Found this yesterday:
https://www.tokaicom.co.jp/original/swich.html
On the third row is 「光スイッチ」 (optical switch), an optical switch that appears to take Alps keycaps.
Here is the original page on their old site with specifications and datasheet:
http://web.archive.org/web/201312100036 ... detail.htm
(Tokai have just gone bankrupt apparently.)
Tokai SPT-0101 optical switch
- Daniel Beardsmore
- Location: Hertfordshire, England
- Main keyboard: Filco Majestouch 1 (home)/Poker II backlit (work)
- Main mouse: MS IMO 1.1
- Favorite switch: Probably not whatever I wrote here
- DT Pro Member: -
- Contact: