Use HTML meta tags to turn off browser caching.

<meta http-equiv="cache-control" content="max-age=0">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="expires" content="tue, 01 jan 1980 1:00:00 gmt">
<meta http-equiv="pragma" content="no-cache">