{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,17]],"date-time":"2026-02-17T19:54:08Z","timestamp":1771358048145,"version":"3.50.1"},"reference-count":52,"publisher":"MDPI AG","issue":"24","license":[{"start":{"date-parts":[[2022,12,19]],"date-time":"2022-12-19T00:00:00Z","timestamp":1671408000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Karlsruhe School of Elementary Particle and Astroparticle Physics: Science and Technology (KSETA)"},{"name":"KIT Center Elementary Particle and Astroparticle Physics (KCETA)"},{"name":"KIT-Publication Fund of the Karlsruhe Institute of Technology"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Confocal Raman microscopic (CRM) imaging has evolved to become a key tool for spatially resolved, compositional analysis and imaging, down to the \u03bcm-scale, and nowadays one may choose between numerous commercial instruments. That notwithstanding, situations may arise which exclude the use of a commercial instrument, e.g., if the analysis involves toxic or radioactive samples\/environments; one may not wish to render an expensive instrument unusable for other uses, due to contamination. Therefore, custom-designed CRM instrumentation\u2014being adaptable to hazardous conditions and providing operational flexibility\u2014may be beneficial. Here, we describe a CRM setup, which is constructed nearly in its entirety from off-the-shelf optomechanical and optical components. The original aim was to develop a CRM suitable for the investigation of samples exposed to tritium. For increased flexibility, the CRM system incorporates optical fiber coupling to both the Raman excitation laser and the spectrometer. Lateral raster scans and axial profiling of samples are facilitated by the use of a motorized xyz-translation assembly. Besides the description of the construction and alignment of the CRM system, we also provide (i) the experimental evaluation of system performance (such as, e.g., spatial resolution) and (ii) examples of Raman raster maps and axial profiles of selected thin-film samples (such as, e.g., graphene sheets).<\/jats:p>","DOI":"10.3390\/s222410013","type":"journal-article","created":{"date-parts":[[2022,12,19]],"date-time":"2022-12-19T08:41:41Z","timestamp":1671439301000},"page":"10013","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Versatile Confocal Raman Imaging Microscope Built from Off-the-Shelf Opto-Mechanical Components"],"prefix":"10.3390","volume":"22","author":[{"given":"Deseada","family":"Diaz Barrero","sequence":"first","affiliation":[{"name":"Departamento de Qu\u00edmica F\u00edsica Aplicada, Universidad Aut\u00f3noma de Madrid, Campus de Cantoblanco, 28049 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Genrich","family":"Zeller","sequence":"additional","affiliation":[{"name":"Tritium Laboratory Karlsruhe (TLK), Institute for Astroparticle Physics (IAP), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3091-8088","authenticated-orcid":false,"given":"Magnus","family":"Schl\u00f6sser","sequence":"additional","affiliation":[{"name":"Tritium Laboratory Karlsruhe (TLK), Institute for Astroparticle Physics (IAP), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Beate","family":"Bornschein","sequence":"additional","affiliation":[{"name":"Tritium Laboratory Karlsruhe (TLK), Institute for Astroparticle Physics (IAP), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4839-7310","authenticated-orcid":false,"given":"Helmut H.","family":"Telle","sequence":"additional","affiliation":[{"name":"Departamento de Qu\u00edmica F\u00edsica Aplicada, Universidad Aut\u00f3noma de Madrid, Campus de Cantoblanco, 28049 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,12,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"337","DOI":"10.1146\/annurev-anchem-062011-143152","article-title":"Raman Imaging","volume":"5","author":"Stewart","year":"2012","journal-title":"Annu. Rev. Anal. Chem."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"379","DOI":"10.1146\/annurev-anchem-062012-092646","article-title":"Modern Raman imaging: Vibrational spectroscopy on the micrometer and nanometer scales","volume":"6","author":"Opilik","year":"2013","journal-title":"Annu. Rev. Anal. Chem."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"273","DOI":"10.1007\/s12274-008-8036-1","article-title":"Raman Spectroscopy and Imaging of Graphene","volume":"1","author":"Ni","year":"2008","journal-title":"Nano Res."