Digital lithography apparatus with imaging device positioned to mitigate Moire effect

A system, comprising:

• a light source configured to emit a beam of light;
• a digital micro-mirror device (DMD) configured to receive the beam of light and form an output light beam;
• one or more optical elements configured to direct the output light beam along a first optical path from the DMD to a surface of a substrate, wherein the first optical path has a first optical length from the DMD to the surface of the substrate;
• and
• an image sensor configured to capture an image of the substrate illuminated by the output light beam via a second optical path, wherein the second optical path has a second optical length from the surface of the substrate to the image sensor, wherein the first optical length and the second optical length are unequal;
• and
• a lens along a shared portion of the first optical path and the second optical path, wherein the output light beam emitted from the DMD is focused on the surface of the substrate when the lens is in a first position, and wherein the image of the substrate captured by the image sensor is focused when the lens is in a second position.

A method, comprising:

• illuminating, by a first light source configured to output a beam of light, at least a portion of a substrate with an output light beam via a first optical path, wherein the output light beam is formed by a digital micro-mirror device (DMD), wherein the first optical path has a first optical length from the DMD to a surface of the substrate;
• capturing, by an imaging device, a first image of the substrate illuminated by the output light beam via a second optical path, wherein the second optical path has a second optical length from the surface of the substrate to the imaging device;
• determining, by a processing device, whether the first image of the substrate comprises a Moire effect;
• responsive to determining that the first image of the substrate comprises the Moire effect, adjusting the second optical path length, wherein the first optical path length and the adjusted second optical path length are unequal;
• and
• causing a movable lens disposed along a shared portion of the first optical path and the second optical path to move between a first position and a second position, wherein the output light beam emitted from the DMD is focused on the surface of the substrate when the movable lens is in the first position, and wherein the image of the substrate captured by the imaging device is focused when the movable lens is in the second position.