Device for processing light/optical radiation, method and system for designing such a device

A device for processing a light radiation comprising:

• at least two reflective optical elements defining a multi-pass cavity in which the light radiation travels back-and-forth so that each reflective optical element reflects the light radiation at least four times;
• at least one corrective element, comprising:
• one of the reflective optical elements defining the multi-pass cavity;
• and/or
• a corrective element placed in the multi-pass cavity and different from the reflective optical elements defining the multi-pass cavity;
• the at least one corrective element having at least one corrective position producing a reflection or a transmission of the light radiation and having an irregular surface so that the spatial phase profile of the at least one corrective position has a different phase shift for several different reflection/transmission points of the at least one corrective position, and wherein the irregular surface presents irregularities of the at least one corrective position having spatial structures at least five times smaller than the total size of the at least one corrective position;
• and
• wherein the device does not include any lens, polarizing element, or optical coupler between the at least two reflective optical elements defining the multi-pass cavity through which the light radiation passes as the light radiation is reflected within the multi-pass cavity.