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Toporski, J., Dieing, T., and Hollricher, O. (2018). Confocal Raman Microscopy, Springer International Publishing AG. [2nd ed.].","DOI":"10.1007\/978-3-319-75380-5"},{"key":"ref_5","unstructured":"Rzhevskii, A. (2021). Modern Raman Microscopy: Technique and Practice, Cambridge Scholars Publishing."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"57","DOI":"10.1016\/j.jneumeth.2014.01.003","article-title":"Design and construction of a modular low-cost epifluorescence upright microscope for neuron visualized recording and fluorescence detection","volume":"225","author":"Serrano","year":"2014","journal-title":"J. Neurosci. Methods"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Rosenegger, D.G., Tran, C.H.T., LeDue, J., Zhou, N., and Gordon, G.R. (2014). A high performance, cost-effective, open-source microscope for scanning two-photon microscopy that is modular and readily adaptable. PLoS ONE, 9.","DOI":"10.1371\/journal.pone.0110475"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Ye, X., and McCluskey, M.D. (2016). Modular scanning confocal microscope with digital image processing. PLoS ONE, 11.","DOI":"10.1371\/journal.pone.0166212"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"F49","DOI":"10.1364\/JOSAB.36.000F49","article-title":"Design and construction of a Raman microscope and characterization of plasmon-enhanced Raman scattering in graphene","volume":"36","author":"AlShehab","year":"2019","journal-title":"J. Opt. Soc. Am. B"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1755","DOI":"10.1364\/JOSAA.8.001755","article-title":"Image formation in a fiber-optical confocal scanning microscope","volume":"8","author":"Gu","year":"1991","journal-title":"J. Opt. Soc. Am. A"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"705","DOI":"10.1364\/AO.31.000705","article-title":"Single-mode fibers used as confocal microscope pinholes","volume":"31","author":"Dabbs","year":"1992","journal-title":"Appl. Opt."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"985","DOI":"10.1103\/PhysRevB.27.985","article-title":"Dielectric functions and optical parameters of Si, Ge, GaP, GaAs, GaSb, InP, InAs, and InSb from 1.5 to 6.0 eV","volume":"27","author":"Aspnes","year":"1983","journal-title":"Phys. Rev. B"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"189","DOI":"10.1002\/pip.4670030303","article-title":"Optical properties of intrinsic silicon at 300 K","volume":"3","author":"Green","year":"1995","journal-title":"Prog. Photovolt."},{"key":"ref_14","unstructured":"Deschaines, T., Hodkiewicz, J., and Henson, P. (2009). Characterization of Amorphous and Microcrystalline Silicon Using Raman Spectroscopy, Thermo Fisher Scientific. Available online: https:\/\/assets.thermofisher.com\/TFS-Assets\/CAD\/Application-Notes\/D16998~.pdf."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"8670","DOI":"10.1364\/OE.16.008670","article-title":"Simple and robust image-based autofocusing for digital microscopy","volume":"16","author":"Yazdanfar","year":"2008","journal-title":"Opt. Express"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"949","DOI":"10.1366\/12-06766","article-title":"Automated quantitative spectroscopic analysis combining background subtraction, cosmic ray removal, and peak fitting","volume":"67","author":"James","year":"2013","journal-title":"Appl. Spectrosc."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1109\/79.974727","article-title":"Spectral unmixing","volume":"19","author":"Keshava","year":"2002","journal-title":"IEEE Signal Proc. Mag."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Telle, H.H., and Ure\u00f1a, A.G. (2018). Laser Spectroscopy and Laser Imaging\u2014An Introduction, CRC Press, Taylor & Francis Group.","DOI":"10.1201\/9781315156989"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"064011","DOI":"10.1088\/2040-8986\/ac6883","article-title":"RamanLIGHT\u2014A graphical user-friendly tool for pre-processing and unmixing hyperspectral Raman spectroscopy images","volume":"24","author":"Schmidt","year":"2022","journal-title":"J. Opt."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2552","DOI":"10.1002\/jrs.6024","article-title":"Automated weak signal extraction of hyperspectral Raman imaging data by adaptive low-rank matrix approximation","volume":"51","author":"He","year":"2020","journal-title":"J. Raman Spectrosc."