Abstract: An optical position measuring system (e.g., an interferometer) includes a superluminescent device (SLD) (e.g., a laser diode having at least one antireflective coated surface) and a detector. The SLD generates a light beam having a short coherence length (e.g., about 0.1 mm to about 0.5 mm, less than the optical path length of an optical element, and/or less than a spacing between optical elements). Through use of the short coherence length light beam, interference effects from spurious or ghost reflections that exist in conventional position measuring systems are substantially reduced or eliminated.

Abstract: This invention relates to trailer hitches generally and more specifically to a hitch that may be swiveled and extended as necessary to couple a trailer thereto and readily align and lock the hitch in transportation mode. The hitch has a base plate with a partial semicircular perimeter having a trunnion formed at its center of radius, a tubular housing secured at the trunnion atop the base plate to permit arcuate movement relative to the base plate, and tubular housing having a safety member thereunder which protrudes beneath the semicircular perimeter to limit relative vertical movement between the tubular housing and the base plate, a slide bar captured within said tubular housing with a towing ball projecting beyond said housing for limited linear movement therein, and a spring biased locking pin for releasable securing the trailer hitch with the slide bar retracted and the tubular housing centered along the perimeter.

Abstract: This invention relates to trailer hitches generally and more specifically to a hitch that may be swiveled and extended as necessary to couple a trailer thereto and readily align and lock the hitch in transportation mode. The hitch has a base plate with a partial semicircular perimeter having a trunnion formed at its center of radius, a tubular housing secured at the trunnion atop the base plate to permit arcuate movement relative to the base plate, and tubular housing having a safety member thereunder which protrudes beneath the semicircular perimeter to limit relative vertical movement between the tubular housing and the base plate, a slide bar captured within said tubular housing with a towing ball projecting beyond said housing for limited linear movement therein, and a spring biased locking pin for releasable securing the trailer hitch with the slide bar retracted and the tubular housing centered along the perimeter.