I am not sure how your code and logic goes. But Your issue should be solved with help of javascript, thats what my understanding is. so see below piece of code, and get some idea from it. Kindly excuse if it doesnt resolves.

function pop_up() {
    var win = window.open("", "new_window", 
                          "status=1,resizable=1,scrollbars=1,width=510
+,height=418");
    win.location = "code.pl?rm=display_excel";
    win.focus();
}
[download]

Kindly change the attributes and its values accordingly.