Cross Validated Confocal Volume Characterization Using FCS and PSF Analysis

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DOI:

https://doi.org/10.4302/plp.v18i3.1390

Abstract

Accurate confocal volume characterization is fundamental to quantitative Fluorescence Correlation Spectroscopy (FCS) and confocal microscopy measurements. Refractive index mismatches and localized thermal effects can systematically distort biophysical parameters (diffusion coefficients, molecular concentrations) if not properly calibrated. This study cross-validates two complementary approaches for confocal volume characterization: FCS (using fluorescent molecules of known or unknown concentration) and direct Point Spread Function (PSF) measurement using sub-diffraction fluorescent beads, to assess accuracy in determining the effective confocal volume Veff , beam waist w0, structural parameter s, diffusion time τ_D, diffusion coefficient D, and correlation amplitude G_0. FCS and PSF yielded closely matched effective volumes of 0.89 fL and 0.84 fL, respectively.

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Author Biographies

Lazhar LALAOUI, Mechanical Engineering Department, Faculty of Technology University of Setif -1-

I'm currently a lecturer in Optics at the University of Sétif 1 (Ferhat Abbas), Algeria. My research expertise encompasses Engineering Optics, FِِCS, advanced microscopy techniques, and the optimization of solar cell efficiency. My most recent publication, "Axial Point Spread Function Modeling by Application of Effective Medium Approximations: Widefield Microscopy," highlights my work in developing innovative approaches to improve optical imaging systems.

Hossam TAALLAH, Laboratery of Applied Optics

Lecturer at the Institute of Optics and Precision Mechanics (IOMP), University of Sétif 1, Algeria.

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Published

2026-10-18

How to Cite

[1]
L. LALAOUI and H. TAALLAH, “Cross Validated Confocal Volume Characterization Using FCS and PSF Analysis”, Photonics Lett. Pol., vol. 18, no. 3, pp. 38–40, Oct. 2026.

Issue

Vol. 18 No. 3 (2026): Photonics Letters of Poland Vol.18 No.3

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Articles

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Copyright (c) 2026 Lazhar LALAOUI, Hossam TAALLAH

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