Diffractive optical element fabrication

A diffractive optical element including:

• an input surface configured to receive an input optical beam;
• a diffractive surface adapted to spatially disperse the input optical beam into a dispersed signal;
• an output surface configured to output the dispersed signal;
• wherein the output surface and the diffractive surface are non-parallel;
• and
• wherein diffractive surface is formed in situ by a photolithographic technique.

A diffractive optical element including:

• an input surface configured to receive an input optical signal;
• a diffractive surface adapted to spatially disperse the input optical beam into a dispersed signal;
• an output surface configured to output the dispersed signal;
• wherein the input surface and the diffractive surface are separated by a distance of greater than 5 mm;
• and
• wherein the diffractive surface is formed in situ by a photolithographic technique.

A method of fabricating a diffractive optical element, the method including the steps:

• depositing a pattern material layer of pattern material directly onto a first surface of a non-cuboid prism, wherein the first surface is non parallel to either or both of an input surface configured to receive an input optical signal and an output surface configured to output a dispersed signal from the diffractive optical element;
• applying a photoresist layer to the pattern material layer;
• creating a diffractive pattern in the photoresist layer;
• and
• transferring the diffractive pattern in the photoresist layer to the pattern material layer to define a diffractive surface on the first surface.