A compact lighting device or a strobe device includes a discharge tube; a prism unit having an incident surface receiving a light from said discharge tube and an outgoing surface that ejects an incident light to a side of an object to be photographed; and a first optical unit and a second optical unit...http://www.google.co.uk/patents/US6400905?utm_source=gb-gplus-sharePatent US6400905 - Lighting angle variable lighting device
