AT FIRST SIGHT, Lucinda Childs looks like a combination Joan of Arc and Vogue cover, part warrior-saint, part model.Her translucent, milky skin is stretched taut over a face of sharply molded planes, ledges and hollows, at once totally revealing and shut tight in an inviolable secrecy. The haute couture look comes from the classicism of the features, coupled with a lean lanky figure of sleek lines and elongated elegance. The sense of militant fervor is communicated mostly by the eyes, which pinpoint their focus like a lance on target.

In fact, Childs is neither saint nor manikin but a dancer and choreographer, one of the original members of the near-legendary Judson Dance Theater and one of its most adventurous survivors. With the Lucinda Childs Dance Company, which she founded and directs, she will be in the Washington spotlight this week performing the collaborative opus called "Dance" at Lisner Theater Thursday and Friday evenings, marking the climactic finale of the 9th Street Crossings festival. If she dwells on her physical appearance, it's because the mere sight of her on stage is instantly and absolutely transfixing -- she's one of those performers who makes you feel from the outset that it's not really necessary for her to do anything other than stand there to hold you rapt over a long span of time. In fact, however, when she begins to move, with an uncanny mixture of airy fluency and surgical precision, you know she was born to dance and to be seen dancing.

The name "Judson" by now has acquired the force of mystique in dance circles. Yet the cadre of artists who gathered at the Judson Memorial Church in Greenwich Village in the early '60s, shattering the canons of the past and initiating a new era in dance and other media, is now widely dispersed. Although the Judson radicals greatly altered contemporary conceptions of dance and dancing, very little of the work from those days has remained in circulation, and still less has found its way to a broader dance public. Childs is one of the few who has gone on to build solidly on her Judson foundations and carry her original insights into even more audacious terrain.

From the anarchic turmoil of the Judson era, Childs was to fashion a dance art of meticulously chiseled, crystalline surfaces and classically spartan forms, evolving from work with the troupe she founded in 1973 and which has since toured widely both here and abroad. In 1976, she found herself with a measure of unaccustomed celebrity as the choreographer and dance soloist of Robert Wilson's stunning, symbolic "opera," "Einstein on The Beach," given in two sold-out performances at the Metropolitan Opera. The composer of "Einstein" was Philip Glass, one of the master exponents of the new genre of "pulse" or "trance" music. Earlier this year, Childs and Glass presented their "Mad Rush" at the Paris Opera. Between "Einstein" and "Mad Rush," Childs, Glass and a new collaborator -- artist Sol Le Witt -- devised the opus called "Dance," premiered in 1979 and shortly to be seen at Lisner.

"Philip and I discussed the work originally in 1976 while working on "Einstein,'" Childs says."Jokingly we told each other it'd probably take two or three years . . . In the fall of '77, Philip and I met again, agreed that if we were serious we'd better start, and very generally discussed the structure of the work-to-be, which we planned as having five 20-minute sections with no intermission. The alternation between ensemble and solo sections was partly dictated by this structure -- no intermission meant a need for dancers to relieve each other. By the summer of '78, he showed me the score for the first solo section, and we talked about various artists, settling finally on Sol, who we thought would be particularly sympathetic to the project. He was enthusiastic, but vauge about what he'd do, except to say he wasn't interested in conventional decor."

It turned out Le Witt's contribution was to be a film, images of Childs and her dancers executing the same choreography that was to be performed live on stage, and projected on a transparent screen in front of them. The extraordinary multidimensional effect of this juxtaposition, with live and filmed dancers apparently occupying the same space, has to be seen to be appreciated, but it was the final touch that made the production of "Dance" a landmark of recent terpsichorean history.

All three collaborating artists, despite the differences of their domains, share a strong conceptual affinity -- each of them operates with lengthy repetitions of modular units into which barely perceptible modifications are introduced at a very slow pace. "I love having change come up on you gradually, "Childs says, "all foggy and misty over a long period of time." Speaking about the challenge of the collaboration and his colleagues' similarity of approach, composer Glass said at a recent Smithsonian symposium on the subject that "we had to transcend our own compatibility -- we knew we could reinforce each other, but there was also the danger of canceling each other out." In effect, the interaction of the elements -- music, dance and film -- takes on a sort of Rubik's-cube fascination. In actual working out, the creative process was a "chain reaction," Childs says, "from Philip, through me, to Sol; the music is the backbone of the piece, it's what holds it all together."

In choregraphing for "Einstein," Childs had made "scores" of Glass' music -- basic rhythmic skeletons from which she and her dancers could master the all-important, intricately fluctuating metrical patterns. She applied this procedure again in "Dance," later on drafting her own dance scores, which map out the corresponding flow of movement in space and time in exquisite linear plottings. Afterwards, Le Witt, working from both Glass' music and Childs' notations, prepared "story boards" for his filming. All these graphic compositional tools turn out to have considerable aesthetic rewards of their own -- a sampling of them is on exhibit at Washington Project for the Arts through Nov. 7, in conjunction with 9th Street Crossings.

A talent for drawing was not Childs' only artistic gift besides dance -- as a child, she had visions of theatrical stardom. Born in 1940 in New York City to a doctor father and an arts-loving mother, she had conceived a feverish ambition to become an actress by the time she was 10, and did endless school plays. She was steered toward dance by an acting teacher who thought it would help her stage presence -- as a teenager she was, by her own description, "clumsy, shapeless and on the heavy side." There followed, after school, during summers and at Sarah Lawrence College, a series of propelling encounters with major dance figures, including Hanya Holm, Helen Tamiris, Merce Cunningham and finally Yvonne Rainer, who "blew the top off the tea kettle" and asked Childs to join the newly formed Judson Dance Theater in 1963. Curiously, all through the Judson period and afterwards, she attended ballet class (mostly with Mia Slavenska); in a passing reference recently, she called Mikhail Baryshnikov "the most gorgeous dancer in the world."

The Brooklyn Academy of Music, scene of the American premiere of "Dance," will be the site of the first domestic performance of her most recent work, "Relative Calm," which has music by Jon Gibson and decor by Robert Wilson and was commissioned for the Paris Festival d'Automne this fall. But in the meantime, her youthful dreams of acting have come home to roost. This past summer she was cast in a lead role in a feature film by South American director Marie Jimenez, and the picture, "Jeanne d'Iman," has since been shown at a number of European festivals. "I play the part of a classical pianist who switches to a night club where she gets involved with a number of people who float in and out of the bar," says Childs. This latest career development, however, doesn't necessarily signify a reversion to drama. "I'd like to keep dancing for a while -- the truth is, I feel I must dance, even if eventually it isn't on stage.