Fig. 3: Examples of bulk free-space optical encoders.

a Passive phase mask and 4f-system. Reprinted from ref. 27 under a CC BY license. b SLMs for optical front-end with digital back-end. Reprinted from ref. 30. ©The Authors, some rights reserved; exclusive licensee AAAS. Distributed under a CC BY-NC 4.0 license http://creativecommons.org/licenses/by-nc/4.0/”. Reprinted with permission from AAAS. c SLMs for all-optical processor. Reprinted with permission from ref. 33 ©Optical Society of America.