An auxiliary lens (also called a “Barlow” lens or "objective" lens, though this should be distinguished from the built-in objective lens that comes with the microscope) is used to increase or decrease the total magnification of a microscope, or increase or decrease its working distance. A stereomicroscope with a 2x built-in objective lens and 10x eyepieces, for example, would have a total magnification of 20x, but if you needed more than that you could attach a 1.5x auxiliary lens to achieve 30x.
Auxiliary lenses also cause a corresponding increase or decrease in working distance. Mounting a lens that increases total magnification would result in a shorter working distance, while mounting one that decreases magnification would result in a longer working distance. The latter can be helpful for users who need more room for instruments or tools between the specimen and objective lens.
Below are some things to consider when using an auxiliary lens:
An auxiliary lens (also called a “Barlow” lens or "objective" lens, though this should be distinguished from the built-in objective lens that comes with the microscope) is used to increase or decrease the total magnification of a microscope, or increase or decrease its working distance. A stereomicroscope with a 2x built-in objective lens and 10x eyepieces, for example, would have a total magnification of 20x, but if you needed more than that you could attach a 1.5x auxiliary lens to achieve 30x.
Auxiliary lenses also cause a corresponding increase or decrease in working distance. Mounting a lens that increases total magnification would result in a shorter working distance, while mounting one that decreases magnification would result in a longer working distance. The latter can be helpful for users who need more room for instruments or tools between the specimen and objective lens.
Below are some things to consider when using an auxiliary lens: