Abstract: An adjustable height table includes a base frame, a slider frame assembly, a generally planar support surface and a lifting mechanism. The main portion of the base frame is formed by welding three tubular components to form an H-shape. Each of the end portions of the H-shape include a mounting to support a swiveling locking castor. Above each castor there extends from the H-shaped main portion, a vertically extending tubular post. The slider frame assembly also includes an H-shaped main portion formed of three tubular members. Four vertically extending hollow tubular column members are attached to the H-frame so that they may telescopingly engage the four vertically extending posts of the base frame. A generally planar support surface is attached to the top of the four vertically extending columns located on the slider frame. Located between the central tube of the H portion of the base frame and central tube of the slider frame assembly, there is located a lifting mechanism, preferably a hydraulic jack.

Abstract: An optical instrument for facilitating the observation of surface engravings located on an optical lens includes a base housing having a light source therein for illuminating the optical lens. An image contrastor, selected based on the type of lens to be examined, is placed on the base housing over the light source. The image contrastor includes its own housing within which is positioned a viewing plate and a light diffuser. A screening pattern or coating is formed on the viewing plate to define a backdrop for examining the lens. A support member extends from the base housing and carries a magnifying lens. With this arrangement, an optical lens may be placed between the image contrastor and the magnifying lens to enhance the observation of engravings on the optical lens.