MINNETONKA, Minn., June 1 -- ADC Telecommunications Inc. has announced that it will pay $105 million to acquire Spectracom, a manufacturer of components used in fiber-optic networks. The acquisition, expected to be finalized by late June, calls for ADC to pay $60 million in cash, with an additional $45 million payable contingent on future technology developments.This will be ADC's third acquisition in the optical components field in four years. In 1995, ADC bought Australia-based AOFR, a fiber coupler manufacturer. Last year the company bought Princeton Optics, which manufactures parts that align mirrors, prisms and lenses used in optical devices.