Could be a lens mount designation, mine says "Kodak FLURO EKTAR f:1.5 111mm Mag.1:6 ES330(L)" The L is in a circle. "Made in U.S.A. by Eastman Kodak Co. Rochester N.Y."
Most likely, the 'RA 111' is the serial number of the lens. Kodak is well know to have encoded the year of manufacture into the first two letters of the serial number. The not-so-secret decoder is as follows:
C-A-M-E-R-O-S-I-T-Y
1-2--3-4-5--6-7-8-9-0
RA means the lens was made in 1952 (R-->5 and A-->2 ==> 1952)
the ES on Bob's lens indicates that his lens was manufacured in 1947 (E-->4, s--->7 ==> 1947).
My dad worked for the X-Ray division of GE, the lens came out of a scrapped machine way back in the 1960's. At the moment, it sits on my desk and is used as a stand for the TV remote control. It is a real good paper weight as well. They are only corrected for the green light from a phospher on an image intensifier screen. They sort of work ok for photography if you use a green filter. No iris, no shutter and it weighs over 2kg. Also comes with a ton of chromatic aberration as well.
Great information. I wrote to Eastman House about their final format , lens film distance at infinity and the history. I think they return in 2 weeks. I will write here.
Only corrected to green color lens ? It means only green green grass will appear sharp ? May be other colors will appear like an rainbow ? What a death investment !