holograph

A handwritten document that is solely the work of the person whose signature it bears, especially a letter, deed, or will; an original manuscript, a protograph.

A hologram.

But when a holograph is placed backwards in its holder and illuminated with laser light, it can produce a real image […]

Producing a holograph involves illumination of an object through the use of intersecting laser beams.

To record by means of holography.

Handwritten by the person whose signature it bears.

The will was holograph, for Mr. Utterson, though he took charge of it now that it was made, had refused to lend the least assistance in the making of it;