Union Kōgaku K.K. (ユニオン光学株式会社) was a Japanese company that sold the Union Semi in 1953–4 (a rebadged Zenobia) and perhaps the Union Model U at an unknown date. According to a 1953 advertisement, Union Kōgaku was a microscope maker and the Union Semi was its first camera.
A company with the same name still (2007) exists and makes microscopes and other optical devices. It was founded in 1991, but it is a subsidiary of a company called Union Holdings K.K. (ユニオンホールディングス株式会社) founded in 1948.
- Asahi Camera (アサヒカメラ) editorial staff. Shōwa 10–40nen kōkoku ni miru kokusan kamera no rekishi (昭和10–40年広告にみる国産カメラの歴史, Japanese camera history as seen in advertisements, 1935–1965). Tokyo: Asahi Shinbunsha, 1994. ISBN 4-02-330312-7. Item 975.