Thank you for your comment. I have tried this before. But it didn't solve my problem. I want the opener has a real reload, but each time the page is cached, which only has old information, not the most updated one that I want to see. I also tried the following code cited on the manual:
header ("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); // Date in the past
header ("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
// always modified
header ("Cache-Control: no-cache, must-revalidate"); // HTTP/1.1
header ("Pragma: no-cache");
but it still didn't work. Any idea?