If you already have a IRC client installed on your system, you should be able to use this URL to access the channel: irc://chat.freenode.net/#opticks. Some of the popular and free IRC clients include: Visual IRC and ChatZilla.
If you don't want to download a client, you have two choices:
- You can use a free Java applet which allows you to join a freenode channel. If you go to http://java.freenode.net/index.php?channel=opticks, we have automatically filled in our channel name, #opticks and you only need to enter you desired nickname to join the chat session.
- You can go to mibbit. Mibbit is a completely web-based IRC client. It will work even if you have firewall restrictions and does not require any plug-ins be installed in your web-browser.