private void optoelectronicClick(object sender, RoutedEventArgs e)
 {
     if (optoelectronicp == null)
     {
         OptoelectronicPage p = new OptoelectronicPage();
         optoelectronicp = p;
     }
     content.Content = optoelectronicp;
     CurrentControl  = content;
 }
        private void optoelectronicClick(object sender, RoutedEventArgs e)
        {
            OptoelectronicPage p = new OptoelectronicPage();

            content.Content = p;
        }