If the electronic file is a PDF and you are using Web Access 9.2, the following URL format should work:
http://ServerName/laserfiche/index.aspx?db=RepoName#id=EntryId
This will open the PDF file in a new tab. Note that this new tab will just have the PDF, not the metadata, text, or annotations.
For other electronic document types (.doc, .xlsx, etc.), opening the electronic file in the browser is not supported. Viewing PDFS in a new tab is also not support prior to WA 9.2.
You can, however, view the Laserfiche image pages, text pages, and metadata by going to a URL like the following:
http://ServerName/laserfiche/index.aspx?db=RepoName#id=EntryId;view=pages