In (a), an optical micrograph of a printed diffraction grating with a nominal layer thickness 10 μm. In (b), an optical micrograph of a printed diffraction grating with a nominal layer thickness of 25 μm. In (c), an optical micrograph of a printed diffraction grating with a nominal layer thickness of 50 μm. All micrographs taken at a magnification of 500×. A scale bar in the bottom right of each image is equal to 30 μm