University of Oulu

T. Talala et al., "Time-Resolved Raman Spectrometer With High Fluorescence Rejection Based on a CMOS SPAD Line Sensor and a 573-nm Pulsed Laser," in IEEE Transactions on Instrumentation and Measurement, vol. 70, pp. 1-10, 2021, Art no. 6004110, doi: 10.1109/TIM.2021.3054679

Time-resolved raman spectrometer with high fluorescence rejection based on a CMOS SPAD line sensor and a 573-nm pulsed laser

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Author: Talala, Tuomo1; Kaikkonen, Ville A.2; Keränen, Pekka1;
Organizations: 1Circuits and Systems Research Unit, University of Oulu, Oulu, Finland
2Optoelectronics and Measurement Techniques Research Unit, University of Oulu, Oulu, Finland
3Optoelectronics Research Centre, Physics Unit, Tampere University, Tampere, Finland
4Fraunhofer Centre for Applied Photonics, Fraunhofer UK Research Ltd., Glasgow, U.K.
5Institute of Photonics, SUPA, University of Strathclyde, Glasgow, U.K.
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.2 MB)
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Language: English
Published: Institute of Electrical and Electronics Engineers, 2021
Publish Date: 2021-05-04


A time-resolved Raman spectrometer is demonstrated based on a 256 × 8 single-photon avalanche diodes fabricated in CMOS technology (CMOS SPAD) line sensor and a 573-nm fiber-coupled diamond Raman laser delivering pulses with duration below 100-ps full-width at half-maximum (FWHM). The collected backscattered light from the sample is dispersed on the line sensor using a custom volume holographic grating having 1800 lines/mm. Efficient fluorescence rejection in the Raman measurements is achieved due to a combination of time gating on sub-100-ps time scale and a 573-nm excitation wavelength. To demonstrate the performance of the spectrometer, fluorescent oil samples were measured. For organic sesame seed oil having a continuous wave (CW) mode fluorescence-to-Raman ratio of 10.5 and a fluorescence lifetime of 2.7 ns, a signal-to-distortion value of 76.2 was achieved. For roasted sesame seed oil having a CW mode fluorescence-to-Raman ratio of 82 and a fluorescence lifetime of 2.2 ns, a signal-to-distortion value of 28.2 was achieved. In both cases, the fluorescence-to-Raman ratio was reduced by a factor of 24—25 owing to time gating. For organic oil, spectral distortion was dominated by dark counts, while for the more fluorescent roasted oil, the main source of spectral distortion was timing skew of the sensor. With the presented postprocessing techniques, the level of distortion could be reduced by 88%-89% for both samples. Compared with common 532-nm excitation, approximately 73% lower fluorescence-to-Raman ratio was observed for 573-nm excitation when analyzing the organic sesame seed oil.

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Series: IEEE transactions on instrumentation and measurement
ISSN: 0018-9456
ISSN-E: 1557-9662
ISSN-L: 0018-9456
Volume: 70
Article number: 9335980
DOI: 10.1109/TIM.2021.3054679
Type of Publication: A1 Journal article – refereed
Field of Science: 213 Electronic, automation and communications engineering, electronics
Funding: The work at the University of Oulu was supported by the Academy of Finland, under Contract 314404, Contract 323719, and Contract 314405. The work at Tampere University was supported in part by the Academy of Finland, under Contract 281955 and in part by the Co-Innovation Project of Business Finland, “3DLidar.” The work at Strathclyde was supported in part by the European Research Council under Grant 278389 and Grant 727738, in part by the UK EPSRC under Grant EP/P00041X/1 and Grant EP/L015315/1, in part by the Fraunhofer UK Research Ltd., in part by the Royal Academy of Engineering, and in part by the Element 6 (UK) Ltd.
Academy of Finland Grant Number: 314404
Detailed Information: 314404 (Academy of Finland Funding decision)
323719 (Academy of Finland Funding decision)
314405 (Academy of Finland Funding decision)
Copyright information: © The Authors 2021. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License. For more information, see