A head-mounted augmented reality device for displaying an augmented reality display to a user viewing a real scene, the device comprising: (a) a pair of optical modules including a right optical module for a right eye of the user and a left optical module of a left eye of the user, each of said optical modules comprising a collimating display source optically coupled to a light guide, said light guide being at least partially transparent and being configured to guide image illumination projected by said collimating display source to a coupling-out region, and to couple out at least some of said image illumination from said coupling-out region towards an eye of the user; (b) a support structure configured to engage a head of the user so as to be supported by the head of the user; and (c) an optical bench comprising: (i) a first set of alignment features for aligning and affixing said right optical module, (ii) a second set of alignment features for aligning and affixing said left optical module, and (iii) a suspension arrangement for suspending said optical bench relative to said support structure, wherein said optical bench provides the sole mechanical connection between said pair of optical modules and said support structure; characterized in that: each of said first and second sets of alignment features comprises at least one planar alignment surface and at least two locating features for locating known reference locations of said optical module relative to said at least one planar alignment surface; wherein said at least two locating features are selected from the group consisting of: a pin for engaging an alignment aperture of said optical module, and an alignment aperture for receiving a pin; and said at least two locating features of the first set of alignment features and the second set of alignment features are configured to provide one degree of freedom for adjustment of an interpupillary distance between said coupling-out regions of said optical modules. (a) a pair of optical modules including a right optical module for a right eye of the user and a left optical module of a left eye of the user, each of said optical modules comprising a collimating display source optically coupled to a light guide, said light guide being at least partially transparent and being configured to guide image illumination projected by said collimating display source to a coupling-out region, and to couple out at least some of said image illumination from said coupling-out region towards an eye of the user; (b) a support structure configured to engage a head of the user so as to be supported by the head of the user; and (c) an optical bench comprising: (i) a first set of alignment features for aligning and affixing said right optical module, (ii) a second set of alignment features for aligning and affixing said left optical module, and (iii) a suspension arrangement for suspending said optical bench relative to said support structure, wherein said optical bench provides the sole mechanical connection between said pair of optical modules and said support structure; characterized in that: each of said first and second sets of alignment features comprises at least one planar alignment surface and at least two locating features for locating known reference locations of said optical module relative to said at least one planar alignment surface; wherein said at least two locating features are selected from the group consisting of: a pin for engaging an alignment aperture of said optical module, and an alignment aperture for receiving a pin; and said at least two locating features of the first set of alignment features and the second set of alignment features are configured to provide one degree of freedom for adjustment of an interpupillary distance between said coupling-out regions of said optical modules. (i) a first set of alignment features for aligning and affixing said right optical module, (ii) a second set of alignment features for aligning and affixing said left optical module, and (iii) a suspension arrangement for suspending said optical bench relative to said support structure, wherein said optical bench provides the sole mechanical connection between said pair of optical modules and said support structure; each of said first and second sets of alignment features comprises at least one planar alignment surface and at least two locating features for locating known reference locations of said optical module relative to said at least one planar alignment surface; wherein said at least two locating features are selected from the group consisting of: a pin for engaging an alignment aperture of said optical module, and an alignment aperture for receiving a pin; and said at least two locating features of the first set of alignment features and the second set of alignment features are configured to provide one degree of freedom for adjustment of an interpupillary distance between said coupling-out regions of said optical modules.