please provide direct evidence for this attribution (e.g., images at exposure times that are integer multiples or half-integers of the 60 Hz period, or a time series of a static DMD state) or clearly separate the banding observation from the lab flicker measurement.","section":"Sec. 5, Fig. 7"}],"minor_comments":[{"comment":"Typo: 'an new experimental platform' should be 'a new experimental platform'.","section":"Abstract"},{"comment":"Heading 'T ransmission' contains an unintended space; should be 'Transmission'.","section":"Sec. 2.2"},{"comment":"Clarify that the NIR-coating curve is a hypothetical configuration and state the assumed window transmission values; the current simulation depends on an unstated coating model.","section":"Sec. 3, Fig. 4"},{"comment":"The abbreviation 'EPR V' with a space appears in several places; use 'EPRV' consistently.","section":"Sec. 2.1"},{"comment":"The term 'pond of mirrors' is introduced without a definition; a brief parenthetical explanation would help readers unfamiliar with DMD terminology.","section":"Sec. 2.3"}],"recommendation":"minor_revision","confidential_remarks":"The reader's circularity concern does not land: the self-citation to Robles & Mahadevan (2026) is an external input, not a circular derivation. The paper is honest about the untested spectrograph channel, and for a SPIE-style proceedings the current evidence supports a limited feasibility claim. The major comments ask for a quantified flicker characterization and either a simple ON-path test or a clearer scope limitation; these are addressable within the manuscript's scope and do not require rejection."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Read this as a workshop-style instrument paper, not a full system demonstration. The real new content is the prototype: a COTS DLP801RE DMD imaging the full solar disk with ~3 arcsec sampling per micromirror, plus dynamic masking that actually works—the PSU pattern is convincing. The other genuinely new piece is the 60 Hz flicker measurement from the TI evaluation board. The phase-folded data showing two offset 60 Hz reset signals is clean and reproducible from the figure alone; anyone using HEP DMDs for precise photometry should know about it. The authors also did a thoughtful job with the science traceability matrix, the pond-of-mirrors safety buffer, and the contrast ratio requirement.\n\nThe soft spot is exactly where the stress-test note lands: the ON-state science path is unvalidated. The spectrograph channel depends on coupling the ON-state beam into an integrating sphere and then into a fiber, and the authors state the imaging optics are “currently under optimization.” No spectrographic test is presented, and the prototype only exercises the OFF-state imaging channel. If the ON-state beam has poor etendue matching, low throughput, or modal instability when launched into a small-core fiber, the surface-mapping and transit-simulation goals fail regardless of how well the DMD can image the Sun. To their credit, the authors do say on-sky spectrographic performance has yet to be tested, so they are not hiding this. The conclusion does overreach slightly: “validates the core concept” should be “validates spatial masking,” not the full XDMD-based spectrograph concept.\n\nThe flicker origin is plausibly an automated reset sequence in the TI firmware, but it is still a hypothesis. The horizontal banding in the prototype images is attributed to the same 60 Hz signal beating against short exposures; the proposed test (adding a filter to lengthen exposures) is reasonable, but the link is not yet measured. The NIR efficiency simulation depends on a hypothetical Corning NIR window coating, not a measured part. No data or code are released, which limits reproducibility for a methods-heavy paper. None of these are fatal at this stage, but they are real limits.\n\nThis paper is for instrument builders in the solar and EPRV community, especially anyone considering DMDs. I would cite it for the flicker characterization and the pixel-level full-disk masking demo. It deserves a serious referee because it reports a real prototype and a new measurement, but the review should require the conclusion to be scaled back and a clear statement of what remains to be de-risked in the ON-state path.","headline":"A solid proof-of-concept for DMD solar masking with a useful new flicker measurement, but the instrument's spectrograph channel is untested, so the paper is a pathfinder, not a validation of the full science concept.","tokens_in":11541,"tokens_out":2357,"would_cite":true,"duration_ms":31884,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":["95.55.