Tomioka lenses are generally very good quality lenses, you can find Tomioka lenses behind many different brands like Porst, Vivitar, Ricoh,Chinon etc. In next the next paragraphs you can read about this great Japanese company history.
Tomioka Optical Company, Ltd. had its origins in 1924, when Masashige Tomioka started a laboratory called Tomioka Kogaku Kenkusho in the Shin-agawa district of Tokyo to develop photographic lenses, designing optical products for military and industrial clients. After a long period of trial and error, he eventually developed a respectable four-element f/4.5 "Tessar" type photographic lens using only Japanese-made glass and named it "Lausar." In 1932 the laboratory was extended into a manufacturing facility and renamed Tomioka Kogaku Kikai Seizosho.
From 1933, Tomioka became an OEM lens manufacturer for camera companies such as the Proud K.K. During this period, several high-quality lens manufacturers were operating, but costs and volumes led to domestice lenses costing more than equivalent German imports, so growth was limited. After the war, in austerity conditions, Tomioka switched to the mass market and developed a basic triple-element lens called "Tri-Lausar" which was its most widely used product. From late 1949, it became the exclusive lens supplier for Yashica, becoming a Yashica affiliate/subsidiary in 1968, and named the Tomioka Optical Corporation from 1969.
It is interesting to note that most of the Japanese lens manufacturers had started by copying the Carl Zeiss "Tessar" formula as their first high-quality photographic objective. The Hexar, Promar, Anytar, Zuiko, Lausar, Simlar and Rokkor all fall into this category. Tomioka made lenses for various outfits (for example, they made the 45mm f2.8 on the old Ricoh 500 RF, and for several other similar-era Japanese RF´s). Their products can often be found by the labels Tominon (Polaroid Studio equipment & higher-end cameras), Tomi-Yashinon (Yashica magnifying and macro lenses) Tomi-Kogaku, Auto-Tominon.
In 1983 Tomioka become one member of the Kyocera ceramic group following its takeover of Yashica. It became the Kyocera Optics deivision and is still in business under this name. The Tomioka plant is the one where Carl Zeiss lenses are/were manufactured under contract for Japanese cameras (Carl Zeiss Japan).
Source: "The Evolution of the Japanese camera", Condax and others, publ. International Museum of Photography, Rochester, NY, 1984.