Guidelines for the Selection of Microscope Objectives
Microscope objective lenses are available in a rich variety of types and functions. The following is a brief introduction to how to select different types of objective lenses for a microscope.
First, there are three basic types of objective lenses: PLN (plan achromat), UPLFLN (universal semi-apochromat), and UPLSAPO (universal apochromat). There are also dedicated objective lenses for phase contrast, such as PLN-PH, UPLFLN-PH, and UPLSAPO-PH; objective lenses for differential interference contrast (DIC), such as PLN-P and UPLFLN-P; and long-working-distance objective lenses for inverted microscopes, such as LUCPLFLN and CFLN.
The main parameters describing an objective lens include magnification, numerical aperture (NA), working distance (WD), and field number (FN). For objectives with the same magnification, the reference parameters may vary depending on the type.
In general, observation methods for optical microscopes include bright-field (BF), dark-field (DF), phase contrast (PH), polarized light (PO), differential interference contrast (DIC), fluorescence (FL)-including blue, green, and red fluorescence-and ultraviolet fluorescence observation (UVFL). Different objective lens types are applicable to some of these observation methods. For example, the PLN (F.N. = 22) type objective lens can be used for the following observation methods: BF, DF, PH, PO, DIC, FL.
In addition to the objective lens itself, the overall optical system of a microscope and different models must be properly matched to achieve ideal observation results and maximize the performance of objective lenses.
