The enthusiastic introduction of laser light techniques into the area of particle field diagnostics has prompted the further development of increasingly sophisticated instrumentation. Laser light scatter methods offer online, in situ, nonintrusive evaluation of droplet and particle fields. Recent advances in this area have greatly extended the range of applications. Holographic techniques allow in-depth analysis of particle field phenomena never previously available. These optical techniques have been proven successful in applications ranging from spray diagnostics to combustion studies with numerous additional applications only now being considered.