Alone onstage Luc Houtkamp pushes at the edges of even postfreedom lyricism, as he painstakingly investigates the gamut of sounds uniquely possible on the tenor saxophone. This is sonic exploration stuff, reminiscent of Roscoe Mitchell's rigorous a cappella exploration of previously unclaimed badlands on the saxophone landscape. (Many tenor players, for example, work the "flute tones" of their instrument, manipulating the notes just above the written range of the saxophone into an entire extra octave; Houtkamp takes this a step further to create a viable octave in the piccolo range--a startling, and ethereally lovely, effect.) A lot of Houtkamp's pieces take the form of etudes, each of which, like the classical etudes of centuries past, pinpoints and dissects a particular technique or strategy. Houtkamp doesn't go out of his way to camouflage this: he quite clearly targets the subject of split-tone multiphonics on one piece, the rhythmic potential of slap-tongue articulation on another, the variety arising from a strictly controlled approach to phrasing on yet a third. But the fact that each piece so baldly pursues solutions to a given musical problem doesn't spoil its artistic value--like the etude writers of the past, Houtkamp challenges himself to make these "exercises" highly musical. Spontaneity is not the first order: Houtkamp remains more concerned with honing these pieces into precise expositions than with trying to uncover new truths in each improvisation. He does use improvisation--but primarily to develop a composition in rehearsal before he presents it publicly as a more or less finished piece. "This isn't new," Houtkamp explained several years ago. "In fact, Johnny Hodges played the same solo, year in and year out, in certain pieces with Duke Ellington. These solos were originally improvised but slowly acquired a fixed form, with little variation." Nonetheless, the sheer complexity of Houtkamp's technique and conception belies the comparison, as he flirts dazzlingly with the outer limits of modern saxophonics. Saturday, 10:30 PM, Lunar Cabaret and Full Moon Cafe, 2827 N. Lincoln; 327-6666.