To test the precision of projected light patterns, a series of line triplets of differing size and spacing were projected onto a neutral density filter (Figure \ref{993179}). The resulting camera images were then analysed by averaging the intensity for each pixel row. High precision projected patterns would result in clear differences in light intensity for even closely spaced lines.
Light spectra measurements
Another key feature of the DOME is the ability for each projected pixel to have a different colour. This offers the means to provide multiple light-signals to different agents and supports multiplexed communications for more complex behavioural control. This capability is possible due to the projector containing three separate LEDs for red, green and blue light. As living microagents are often sensitive to specific wavelengths of light, we characterised the light spectra of each LED separately. The light spectra produced by the projection module was performed using a calibrated spectrophotometer (Ocean Optics). To collect the readings the optical fibre used for measurement was attached to the DOME at the sample plane facing upwards. The projector was set to a full screen display where all pixels had value (0, 0, 255), (0, 255, 0) or (255, 0, 0) respectively for red, blue and green.