Except when they hid behind playful masks, designers Charles and Ray Eames usually posed for photographs in exuberant smiles, beaming with optimism. The pose was fitting.

This husband-and-wife team, headquartered in Los Angeles, excited the world of design in the heady years after World War II when Americans looked ever upward and onward--before Vietnam and racial violence and the homeless gnawed at the nation’s conscience and dampened good feelings.

Charles and Ray Eames designed the form-fitting chairs that are so ubiquitous now we forget how dramatic and modern the invention once seemed. They housed their offices in an old auto garage on Washington Boulevard in Venice, encouraging the new fad for transforming factory lofts into galleries and studios. They influenced modern architecture by building a box-like steel and glass home on the Pacific Palisades. And they manipulated a host of different media to bombard the public with images and ideas about a streamlined, modern world anchored in science and technology.

A little more than 20 years after the death of Charles and a little more than 10 years after the death of Ray, their work is being celebrated by an unusual exhibition now at the Library of Congress here. The library, which has a bountiful collection of the papers of the Eameses, and the Vitra Design Museum of Germany, which owns many samples of their furniture, put the materials together to produce the show called “The Work of Charles and Ray Eames: A Legacy of Invention.”

After several stops in Europe, the exhibition opened here for a stay through Sept. 4. It goes on to the Cooper-Hewitt Design Museum in New York and the St. Louis Art Museum before reaching the Los Angeles County Museum of Art on June 25, 2000. After almost three months in Los Angeles, the exhibition then heads for its final site, the Pacific Science Center in Seattle.

On first glance, the noisy and cluttered mood of the exhibition seems out of place in a library or a museum. Videos blare away. Glass boxes are crammed with letters, mementos and photos. Posters cover the walls. So do life-size portraits. Visitors hold earphones to hear the Eameses’ friends and colleagues describe their life. Models and molds and pieces of furniture abound.

The clutter and noise are not accidental. The exhibition takes on the feel and pace of the frenetic Eames Offices in Venice. And it resembles the way the Eameses would try to overwhelm the senses of visitors to their own exhibitions.

The show may enhance the reputation of Ray Eames. Charles was a charismatic leader, brimming with ideas, who acted as the congenial spokesman for the company. With Ray Eames’ acquiescence, he sometimes took credit for achievements that he could not have wrought without his wife. The curators, led by the project director, Donald Albrecht of the Library of Congress, believe that Ray, an accomplished artist, played a greater role in the work, especially the fashioning of new furniture, than had been suspected.

Charles was born in St. Louis in 1907 and studied and practiced architecture before joining the faculty of the Cranbrook Academy of Art in Bloomfield Hills, Mich., just before World War II. Ray (whose full, maiden name was Bernice Alexandra Kaiser) was born in Sacramento in 1912. An abstract painter, she met Charles Eames when she attended classes at Cranbrook.

The couple married in 1941 and moved to Los Angeles, where Charles designed sets for Metro-Goldwyn-Mayer. In a few years, according to Albrecht, “Los Angeles and Southern California came to represent the American Dream to the world, proposing radical new ways of living, from patio homes to decentralized freeway cities.” The Eameses’ projects would reflect this expansive mood.

Looking for designs that were modern, functional and inexpensive, they tried to create a chair out of a single piece of plywood but had to settle on two pieces, one for the back and one for the seat. They did succeed in making chairs out of a single, curving form of fiberglass-reinforced plastic. Eames chairs, made out of plywood, plastic, wire mesh or aluminum, have dominated American offices and living rooms ever since.

Among scores of different pieces of furniture, Charles and Ray created a rather narrow, aluminum chaise lounge chair for their friend director Billy Wilder. Wilder, according to Charles, wanted “something he could take a nap on in his office but that wouldn’t be mistaken for a casting couch.” When he received it, Wilder told Charles that the chair “was absolutely wonderful . . . if you have a girlfriend that is built like a Giacometti.”

The Eameses built their Pacific Palisades home (with an adjoining studio) in 1949 out of mass-produced steel and glass. The house had been commissioned by Art & Architecture as part of a series of modern homes that the magazine believed would become a model for inexpensive postwar housing. After flirting with Modernism for a few years, however, most Americans preferred more traditional housing.

But the house impressed architects. The renowned British architect Norman Foster says the house “changed the way generations of architects and designers would think and look. . . . It certainly had that effect on me.” Although the house was clearly a permanent building, Foster told the curators of the exhibition, “you had the feeling that it could be packed away as easily as it seemed to have been assembled.”

Paul Goldberger, architecture critic for the New Yorker, puts the Eames house “on the short list of great houses designed by architects for themselves.” The august company includes Thomas Jefferson’s Monticello and Frank Lloyd Wright’s two Taliesins.

The Eameses later turned to education, turning out books and films and exhibitions that often described new developments in science. This work was commissioned both by private corporations and the U.S. government.

Their best-known film, “Glimpses of the U.S.A.,” was made for the 1959 American National Exhibition in Moscow, the site of the historic “kitchen debate” in which Vice President Richard Nixon and Soviet Premier Nikita Khrushchev, standing in a model of an American kitchen, argued vociferously about the benefits of capitalism and communism.

In their 12-minute movie, the Eameses projected 2,200 different images of Americans and their shopping malls, freeways, factories, farms and homes on seven giant 20-by-30-foot screens. The projection is repeated on small screens in the Library of Congress exhibition, and a visitor 40 years later is struck that, while the film has touches of diversity, it offers no hint of poverty. Yet a friend like Wilder recalls that Charles and Ray Eames were regarded as “very, very liberal” in their time. Optimism ruled their vision.

“The Work of Charles and Ray Eames: A Legacy of Invention,” continues through Sept. 4 at the Thomas Jefferson Building of the Library of Congress. Open Monday-Saturday, 10 a.m.-5 p.m. Closed Sundays and federal holidays. Public information: (202) 707-4604.