TVI Corp., a Beltsville maker of thermal targets for the military and radiant heating panels for commercial and residential use, last week announced that it intends to diversify into the medical service business with the acquisition of Trilogic Corp. of Reston.

TVI has signed a letter of intent to purchase Trilogic, a manufacturer of automated instruments used by ophthalmologists and optometrists, in an exchange of stock between the two companies. Terms of the deal were not disclosed.

TVI, a publicly owned company with $4 million in revenue last year, will add about $2.2 million in annual sales in the deal.

In addition to Trilogic's main product, an instrument designed to ensure rapid, accurate prescriptions for eyeglasses, the 13-year-old company develops and distributes a computer system designed to fully computerize medical practices.

Commenting on the acquisition, TVI President Charles R. McConnell said: "The addition of the Trilogic group will not only provide a successful product that broadens TVI's opportunities in the commercial marketplace, but will also make available experienced and highly qualified management and engineering personnel. . . . "

Citibank Maryland N.A. has selected a 28-story, downtown Baltimore office building as the company's headquarters, Margaret Alton, the company's chairman, announced last week.

Citibank, a subsidiary of the New York-based banking giant Citicorp, will begin its banking operations July 1 as specified by legislation passed last year in the Maryland General Assembly. The legislation allowed Citicorp to begin full-service banking in Maryland in exchange for certain employment and investment requirements.

Citibank Maryland said it has leased the ground floor and mezzanine of 6 St. Paul Centre in the city's financial district. The new facilities comprise more than 8,800 square feet for what will be its first full-service retail-banking branch in the state.

In addition, the company has leased two full floors for its administrative offices and has an option through Sept. 1 for three additional floors, it said.

According to Frederic Oliver, vice president and director of marketing for S/A Associates, which purchased the office tower last December from Chase Bank, Citibank plans to open the branch on July 1.

The building is situated at the intersection of Baltimore and St. Paul streets at the hub of the city's commercial district.

BDM International Inc. in McLean has won a $21.6 million increase in a 10-year contract to provide the Air Force Logistics Command with a new computer system. The increase plus a $14 million addition announced earlier bring total revenue from the contract to $120 million, the company's largest single award, according to Earle C. Williams, president of the diversified professional and technical service firm.

Science Applications Research, a joint venture in Lanham, has won a five-year, $18.4 million contract to provide computer programming, operations and scientific support to the National Space Science Data Center at the Goddard Space Flight Center in Greenbelt. SAR is a partnership between SASC Technologies and RMS Technologies.

Dynalectron Corp., a diversified technical services firm, last week said its subsidiaries received more than $24 million in new electrical and mechanical contract awards in the first quarter. Dan Bannister, president of the McLean company, said the contracts include automotive facilities in Atlanta and Canada, a computer support center in Idaho, a hydroelectric plant in Canada, and office buildings in Wilmington, Del., Washington and Miami.