A device for inspecting microscopic objects. The nitride semiconductor structure mainly includes a stress control layer disposed between a light emitting layer and a p-type carrier blocking layer. A plurality of comparison and other metrics may be computed based on the computed plurality of parameters. The upper body portion and the lower body portions, when positioned in a disc space between the upper and lower vertebral bodies and affixed to a respective vertebral body at the flange portion, are independently movable relative to the other along complimentary bearing surfaces on each of the superior and inferior members.