Hi I'm completely stumped, can someone help please?

The below code executes without errors in chrome and firefox but the alert returns 'undefined' even though images[] is populated correctly with string paths when I test from the browser consoles.
can anyone see the problem?

1. <script type="text/javascript">
   var images = new Array();
   $(document).ready(function() {
     $.getJSON("images/research/getImgs.php", function(json){
       for(var i=0;i<json.length;i++) {
         images[i] = json[i];
       }
     });
     alert(images[1]);
     $('#slideshow').attr("src", images[1]);
   });
   
   </script>
   
   
   
   
   
   
   
   
   
   
   
   

many thanks
Tim