Konishiroku Photo Industry Co. said it intends to begin a $16.38-million tender offer Friday for the 40% of Fotomat that it doesn't already own. Konishiroku, which owns 60% of Fotomat's 25.2 million outstanding shares, said it will pay $1.62 1/2 a share in cash for the remaining 10.08 million shares. The Tokyo-based company said that if it obtains two-thirds of the outstanding stock through the tender offer, it will merge the St. Petersburg, Fla., company with a Konishiroku subsidiary at the same price. Fotomat shares, which are traded on the American Stock Exchange, closed at $1.62 1/2, up 62 1/2 cents a share from Friday's close. Fotomat sells photographic merchandise and photo finishing services.