An optical reader for reading indicia such as bar codes comprises a first and second light source for generating first and second laser beams. The respective laser sources generate light at different wavelengths and a dichroic filter is provided to allow either source to be used without parallax effects....http://www.google.co.uk/patents/US5912451?utm_source=gb-gplus-sharePatent US5912451 - Moving beam and field of view readers with dichroic filter