-n"],"model":"deepseek-v4-flash","headline":"A prototype built around a digital micromirror device demonstrates pixel-level masking of the full solar disk, the core of a planned solar feed for spatially resolved extreme-precision radial-velocity spectroscopy and simulated transits.","keywords":["digital micromirror device","solar spectroscopy","extreme precision radial velocity","spatial light modulator","transit light source effect","solar variability","Sun-as-a-star","DMD flicker"],"falsifier":"Point the prototype at the Sun, command a small group of micromirrors ON, and record the fiber-coupled spectrum: if the selected region cannot be recovered at the projected signal-to-noise and radial-velocity stability, the core science case fails. A second check: replace or reprogram the evaluation board to remove the 60 Hz reset flicker and remeasure the ON/OFF contrast; if it stays near 250:1, the simulated-transit mode cannot reach the 1000 ppm sensitivity claimed.","tokens_in":10675,"feed_emoji":"☀️","tokens_out":9079,"duration_ms":84890,"temperature":0.7,"pith_summary":"MiraSOL is a proposed solar feed built around a commercial digital micromirror device (DMD): each tiny mirror can be flipped independently, so the instrument can select arbitrary regions of the solar disk for spectroscopy while an imaging channel records exactly which regions were selected. The paper's claim is that this spatial-modulation concept works — a proof-of-concept prototype imaged sunspots and carved a dynamic mask across the solar disk — and that the design can feed an extreme-precision radial-velocity spectrograph to map stellar variability or simulate planetary transits. The paper also reports a newly identified 60 Hz optical flicker introduced by the commercial evaluation electronics, an artifact that must be dealt with before precision spectroscopy.","feed_headline":"A DMD prototype carves patterns across the solar disk","feed_subtitle":"Each switchable mirror samples 3 arcseconds of the Sun, enabling resolved stellar-variability spectra and simulated transits.","key_machinery":"The central object is the DLP801RE digital micromirror device used as a spatial light modulator. Each micromirror toggles between an ON state, which sends light into an integrating sphere and then a fiber-fed spectrograph, and an OFF state, which sends light to an imaging camera; because the same mask defines both channels, the image shows the exact spatial origin of each spectrum. Supporting mechanisms include the 3-arcsecond-per-mirror sampling, the requirement that a simulated planet span at least a $3\\times3$ mirror region, and the 'pond of mirrors' buffer zone that keeps stray light from the inactive area out of the science beam.","core_discovery":"On its own terms, the paper establishes that a high-efficiency-pixel DMD can be used as a dynamic spatial mask for the full solar disk at 3 arcsecond sampling per micromirror. The prototype, built from commercial off-the-shelf optics, produced images in which sunspots are visible and in which a commanded three-letter pattern removes light from a chosen region, demonstrating pixel-level control of the solar image. In parallel, high-speed photometry of the DMD in an all-ON state revealed a 60 Hz flicker — two phase-offset 60 Hz trains that appear as 120 Hz — attributed to an automated micromirror reset sequence in the evaluation firmware. The paper presents this as validation of the core conce","pith_inferences":["If the flicker is indeed an anti-stiction reset routine in the evaluation firmware, a scientific-grade DMD controller or exposure synchronization to the reset phase should remove it; that is a direct test the paper does not run.","The same spatial-mask capability could map convective blueshift limb-to-limb by occulting concentric annuli, giving a center-to-limb curve without needing eclipse events.","If removing the flicker raises the contrast well above 250:1, simulated transits could reach below 1000 ppm and approach the roughly 200 ppm oblateness signature the paper cites, making the prototype a testbed for transit models used by space-based observatories.","A direct next step, implied but not built, is swapping the visible-coated window for an NIR-coated one; the paper's efficiency simulation indicates this would make the same DMD competitive for near-infrared spectrographs."],"forward_implications":["MiraSOL would let observers isolate sunspots, plage, and other active regions for high-resolution spectra, directly probing how magnetic activity suppresses convective blueshift.","By rapidly switching mirrors OFF along a moving chord, it can synthesize transits of known size and shape — including oblate planets — providing ground truth for the transit light source effect and for oblateness models.","The dual-channel design gives real-time verification of where each spectrum came from, since masked regions appear dark in the imaging arm.","A deployable fold mirror lets the same instrument run as a conventional full-disk Sun-as-a-star feed when spatial modulation is not needed.","The 60 Hz evaluation-board flicker, if uncorrected, limits contrast and imprints banding on short exposures, so a scientific controller or timing