Grayscale lithography methods and devices

A method of increasing available graytone levels for use in a lithographic process, the method comprising:

• determining a unit cell size in response to a designed part geometry;
• generating a set of distinct quadrilateral areas such that each area fits within a unit cell;
• removing redundant quadrilateral areas from the set,
• associating each graytone level with a distinct quadrilateral area;
• and
• correlating each graytone level with a distinct unit cell fill factor.

A diffraction grating produced using a lithography process, the lithography process comprising the steps of:

• generating a mask having a periodic arrangement of a plurality of selectively filled unit cells, each unit cell partially filled with a fractional area selected from a set of square and rectangular areas, each area corresponding to a gray tone level;
• depositing a photoresist layer on a substrate;
• exposing the photoresist layer to radiation selectively transmitted by the areas of the mask;
• developing the photoresist layer such that a periodic arrangement of photoresist
• mesa structures result;
• and etching the mesa structures and substrate.