Website: http://www.i-leos.org
To join: http://www.i-leos.org/info/membership_tab.asp

Website: http://www.aps.org
To join: http://www.aps.org/membership/join.cfm

Website: http://www.osa.org
To join: http://www.osa.org/join

Website: http://www.i-leos.org
To join: http://www.i-leos.org/info/membership_tab.asp

Website: http://www.osa.org
To join: http://www.osa.org/join