Abstract: Formulations for use as mounting media in microscopy and also useful as optical coupling materials for fibers and lens systems having a wide range of refractive index between 1.58 to 1.73 and exhibiting a range in viscosity from a very viscous fluid to a semi-solid resin or melt. The material is selected from brominated diphenyl oxides and modified or unmodified alpha-methylstyrene polymers. These materials can be employed individually or blended together with a stabilizer to provide a host of materials having different refractive indexes within said range and useful in various optical systems.

Abstract: A heavy mineral oil having a relatively high viscosity is employed as an immersion oil for use in fluorescence microscopy. The oil exhibits no auto fluorescent characteristics while exhibiting a compatible refractive index to allow the same to be used with condenser/objective lens systems in fluorescence microscopy.

Abstract: An immersion oil formulation for use in microscopy and related optical fields consists of a blend of a dialkyl phthalate, a butyl benzyl phthalate and chlorinated paraffin. The compounds, when blended, possess a desired optical property including a refractive index of 1.518 or thereabouts and an extremely low fluorescence enabling the immersion oil to be utilized in the field of fluorescence microscopy. The resultant blend also possesses a low toxicity and therefore eliminates all the disadvantages of prior art immersion oils which contain PCBs or which exhibit undesirably high auto fluorescence.