Photogram is the word in Lyra's world for "photograph".
Lord Asriel would insert a slide into the frame of the Projecting lantern, a photogram appears on the linen screen. A photogram is the picture that was taken. One photogram was taken with a standard silver nitrate emulsion. A photogram that shows Dust was taken with a special emulsion. A photogram of the Aurora, also known as Northern Lights taken with the special emulsion showed a city in another world
Quotation In The Book
| "That photogram was taken with a standard silver nitrate emulsion," Lord Asriel said. "I'd like you to look at another one, taken from the same spot only a minute later, with a new specially prepared emulsion."
"He lifted out the first slide and dropped another into the frame. This was much darker; it was as if the moonlight had been filtered out."
"It registered as light on the plate because particles of Dust affect this emulsion as photons effect silver nitrate emulsion."
Northern Lights - pages: 21. 22. 23.