July 30, 1984

Posters of pinup girls dot the walls, and a giant picture of a Playboy bunny is painted on the side of the Van de Graaf accelerator. This laboratory, which takes up only one floor of a nondescript Fujitsu Ltd. building, hardly seems like the kind of place that would unnerve American industry. But the Optoelectronics Joint Research Laboratory is indeed the center of one of those industrial efforts funded by Japan's Government for which the nation is known. The mission of the laboratory's 50 researchers, who pad about the place in slippers, is to spearhead Japan's thrust into the emerging field of optoelectronics - the combination of light, usually from lasers, and electronics. Optoelectronic technology is used now mainly to provide long-distance telephone communications through hair-thin glass optical fibers that can transmit information hundreds of times faster than conventional copper wires.

She had prepared all year for this race, knowing it would be her last, but with 50 meters left, she was coming up short on the 79-kilometer road race. Connie Carpenter was a few centimeters behind Rebecca Twigg, all the difference between gold and silver. With a furious thrust of her bicycle at the finish line, Miss Carpenter caught her younger rival to win the first American cycling medal since 1912, in the first Olympic cycling race for women. A long and hot afternoon later, Alexi Grewal of the United States, who was nearly disqualified from the Summer Games last week because of a doping discrepancy, surged past Steve Bauer of Canada for the second United States gold medal of the day, in the men's 190-kilometer road race. The two narrow finishes stirred up the tens of thousands of sun-baked fans enjoying one of the few free events in these high-priced Summer Games. People chanted ''U.S.A.'' as the United States proved it has come of age in one of the world's most popular sports.

Foreign Minister Andrei A. Gromyko was quoted today as saying he did not expect negotiations to be held in September on banning weapons in space. Former Senator George S. McGovern, who is here on a private visit, said Mr. Gromyko made the statement Friday during a three-hour conversation between the two men in Yalta. Mr. McGovern, a South Dakota Democrat, said that Mr. Gromyko also predicted that President Reagan would be re-elected and that if he was, the Soviet Foreign Minister did not expect ''productive'' American-Soviet relations for the next four years. 'Very Pessimistic' Of Mr. Gromyko's view of the prospects for space arms talks between the Russians and the Americans, Mr. McGovern said: ''He's very pessimistic about it. He doesn't expect the talks to go forward now.''

Brazil has decided to follow Mexico's example in seeking to postpone all principal payments coming due on its debts for the next several years, according to officials here. The request is expected to be made when Brazil resumes debt negotiations with foreign banks in New York this week. Foreign bankers and economists said that, if successful, the Mexican and Brazilian attempts to obtain multiyear reschedulings could mark a turning point in the two-year-old regional debt crisis by providing the two largest debtors with time to rebuild their troubled economies. At the London economic summit conference last month and in other forums, officials of the industrial nations have been urging that those debtor countries that make an effort to control inflation and reduce international payments deficits should receive favored treatment on their debts. Models for the Region By easing conditions for Brazil and Mexico, analysts say, both nations' austerity programs could become regional models.

Lambert Pohner has seen the snout. The small butterfly, named for what looks like a long, skinny nose protruding from its head, is rare in New York City, and urban butterfly watchers speak of it reverently as ''the legendary snout.'' Mr. Pohner says he has sighted eight snouts so far this summer, all in Central Park. ''This is the summer of the snout,'' said Mr. Pohner, who has seen more than 40 summers come and go in the park during the years he has monitored the wildlife there. In summers past, he said, he considered himself lucky if he saw a single snout.