Abstract: There is provided a LCOS panel assembly of a projection system comprising: a LCOS panel; a panel support supporting the LCOS panel and coupled to the quad side; a quarter-wave plate provided at the front side of the LCOS panel to polarize light; a quarter-wave plate holder rotatably supported about the panel support at a state where the quarter-wave plate is coupled thereto; and adhesives interposed on a contact surface of the quarter-wave plate holder and the panel support, so that foreign substance is prevented from being injected on a optical path of the LCOS panel assembly of the projection system or image matching is prevented from being deteriorated.