Catching generated by server report-file in IE

Need some help with Autoit + IE9
There is a one site in my network. That site have a button with pdf icon on it. After mouse click - server will use inner function to generate a pdf report and IE download window will appear. How can i catch this file using autoit and escape IE "save as" window?

Button info from DebugBar:

<IMG title="Save as PDF" onclick="prj.saveReportAs('table1.rdl', 'pdf', 'Report File', getParamsXml())" src="img/icon/pdf.gif" width=16 height=16>

I can't use InetGet because i don't have a direct link to file.