FIGS. 1A-10 illustrate a multi-pass system 100 for efficiently generating LSP plasma, in accordance with one or more embodiment of the present disclosure. In one embodiment, as shown in FIG. 1A, the system 100 includes pump source 104 (e.g., one or more lasers) configured to generate a beam 101 of pumping illumination for sustaining plasma 106. The pump beam 101 is suitable for sustaining a plasma 106 within a volume of gas 107. The plasma 106, in response to the optical pumping from the pump beam 101, emits broadband radiation 115. In another embodiment, the system 100 includes a multi-pass optical assembly 102. In one embodiment, the multi-pass optical assembly 102 includes one or more optical elements 110a-110f configured to perform multiple passes 108a-108d of the pumping beam through a portion of gas 107 to sustain the plasma 106. In another embodiment, the one or more optical elements 110a-110f are arranged to collect an unabsorbed portion of the pumping beam transmitted through the plasma 106 and direct the collected unabsorbed portion of the pumping beam back into the plasma 106 and/or gas 107 near the plasma 106. As noted previously herein, the multi-pass optical assembly 102 is particularly useful in low pressure settings where the absorption of pump illumination by the plasma 106 is small. The one or more optical elements 110a-110f of the multi-pass assembly 102 provide for the “recycling” of the pump illumination, whereby the unabsorbed portion of the pump beam redirects the unabsorbed pump beam and back into to the plasma 106 and/or the gas 107 proximate to the plasma 106.