We present a simplified, integrated PIV–LIF system that enables the simultaneous measurement of ve-locity and temperature fields in aqueous flows. The system employs a novel temperature-sensitive fluo-rescent dye (RuPhen), a continuous-wave diode laser, and a single RGB color camera.

RuPhen proves particularly suitable for this application due to its strong temperature-dependent emis-sion (sensitivity: 4%/°C), peak absorption at 450 nm, and peak emission at 605 nm. The resulting large Stokes shift between excitation and emission wavelengths not only separates the fluorescence from Mie-scattered light but also enables efficient signal channeling within the RGB spectrum of the camera.

To account for laser power fluctuations during measurements, we introduce a new correction method based on the combined analysis of two photoluminescent signals. We further provide a spectral charac-terization of RuPhen across a range of temperatures and detail the rationale behind each component of our system design.

The effectiveness of the proposed method is demonstrated through two experimental test cases that fo-cus on thermally driven and turbulent flow regimes. These tests highlight the system’s potential for real-time, spatially resolved diagnostics in complex thermal flow environments.