To get to net zero, we need to mitigate emissions of gases that are potentially hazardous, by improving the technology used to detect gas leaks. Gases of interest include methane, a strong greenhouse gas, ammonia, proposed for energy storage and transport as part of the hydrogen economy, and others. To enable safety and minimise environmental emissions, a new generation of gas leak detectors is needed to support this change. This project concerns the development of a prototype optical gas detector for use in "standoff" mode, allowing operators to detect gas leaks from a distance. This technology has the benefit of high sensitivity and specificity to individual gases. The project will involve development of the sensor, incorporating a new generation of high-performance components such as ultra-low-noise photodetectors, performance characterisation and optimisation, and potentially field testing. Opportunities to apply this technology to other gases will also be explored, especially for applications in marine transportation.