2 inch Hitachi HS124E image orthicon tubes

[Aussie Bloke]

G'day all.

I have recently bought from Ebay a couple of Hitachi HS124E image orthicon tubes http://cgi.ebay.com.au/ws/eBayISAPI....m=230565349814 , when they arrived I was very surprised to know they were smaller than I expected!!! I was expecting them to be 3 inch but it turns out they are 2 inch in size!!! Till now I thought image orthicon tubes only came in 3 inch and 4.5 inch variety, but after receiving these tubes and doing some research there were indeed 2 inch image orthicon tubes. I haven't found much info on them but from what I have found NHK in Japan invented them around 1965 and they have some advantages over the 3 inch IOs according to some reviews and they were used for medical/industrial purposes and perhaps for space photography.

I was wondering if anyone here knows more about these 2 inch IO tubes and exactly what applications they were used for and what kind of cameras used them? Also were these 2 inch IO tubes used in B&W or colour broadcast cameras back in the day or were they used for industrial/medical applications only?

Also the IO tube box was a clear plastic cylinder with a funnel and a ball bearing inside, what is that part and what is it used for?

I have attached a few images for you all to see including that little plastic part, one of the images I have placed a 3 inch IO beside the 2 inch IO for comparison.