Objective lenses magnification

When an eyepiece is used, the total magnification should be the objective lens magnification multiplied by eyepiece magnification. 

The final set of magnetic lenses beneath the specimen are jointly referred to as post-specimen lenses. Their primary task is to magnify the signal transferred by the objective lens. Modern instruments typically contain four post-specimen lenses diffraction, intermediate, projector 1, and projector 2 (in, order of appearance below the specimen). They provide a TEM with its tremendous magnification flexibility. 

To adjust the lens to the object was so long and tedious a task that it is not surprising that Leeuwenhoek used an individual lens for each object. The magnification varied and at best did not exceed... 

Figure 12. (A) Relative magnification of metaphase cells under a low and a high objective lens (B) a partial chromosome spread under a low objective lens digitized in two grey-level and low resolution (C) the same partial chromosome spread under 10Ox objective (D) a chromosome spread digitized in 16 levels.

We have developed a novel ultrasensitive detection method, thermal lens microscopy (TLM), for nonfluorescent species [13]. TLM is photothermal spectroscopy under an optical microscope. Our thermal lens microscope (TLM) has a dual-beam configuration excitation and probe beams [13]. The wavelength of the excitation beam is selected to coincide with an absorption band of the target molecule and that of the probe beam is chosen to be where the sample solution (both solvent and solute) has no absorption. For example, in determination of methyl red dye in water, cyclohexane, and n-octanol, a 514-nm emission line of an argon-ion laser and a 633-nm emission line of a helium-neon laser were used as excitation and probe beams, respectively [21], Figure 4 shows the configuration and principle of TLM [13]. The excitation beam was modulated at 1 kHz by an optical chopper. After the beam diameters were expanded, the excitation and probe beams were made coaxial by a dichroic mirror just before they were introduced into an objective lens whose magnification and numerical aper-... 

The objective lens is the most important lens having the greatest impact on the image quality. Magnification depends on the focal length as discussed previously, hence. 

Figure 3.71. Optical system used for 3D microfabrication using TP initiated polymerization of a photopolymerizable composition. The numerical aperture of the objective lens is 0.85 (magnification of 40), the accuracy of the galvano-scanner set and the dc motor scanner were 0.3 and 0.5 pm, the beam power at peak in the photocrosslinkahle composition is about 3 kW, with a repetition rate of 76 MHz and a pulse width of 130 fs at a wavelength of 770 nm [76].

The working distance between the specimen and objective lens is determined by magnifications of the lens. Estimate the difference in the working distance for objective lens with power of 5 x, 20 x and 50 x. 

To obtain a 400 x magnification image we may choose a 40 x objective lens with a lOxprojector lens, or 20xobjective lens with a 20xprojector lens. What are the differences in their image quality ... 

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