Optical instrument and components thereof

An optical assembly for use with a spectrophotometer. The optical assembly may comprise an illumination source, a detection sensor, a monitor sensor, and an optical piece having a first side adapted to face a sample. The optical piece may define an illumination channel extending from the illumination source toward the first side. The optical piece may also define a detection channel extending from the first side toward the detection sensor. In addition, the optical piece may define a monitor channel extending from the illumination channel toward the monitor sensor. Also, a light emitting diode (LED) assembly for use with an optical measurement device. The LED assembly may comprise a substrate having a top surface and a bottom surface and a plurality of LED dies positioned on the substrate to emit light in a first direction normal to the bottom surface of the substrate. The LED assembly may also comprise a plurality of leads in electrical contact with the plurality of LED dies. The plurality of leads may be positioned on the bottom surface of the substrate, and may be configured to surface-mount to a board.