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"7571","DOI":"10.1039\/D0AN01244K","article-title":"Raman hyperspectral imaging with multivariate analysis for investigating enzyme immobilization","volume":"145","author":"Smith","year":"2020","journal-title":"Analyst"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1415","DOI":"10.1002\/jrs.6371","article-title":"Hyperspectral Raman imaging and multivariate statistical analysis for the reconstruction of obliterated serial numbers in polymers","volume":"53","author":"Skokan","year":"2022","journal-title":"J. Raman Spectrosc."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1822","DOI":"10.1039\/C6CS00915H","article-title":"Raman spectroscopy of graphene-based materials and its applications in related devices","volume":"47","author":"Wu","year":"2018","journal-title":"Chem. Soc. Rev."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"3223","DOI":"10.1038\/s41598-020-59851-1","article-title":"Towards standardisation of contact and contactless electrical measurements of CVD graphene at the macro-, micro- and nano-scale","volume":"10","author":"Melios","year":"2020","journal-title":"Sci. Rep."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"3406","DOI":"10.1364\/AO.22.003406","article-title":"Measurement of a Gaussian laser beam diameter through the direct inversion of knife-edge data","volume":"22","author":"Khosrofian","year":"1983","journal-title":"Appl. Opt."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"393","DOI":"10.1364\/AO.48.000393","article-title":"Measurement of Gaussian laser beam radius using the knife-edge technique: Improvement on data analysis","volume":"48","author":"Silva","year":"2009","journal-title":"Appl. Opt."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1111\/j.1365-2818.2011.03549.x","article-title":"Resolution and optical sectioning in the confocal microscope","volume":"244","author":"Wilson","year":"2011","journal-title":"J. Microsc."},{"key":"ref_28","unstructured":"Borlinghaus, R.T. (2022, December 10). Super-Resolution: On a Heuristic Point of View about the Resolution of a Light Microscope. Technological Readings, Leica Microsystems CMS GmbH, Mannheim Germany, December 2014. Available online: https:\/\/downloads.leica-microsystems.com\/Leica%20TCS%20SP8%20MP\/Dedicated%20Articles\/Super-Resolution_Technological%20Readings_Dec2014.pdf."},{"key":"ref_29","unstructured":"Borlinghaus, R.T. (2022, December 10). Pinhole Effect in Confocal Microscopes. Science Lab\u2014The Knowledge Portal of Leica Microsystems CMS GmbH, Mannheim, Germany, 26 April 2017. Available online: https:\/\/www.leica-microsystems.com\/science-lab\/pinhole-effect-in-confocal-microscopes\/."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"39891","DOI":"10.1038\/srep39891","article-title":"Method for removing spectral contaminants to improve analysis of Raman imaging data","volume":"7","author":"Zhang","year":"2017","journal-title":"Sci. Rep."},{"key":"ref_31","first-page":"2243","article-title":"Raman imaging spectroscopy: History, fundamentals and current scenario of the technique","volume":"30","author":"Mitsutake","year":"2019","journal-title":"J. Braz. Chem. Soc."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"235","DOI":"10.1038\/nnano.2013.46","article-title":"Raman spectroscopy as a versatile tool for studying the properties of graphene","volume":"8","author":"Ferrari","year":"2013","journal-title":"Nat. Nanotechnol."},{"key":"ref_33","unstructured":"Lancelot, E. (2022, December 10). Graphene Studies Using Raman Spectroscopy. Application Note\u2014Nanotechnology RA50. Horiba Jobin Yvon, Palaiseau, France. Available online: https:\/\/static.horiba.com\/fileadmin\/Horiba\/Application\/Materials\/Material_Research\/Graphene\/Graphene-studies-using_Raman_Spectroscopy.pdf."},{"key":"ref_34","unstructured":"The KATRIN collaboration, Aker, M., Altenm\u00fcller, K., Amsbaugh, J., Arenz, M., Babutzka, M., Bast, J., Bauer, S., Bechtler, H., and Beck, M. (2021). The design, construction, and commissioning of the KATRIN experiment. J. Instrum., 16, T08015."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"66","DOI":"10.1111\/jmi.12249","article-title":"A simple but precise method for quantitative measurement of the quality of the laser focus in a scanning optical microscope","volume":"259","author":"MacRae","year":"2015","journal-title":"J. Microscopy"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1009","DOI":"10.2116\/analsci.20P046","article-title":"Reliable evaluation of the lateral resolution of a confocal Raman microscope by using the tungsten-dot array certified reference material","volume":"36","author":"Itoh","year":"2020","journal-title":"Anal. Sci."