The advantage of the fiber optic bundles is that they can snake all over the place to get the light on the specimen. Fiber optic glass absorbs large amount of infra-red spectrum light. This makes the light at the end of the bundle cool. These illuminators are great for heat sensitive specimens. Since the illuminator is well away from the specimen the heat from the lamp will not hurt the specimen.
Fiber bundles come in flexible, goose neck and ring light forms.
The flexible bundles can be run from the light source to the specimen with the ease of placing an electrical cord. There are stands to hold the flexible fiber bundle and adjust it to suit your needs. They can be bent to point were ever they are needed. Two of these attached to an light source is called a bifucated fiber optic system. This is the most popular type of fiber optic illuminator.