Reverse Engineering – Rayography (The Kiss) (1922) Used Camera Techniques?

I looked at some surrealistic photographers and stumbled upon Man Ray. I wondered what camera techniques were used in this picture.

(If you do not want to talk about camera techniques, you can comment on the ideas in this photo or other aspects that may interest you.)
A good link is also: https://www.theartstory.org/artist-ray-man.htm

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