Table 4
Summary of optical diagnostic techniques that could be used in ECN spray vessels [31].
| Method | Temperature range min/max (°C) | Response/transient capability | Accuracy | Commercially available/relative cost | General description |
|---|---|---|---|---|---|
| Rayleigh scattering | 20/2500 | Very fast/yes [43] | 1% | No/very high | Non-intrusive. |
| Can be susceptible to background interference. | |||||
| Raman scattering | 20/2227 | Very fast/yes [44] | 7% | No/very high | Non-intrusive. |
| 2% [45] | |||||
| Coherent Anti-Stokes Raman Scattering (CARS) | 20/2000 | Fast/NA | 5% | Yes/very high | Non-intrusive. |
| Laser Induced Fluorescence (LIF) | 0/2700 | Very fast/yes | 10% | No/very high | Non-intrusive. Can be limited by quenching phenomena. |
| Laser absorption spectroscopy | 20/2500 | Very fast/yes [40] | 15% | Yes/low | Non-intrusive. Line of sight averaging (limited special resolution). |
| 5% [40] | |||||
| Thermographic phosphors | −250/2000 | Very fast/yes | 0.1–5% | Yes/high | Semi-intrusive. |
| Interferometry | 0/2300 | Fast/yes | 1.4–5% [41, 42] | No/high | Non-intrusive. |
| Laser Induced Grating Spectroscopy (LIGS) |