solution is a prerequisite for the extreme-precision radial-velocity and transit-depth goals."],"supporting_citations":[{"why":"Supplies the earlier contrast measurement and efficiency simulation for the HEP DMD that the flicker study and expected spectrographic performance build on.","marker":"[30]"},{"why":"Documents the HEP DMD pixel design and explains why the DLP801RE was selected over other DMD models.","marker":"[29]"},{"why":"Describes an earlier DMD-based astronomical spectrograph (SAMOS), providing the design precedent MiraSOL extends.","marker":"[28]"},{"why":"Describes the NEID solar feed whose housing and operational model set MiraSOL's daily-observation and tracking requirements.","marker":"[23]"},{"why":"Provides the parameter-free Rossiter-McLaughlin eclipse curve that motivates resolving the solar surface to probe convective blueshift.","marker":"[13]"},{"why":"Defines the transit light source effect that the simulated-transit mode is designed to test.","marker":"[16]"},{"why":"Sets the 50 cm/s stability, R>100,000, and SNR>300 instrument requirements adopted for the extreme-precision radial-velocity science channel.","marker":"[5]"},{"why":"Makes the case that high-quality plage spectra are missing from stellar variability models, driving the surface-mapping mode.","marker":"[14, 15]"}],"fun_headline_variants":["Solar disk becomes a canvas for DMD spectroscopy","Dynamic DMD masks reveal sun and simulate exoplanet transits","Digital micromirrors slice the solar disk for spectroscopy","MiraSOL: pixel-level solar masks for stellar variability","DMD maps the Sun at 3-arcsecond resolution"],"cache_read_input_tokens":2816,"weakest_assumption_plain":"The ON-state light reflected by selected micromirrors can be coupled through an integrating sphere into a fiber-fed spectrograph with acceptable throughput and stability; those optics are still under optimization and no spectrographic measurement is presented.","fun_headline_variants_meta":{"raw":{"variants":["Solar disk becomes a canvas for DMD spectroscopy","Dynamic DMD masks reveal sun and simulate exoplanet transits","Digital micromirrors slice the solar disk for spectroscopy","MiraSOL: pixel-level solar masks for stellar variability","DMD maps the Sun at 3-arcsecond resolution"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000722,"raw_usage":{"total_tokens":3087,"prompt_tokens":763,"completion_tokens":2324,"prompt_tokens_details":{"cached_tokens":256},"prompt_cache_hit_tokens":256,"prompt_cache_miss_tokens":507,"completion_tokens_details":{"reasoning_tokens":2257}},"tokens_in":507,"tokens_out":2324,"duration_ms":16253,"temperature":1.0,"reasoning_tokens":2257,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-06T00:04:38.096659+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Point the prototype at the Sun, command a small group of micromirrors ON, and record the fiber-coupled spectrum: if the selected region cannot be recovered at the projected signal-to-noise and radial-velocity stability, the core science case fails. A second check: replace or reprogram the evaluation board to remove the 60 Hz reset flicker and remeasure the ON/OFF contrast; if it stays near 250:1, the simulated-transit mode cannot reach the 1000 ppm sensitivity claimed.","supporting_citations":[{"cited_title":"HEP digital micromirror devices for precision solar spectroscopy","cited_arxiv_id":"2601.23176","evidence_quote":"Supplies the earlier contrast measurement and efficiency simulation for the HEP DMD that the flicker study and expected spectrographic performance build on."},{"cited_title":"The HEP DMD: a new DLP pixel optimized for performance,","cited_arxiv_id":null,"evidence_quote":"Documents the HEP DMD pixel design and explains why the DLP801RE was selected over other DMD models."},{"cited_title":"The opto-mechanical design of SAMOS: a DMD-based spectrograph for the SOAR telescope,","cited_arxiv_id":null,"evidence_quote":"Describes an earlier DMD-based astronomical spectrograph (SAMOS), providing the design precedent MiraSOL extends."},{"cited_title":"Observing the sun as a star: Design and early results from the neid solar feed,","cited_arxiv_id":null,"evidence_quote":"Describes the NEID solar feed whose housing and operational model set MiraSOL's daily-observation and tracking requirements."},{"cited_title":"Radial velocity observations of the 2015 Mar. 20 eclipse. A benchmark Rossiter-McLaughlin curve with zero free parameters,","cited_arxiv_id":null,"evidence_quote":"Provides the parameter-free Rossiter-McLaughlin eclipse curve that motivates resolving the solar surface to probe convective blueshift."},{"cited_title":"The Transit Light Source Effect. II. The Impact of Stellar Heterogeneity on Transmission Spectra of Planets Orbiting Broadly Sun-like Stars,","cited_arxiv_id":null,"evidence_quote":"Defines the transit light source effect that the simulated-transit mode is designed to test."}],"review_version":1}