| Air | An imaging immersion condition in which no liquid or oil medium is used between the objective lens and the specimen or coverslip; the objective is separated from the sample only by air. | BAO:0150017 |
| Oil | An imaging immersion condition in which a specialized oil with a refractive index matched to glass is applied between the objective lens and the specimen or coverslip to increase numerical aperture and resolution. | BAO:0150019 |
| Water | An imaging immersion condition in which water is applied between the objective lens and the specimen or coverslip, commonly used with water-immersion objectives for live-cell or aqueous-sample imaging. | BAO:0150020 |
| Other | An imaging immersion medium other than air, oil, water, glycerol, or a multi-immersion configuration. | NCIT:C17649 |
| Multi | An imaging immersion condition using a multi-immersion objective lens compatible with more than one immersion medium (e.g., air, water, oil, or glycerol), allowing the same lens to be used across different sample preparations. | Not available |
| Glycerol | An imaging immersion condition in which glycerol, a triol with a refractive index intermediate between water and oil, is applied between the objective lens and the specimen; glycerol-immersion objectives are often used for tissue-clearing or deep-imaging applications. | CHEBI:17754 |