<script>
   var photoarray = [];
   var ajaxRequest = $.ajax
        ({
          url : "fhs_get_photos.php",
          type: "POST",
          dataType: "json",
          success: function(photo_array)
           {
              photoarray = photo_array;
            //line below works. the file name is correct but disappears
            //outside of this function
           console.log("photoarray[0][file_name] is: " + photoarray[0]['file_name']);
           },

          error: function(request, status, error)
           {
              alert('An error occurred: ' );
           }
        });

// in fhs_get_photos.php
    // SELECT * FROM table......
   echo $json = json_encode($result);
   return $json;

<h3>Welcome to the Historical Society's historical photo archive
    </h3>
    </header>
    <figure id="photo_figure">
        <script>
        //line below gets me: SCRIPT5007: Unable to get property 'thumb' of
        //undefined or null reference
        console.log("photoarray thumb: ") + photoarray[0]['thumb'];
        </script>