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1671","DOI":"10.1002\/jrs.6187","article-title":"Graphene edge method for three-dimensional probing of Raman microscopes focal volumes","volume":"52","author":"Sacco","year":"2021","journal-title":"J. Raman Spectrosc."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"e202000227","DOI":"10.1002\/jbio.202000227","article-title":"Autofocusing technologies for whole slide imaging and automated microscopy","volume":"13","author":"Bian","year":"2020","journal-title":"J. Biophotonics"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"245A","DOI":"10.1366\/000370209789379196","article-title":"Confocal Raman microscopy: Performance, pitfalls, and best practice","volume":"63","author":"Everall","year":"2009","journal-title":"Appl. Spectrosc."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"2512","DOI":"10.1039\/c0an00371a","article-title":"Confocal Raman microscopy: Common errors and artefacts","volume":"135","author":"Everall","year":"2010","journal-title":"Analyst"},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Vallee, O., Soares, M., and Soares, M. (2010). Airy functions and applications to physics, Imperial College Press. [2nd ed.].","DOI":"10.1142\/p709"},{"key":"ref_42","unstructured":"Braat, J.J.M., Dirksen, P., van Haver, S., and Janssen, A.J.E.M. (2022, December 10). Extended Nijboer-Zernike (ENZ) Analysis and Aberration Retrieval (Last Update: 25 February 2022). Available online: https:\/\/nijboerzernike.nl\/."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"7","DOI":"10.12688\/openreseurope.13073.1","article-title":"Simple and robust method for determination of laser fluence thresholds for material modifications: An extension of Liu\u2019s approach to imperfect beams","volume":"1","author":"Grojo","year":"2021","journal-title":"Open Res. Europe"},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Hunstig, M. (2017). Piezoelectric Inertia Motors\u2014A critical review of history, concepts, design, applications, and perspectives. Actuators, 6.","DOI":"10.3390\/act6010007"},{"key":"ref_45","unstructured":"GFET-S10 for Sensing Applications (2022, December 10). Graphenea, San Sebastian, Spain. Available online: https:\/\/www.graphenea.com\/products\/gfet-s10-for-sensing-applications-10-mm-x-10-mm."},{"key":"ref_46","unstructured":"Monolayer graphene film on quartz\u2014Product Datasheet (2022, December 10). Graphenea, San Sebastian, Spain. Available online: https:\/\/cdn.shopify.com\/s\/files\/1\/0191\/2296\/files\/Graphenea_Monolayer_Graphene_on_Quartz_Datasheet_02-16-2022.pdf?v=1645025384."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"05G401","DOI":"10.1116\/1.5034433","article-title":"Review Article\u2014Hydrogenated graphene: A user\u2019s guide","volume":"36","author":"Whitener","year":"2018","journal-title":"J. Vac. Sci. Technol. A"},{"key":"ref_48","unstructured":"Fabriciu, A., Catanzaro, A., and Cultrera, A. (2022, December 10). The 16NRM01 EMPIR GRACE Consortium. Good Practice Guide on the Electrical Characterisation of Graphene Using Contact Methods. Available online: http:\/\/empir.npl.co.uk\/grace\/wp-content\/uploads\/sites\/32\/2020\/04\/20200428_GRACE_GPG_1_v1.pdf."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"793","DOI":"10.1038\/s41467-018-03026-0","article-title":"Quantum and electrochemical interplays in hydrogenated graphene","volume":"9","author":"Jiang","year":"2018","journal-title":"Nature Commun."},{"key":"ref_50","doi-asserted-by":"crossref","unstructured":"Scardaci, V., and Compagnini, G. (2021). Raman spectroscopy investigation of graphene oxide reduction by laser scribing. Carbon, 7.","DOI":"10.3390\/c7020048"},{"key":"ref_51","unstructured":"Guillemette, J. (2014). Electronic transport in hydrogenated graphene. [Ph.D. Thesis, McGill University]."},{"key":"ref_52","first-page":"1","article-title":"Multivariate data processing of spectral images: The ugly, the bad, and the true","volume":"9","author":"Lee","year":"2007","journal-title":"Spectroscopy"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/24\/10013\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T01:44:15Z","timestamp":1760147055000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/24\/10013"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,12,19]]},"references-count":52,"journal-issue":{"issue":"24","published-online":{"date-parts":[[2022,12]]}},"alternative-id":["s222410013"],"URL":"https:\/\/doi.org\/10.3390\/s222410013","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,12,19]]}}}