This interesting photo shows a 466 portable storage oscilloscope on the left and a rather unique instrument on the right. This instrument has two CRTs with the mechanical construction, knobs, and graticule lights similar to the 511 introduced in 1947. The slowest sweep rate is 1 second which would not display well on this CRT.
Miles Tippery writes in his book about a number of custom products Tektronix did in the early days including one of the first for a doctor doing experimental work on heart problems.The oscilloscope was fitted with a camera so that the display could be recorded on film. Might this be that product? The 466 oscilloscope might be shown to contrast how slow signals could now be displayed on a storage oscilloscope. This higher resolution photo was was featured as our August 2020 Photo of the Month.
Contact the museum if you have any information on this mystery instrument.