The role and importance of impurities in the power exhaust of tokamak fusion reactors is long-established, and so too are the negative effects such impurities have on the effectiveness of these devices and the lifetime of their components. It is therefore essential for the development of future fusion devices, such as ITER and DEMO, that a comprehensive understanding of impurity behaviour be obtained. Currently, impurity understanding is primarily based on computational models validated using diagnostics with limited coverage and/or spatial resolution. For this reason, it is desirable for fusion devices to use imaging systems where possible. This thesis presents a new analysis technique for multi-delay coherence imaging spectroscopy (CIS), a narrowband interferometric spectral imaging diagnostic. This technique, based on the Doppler shift and broadening of impurity spectra, enables simultaneous measurement of impurity velocities and temperatures in 2D with a high spatial resolution. We focus on C III emission, an abundant impurity in carbon-walled fusion devices, and present how the negative effects of spectral contamination and the complex spectral structure of C III are mitigated by this analysis technique using multiple fixed interferometer delays. We present the first use of a triple-delay CIS system on a fusion device and discuss the effect its installation within the Multi-Wavelength Imaging (MWI) diagnostic has on measurements. Additionally, we present further development of accepted CIS calibration procedures and suggest modifications to the diagnostic, enabling greater usability and cementing coherence imaging spectroscopy as a cost-effective and powerful diagnostic in the development of fusion devices.