Abstract: The most important device in the ternary optical computer(TOC) is ternary optical processor, and many studies in this field have been done. So far, the TOC adder based on MSI)mainly rewrites the addend and summand to MSD format. After that, l}, W transformations arc first applied respectively, then the outputs of them arc as the input of T'，W' transformations, at last T transformation is used to achieve carry-free addition operation. In this paper, the above addition algorithm was improved, and a new computing method was put forward. According to this method,for the two MSD data,first use T,W transformations,then use T',W' transformations,at the third step use W' transformation to achieve carry-free addition operation. The feasibility and validity of this method are proved theoretically and experimentally. In this way, in some sense, it can reduce the number of basic elements in optical adder, which will decrease the design difficulty, and provide a new approach for the design of the optical adder.

Key words: Ternary optical computer(TOC) , TOC adder, MSD