An end-effector for a surgical robot system, comprising: - an end-effector body configured to guide a surgical instrument; - a plurality of compressible O-rings configured to be seated in a plurality of corresponding complementary O-ring seats disposed in the end-effector body; - a mounting collar configured to be secured to the end-effector body; and - an optical sub-assembly (426, 526) coupled to the end-effector body, the optical sub-assembly (426, 526) comprising: - a housing coupled to the end-effector body, the housing comprising an engagement portion; - a window that is transparent to a predetermined range of light radiation wavelengths, the housing and the window forming a cavity; - a gasket disposed between the housing and the window, the gasket defining a gasket hole therethrough; - a cover portion disposed over the window and engaging the engagement portion of the housing, the cover portion compressing the gasket between the window and the housing to form a seal between the window and the housing, the cover portion defining a cover hole therethrough; and - a light emitter disposed in the cavity, the light emitter configured to emit light in the predetermined range of light radiation wavelengths through the gasket hole, the window, and the cover hole - wherein the end-effector body forms an interior portion including electronic components and the mounting collar, when secured to the end-effector body, is configured to compress the plurality of compressible O-rings into the corresponding O-ring seats thereby forming moisture-proof seals between the mounting collar and the body. - an end-effector body configured to guide a surgical instrument; - a plurality of compressible O-rings configured to be seated in a plurality of corresponding complementary O-ring seats disposed in the end-effector body; - a mounting collar configured to be secured to the end-effector body; and - an optical sub-assembly (426, 526) coupled to the end-effector body, the optical sub-assembly (426, 526) comprising: - a housing coupled to the end-effector body, the housing comprising an engagement portion; - a window that is transparent to a predetermined range of light radiation wavelengths, the housing and the window forming a cavity; - a gasket disposed between the housing and the window, the gasket defining a gasket hole therethrough; - a cover portion disposed over the window and engaging the engagement portion of the housing, the cover portion compressing the gasket between the window and the housing to form a seal between the window and the housing, the cover portion defining a cover hole therethrough; and - a light emitter disposed in the cavity, the light emitter configured to emit light in the predetermined range of light radiation wavelengths through the gasket hole, the window, and the cover hole - wherein the end-effector body forms an interior portion including electronic components and the mounting collar, when secured to the end-effector body, is configured to compress the plurality of compressible O-rings into the corresponding O-ring seats thereby forming moisture-proof seals between the mounting collar and the body. - a housing coupled to the end-effector body, the housing comprising an engagement portion; - a window that is transparent to a predetermined range of light radiation wavelengths, the housing and the window forming a cavity; - a gasket disposed between the housing and the window, the gasket defining a gasket hole therethrough; - a cover portion disposed over the window and engaging the engagement portion of the housing, the cover portion compressing the gasket between the window and the housing to form a seal between the window and the housing, the cover portion defining a cover hole therethrough; and - a light emitter disposed in the cavity, the light emitter configured to emit light in the predetermined range of light radiation wavelengths through the gasket hole, the window, and the cover hole - wherein the end-effector body forms an interior portion including electronic components and the mounting collar, when secured to the end-effector body, is configured to compress the plurality of compressible O-rings into the corresponding O-ring seats thereby forming moisture-proof seals between the mounting collar and the body.