Electronic and optical communications instruments and components, namely, communication link testers for testing communication links; Calibration devices for calibrating ultrasonic testers, optical emission spectrometers; Calibration blocks for calibrating ultrasonic testers, optical emission spectrometers; Scanning electron microscopes; Microscopes and parts thereof, namely, lens, diaphragm or Iris, tube, arm, base, illuminator, stage, revolving nosepiece or turret; Microscopes, including st...