A beam modulator (14) for modulating a beam (20) includes a modulator element (26) and a housing assembly (24). The modulator element (26) is positioned in the path of the beam (20). The housing assembly (24) retains the modulator element (26). The housing assembly (24) can include a housing (234), a first retainer assembly (342), and a second retainer assembly (344). The first retainer assembly (342) flexibly secures the modulator element (26) to the housing (24) and the second retainer assembly (344) fixedly secures the modulator element (26) to the housing (234) with the modulator element (26) positioned between the retainer assemblies (342) (344). With this design, the retainer assemblies (342) (344) can cooperate to retain the modulator element (26) in a fashion that applies a substantially uniform and small pressure across the modulator element (26).
