An apparatus for room temperature laser bonding comprising: an x-axis motion stage mounted to a base; a y-axis motion stage mounted to the x-axis motion stage; a substrate alignment fixture mounted on the y-axis motion stage, said alignment fixture adapted to align and secure at least two substrates with a mutual interface as a workpiece, a gantry mounted to the base and supporting alignment optics for a laser to focus on the workpiece in the alignment fixture; and a controller for translation of the x-axis motion stage and y-axis motion stage for motion of the focused laser on the workpiece. the apparatus being characterised in that the substrate alignment fixture comprises: a mounting structure to mount the alignment fixture to the y-axis stage; a vertically translating engagement slider supported by translation rods extending from the mounting structure; a pneumatic expansion device positioned intermediate the engagement slider and the mounting structure for vertical adjustment of the engagement slider; a workpiece holding frame to support the workpiece; risers extending upward from the mounting structure to receive an optical flat to be positioned over the holding frame; a securing plate mounted with spacers to fix the optical flat to the risers; whereby, retraction of the pneumatic expansion device lowers the engagement slider allowing insertion of the holding frame into position on the engagement slider and inflation of the pneumatic expansion device urges the engagement slider and holding frame upward compressing the workpiece against the optical flat; an x-axis motion stage mounted to a base; a y-axis motion stage mounted to the x-axis motion stage; a substrate alignment fixture mounted on the y-axis motion stage, said alignment fixture adapted to align and secure at least two substrates with a mutual interface as a workpiece, a gantry mounted to the base and supporting alignment optics for a laser to focus on the workpiece in the alignment fixture; and a controller for translation of the x-axis motion stage and y-axis motion stage for motion of the focused laser on the workpiece. the apparatus being characterised in that the substrate alignment fixture comprises: a mounting structure to mount the alignment fixture to the y-axis stage; a vertically translating engagement slider supported by translation rods extending from the mounting structure; a pneumatic expansion device positioned intermediate the engagement slider and the mounting structure for vertical adjustment of the engagement slider; a workpiece holding frame to support the workpiece; risers extending upward from the mounting structure to receive an optical flat to be positioned over the holding frame; a securing plate mounted with spacers to fix the optical flat to the risers; whereby, retraction of the pneumatic expansion device lowers the engagement slider allowing insertion of the holding frame into position on the engagement slider and inflation of the pneumatic expansion device urges the engagement slider and holding frame upward compressing the workpiece against the optical flat; a mounting structure to mount the alignment fixture to the y-axis stage; a vertically translating engagement slider supported by translation rods extending from the mounting structure; a pneumatic expansion device positioned intermediate the engagement slider and the mounting structure for vertical adjustment of the engagement slider; a workpiece holding frame to support the workpiece; risers extending upward from the mounting structure to receive an optical flat to be positioned over the holding frame; a securing plate mounted with spacers to fix the optical flat to the risers; whereby, retraction of the pneumatic expansion device lowers the engagement slider allowing insertion of the holding frame into position on the engagement slider and inflation of the pneumatic expansion device urges the engagement slider and holding frame upward compressing the workpiece against the optical flat;