{"doi":"10.1364/ol.394829","title":"Dual-slope imaging in highly scattering media with frequency-domain near-infrared spectroscopy","abstract":"We present theoretical and experimental demonstrations of a novel, to the best of our knowledge, diffuse optical imaging method that is based on the concept of dual slopes (DS) in frequency-domain near-infrared spectroscopy. We consider a special array of sources and detectors that collects intensity ( <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"> <mml:mi>I</mml:mi> </mml:math> ) and phase ( <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"> <mml:mi>ϕ</mml:mi> </mml:math> ) data with multiple DS sets. We have recently shown that <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"> <mml:mrow class=\"MJX-TeXAtom-ORD\"> <mml:mi mathvariant=\"normal\">D</mml:mi> <mml:mi mathvariant=\"normal\">S</mml:mi> </mml:mrow> <mml:mi>ϕ</mml:mi> </mml:math> reflectance data features a deeper sensitivity with respect to <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"> <mml:mrow class=\"MJX-TeXAtom-ORD\"> <mml:mi mathvariant=\"normal\">D</mml:mi> <mml:mi mathvariant=\"normal\">S</mml:mi> </mml:mrow> <mml:mspace width=\"negativethinmathspace\"/> <mml:mi>I</mml:mi> </mml:math> reflectance data. Here, for the first time, we describe a DS imaging approach based on the Moore-Penrose inverse of the sensitivity matrix for multiple DS data sets. Using a circular 8–source/9-detector array that generates 16 DS data sets at source-detector distances in the range 20–40 mm, we show that <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"> <mml:mrow class=\"MJX-TeXAtom-ORD\"> <mml:mi mathvariant=\"normal\">D</mml:mi> <mml:mi mathvariant=\"normal\">S</mml:mi> </mml:mrow> <mml:mspace width=\"negativethinmathspace\"/> <mml:mi>I</mml:mi> </mml:math> images are more sensitive to superficial ( <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"> <mml:mrow class=\"MJX-TeXAtom-ORD\"> <mml:mo>&lt;</mml:mo> </mml:mrow> <mml:mrow class=\"MJX-TeXAtom-ORD\"> <mml:mn>5</mml:mn> </mml:mrow> <mml:mspace width=\"thickmathspace\"/> <mml:mrow class=\"MJX-TeXAtom-ORD\"> <mml:mi mathvariant=\"normal\">m</mml:mi> <mml:mi mathvariant=\"normal\">m</mml:mi> </mml:mrow> </mml:math> ) perturbations, whereas <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"> <mml:mrow class=\"MJX-TeXAtom-ORD\"> <mml:mi mathvariant=\"normal\">D</mml:mi> <mml:mi mathvariant=\"normal\">S</mml:mi> </mml:mrow> <mml:mi>ϕ</mml:mi> </mml:math> images are more sensitive to deeper ( <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"> <mml:mrow class=\"MJX-TeXAtom-ORD\"> <mml:mo>&gt;</mml:mo> </mml:mrow> <mml:mrow class=\"MJX-TeXAtom-ORD\"> <mml:mn>10</mml:mn> </mml:mrow> <mml:mspace width=\"thickmathspace\"/> <mml:mrow class=\"MJX-TeXAtom-ORD\"> <mml:mi mathvariant=\"normal\">m</mml:mi> <mml:mi mathvariant=\"normal\">m</mml:mi> </mml:mrow> </mml:math> ) perturbations in highly scattering media.","journal":"Optics Letters","year":2020,"id":78794,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":17,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9703,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2020-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":270601,"name":"Angelo Sassaroli","orcid":"0000-0003-4233-7165","position":1,"is_corresponding":false},{"id":270600,"name":"Sergio Fantini","orcid":"0000-0001-5116-525X","position":2,"is_corresponding":false},{"id":409629,"name":"Giles Blaney","orcid":"0000-0003-3419-4547","position":0,"is_corresponding":true}],"reference_count":17,"raw_metadata":null,"created_at":"2026-07-18T21:50:09.793321Z","pmid":"32796984","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}