An illumination optical system configured to form a stitched line image on an imaging member, comprising: first and second illumination modules, each illumination module including: a light source configured to generate a light beam, a light guide adjacent the light source to transport the light beam from the light source, a DMD array having an array of micromirrors in 2D configuration tilted around a diagonal axis, the DMD array of micromirrors being planar with a row direction and a column direction orthogonal to the row direction, both the row direction and the column direction being within the plane of the DMD array, the light beam being transported by the light guide and out of an exit face of the light guide, and a Refractive Total Internal Reflection (RTIR) prism that receives the light beam from the light guide and redirects the light beam to the DMD array, the RTIR prism including a 45-45-90 degree prism and a second prism, the second prism having a 45 degree bottom face above a top face of the 45-45-90 degree prism with an airspace gap therebetween, the 45-45-90 degree prism having an bottom face mounted parallel to the plane of the DMD array, the DMD array configured to modulate the light beam and generate an image as reflected image output beams, the 45-45-90 degree prism configured to direct the image output beams to the imaging member via a projection optical system, wherein the exit face of the light guide is slanted with respect to the normal of the axis of the light guide such that the light beam is transported out of the exit face at a compound angle relative to the row and column directions, or wherein the second prism is a compound angle prism having a top face that is angled such that the light beam is redirected to the DMD array along a compound angle relative to the row and column directions; and a DMD housing containing the DMD array, the DMD housing having a width, the illumination module being confined within the width of the DMD housing, wherein the second illumination module is stacked against the first illumination module in a side-by-side configuration for stitching of the image output beams of the first and second illumination modules into an image line parallel to the row direction of the DMD arrays, wherein a compound angle corresponds to directions deviating from the normal direction of the DMD array plane in the row and column direction. first and second illumination modules, each illumination module including: a light source configured to generate a light beam, a light guide adjacent the light source to transport the light beam from the light source, a DMD array having an array of micromirrors in 2D configuration tilted around a diagonal axis, the DMD array of micromirrors being planar with a row direction and a column direction orthogonal to the row direction, both the row direction and the column direction being within the plane of the DMD array, the light beam being transported by the light guide and out of an exit face of the light guide, and a Refractive Total Internal Reflection (RTIR) prism that receives the light beam from the light guide and redirects the light beam to the DMD array, the RTIR prism including a 45-45-90 degree prism and a second prism, the second prism having a 45 degree bottom face above a top face of the 45-45-90 degree prism with an airspace gap therebetween, the 45-45-90 degree prism having an bottom face mounted parallel to the plane of the DMD array, the DMD array configured to modulate the light beam and generate an image as reflected image output beams, the 45-45-90 degree prism configured to direct the image output beams to the imaging member via a projection optical system, a light source configured to generate a light beam, a light guide adjacent the light source to transport the light beam from the light source, a DMD array having an array of micromirrors in 2D configuration tilted around a diagonal axis, the DMD array of micromirrors being planar with a row direction and a column direction orthogonal to the row direction, both the row direction and the column direction being within the plane of the DMD array, the light beam being transported by the light guide and out of an exit face of the light guide, and a Refractive Total Internal Reflection (RTIR) prism that receives the light beam from the light guide and redirects the light beam to the DMD array, the RTIR prism including a 45-45-90 degree prism and a second prism, the second prism having a 45 degree bottom face above a top face of the 45-45-90 degree prism with an airspace gap therebetween, the 45-45-90 degree prism having an bottom face mounted parallel to the plane of the DMD array, the DMD array configured to modulate the light beam and generate an image as reflected image output beams, the 45-45-90 degree prism configured to direct the image output beams to the imaging member via a projection optical system, wherein the exit face of the light guide is slanted with respect to the normal of the axis of the light guide such that the light beam is transported out of the exit face at a compound angle relative to the row and column directions, or wherein the second prism is a compound angle prism having a top face that is angled such that the light beam is redirected to the DMD array along a compound angle relative to the row and column directions; and a DMD housing containing the DMD array, the DMD housing having a width, the illumination module being confined within the width of the DMD housing,