THOUGH THE work of Czechoslovakia's best 20th-T century artists is only beginning to appear on the world stage, one fact is clear: There are world-class artists working in and around Prague, and we know far to little about them.

Thanks to the efforts of interested compatriots, group shows of contemporary Czech art have been turning up with increasing frequency in New York and Washington--most recently at Meridian House last month. Now the first solo show in America by one of the most intriguing and whimsical of these artists is on view at Robert Brown Contemporary Art.

Though little-known here, poet-playwright-painter Ladislav Novak is no newcomer to art. Now 57, and a teacher of the Czech language, he began his career at a most inauspicious time and place: the beginning of World War II in Trebic, Moravia (now Czechoslovakia)--the medieval town where he still lives. At the heart of that town was a Jewish ghetto--depopulated by the Nazis before the young artist's eyes. The emptied ghetto became for Novak a symbol of the poet's condition in our times: "A poet is also an exile," he has said, "and his place is not on the side of those who rejoice, but of those who weep."

In fact, there is more joy and wit than weeping in Novak's art, and though he has clearly taken sides in this world, it is not only with poets, but with everyone who feels things deeply.

In his teens, he also formed an early alliance with surrealism, which sought--through what was called "automatism"--to produce art that came straight from the untapped regions of the mind, bypassing logic and visual experience. Ever since, he has continued to mine his own rich, poetic imagination to produce works whose titles are as ephemeral and elusive as the themes they conjure: "Nietzsche's Visions: 6 January, 1889," and "To Hold the Whole Cosmos on the Tip of an Idea," are but two examples in the present show.

After experiments with collage, conceptual art and "earth art"--he once "painted" the surface of a frozen lake--Novak, in the '60s, developed his current medium, which he calls "froissage." These delicate watercolor fantasies are made by crumpling paper, straightening it out and washing the surface with diluted ink to bring out the random linear patternings formed by the creases. Among these lines, the artist hunts down hidden images, fixes them with a pen and fills them in with pale, delicious watercolor.

Thus have come forth figments such as "Test Image"--gray and pink turtle-shaped forms that zoom through space, and "Aerial Combat," in which paper-airplane shaped birds swoop playfully at each other. Other works express more personal feelings, such as "The Unhappy King (Just as Me)." As in the drawings of Paul Klee--which Novak's works often recall--the titles are an integral part of the visual poetry he creates. The show continues at Robert Brown, 1005 New Hampshire Ave. NW, near Washington Circle, through April. Hours are Thursdays through Saturdays, noon to six; Sundays 2 to 5. Otherwise by appointment.