Introduction to Flat-Field Apochromatic Objectives and Monochromatic Objectives
Achromatic objective lens is a common type of objective lens (Table 1-1), which consists of several sets of positive and negative lenses with different surface radii
Mirror composition can only correct the axial chromatic aberration of red and blue light in spectral lines. Simultaneously correcting the on axis spherical aberration and near axis point aberration, this objective lens cannot
Eliminating secondary spectra, only correcting spherical aberration and chromatic aberration in the yellow and green wave regions, without eliminating residual chromatic aberration and spherical aberration and chromatic aberration in other wave regions, and resembling field bends
The curvature is still very large, which means that only a clear image in the middle range of the field of view can be obtained. When using, it is advisable to use yellow green light as the illumination source or insert it in the optical path
Yellow green filter. This type of objective lens has a simple structure, is economical and practical, and is often used in conjunction with Fukun eyepieces and corrective eyepieces. It is widely used in various fields
On a low magnification microscope. When taking black and white photos, a green filter can be used to reduce residual axial chromatic aberration and obtain photos with good contrast.
2. The apochromatic objective is composed of multiple advanced lens groups made of special optical glass and fluorite. Red, blue
Yellow light corrects axial chromatic aberration and eliminates secondary spectra, resulting in good image quality. However, with multiple lenses, processing and calibration are difficult. The correction of color difference
All wave regions of visible light. If blue or yellow filters are added, the effect will be better. It is the best objective lens in microscopes, capable of detecting spherical aberration and chromatic aberration
Has good calibration and is suitable for high magnification. But it still needs to be used in conjunction with a compensating eyepiece to eliminate residual color difference.
A planar chromatic objective lens adopts a complex optical structure of multiple lens combinations, which effectively corrects image dispersion and field curvature,
Make the entire field of view clear and suitable for microscopic photography. The correction of spherical aberration and chromatic aberration by this objective lens is still limited to the yellow green wave region, and there are still residual errors
Color difference.
4. The level of aberration correction for a planar apochromatic objective (PF) is comparable to that of apochromatic lenses, except for further correction of field curvature
The differential objective lens is the same, making the image clear and flat; But the structure is complex and difficult to manufacture.
Half achromatic objective lenses, also known as fluorite lenses, have lenses made of fluorite and perform better than achromatic lenses,
The price is cheaper than that of apochromatic lenses. The degree of aberration correction is between that of achromatic and apochromatic objectives, but other optical properties are similar to the latter
close; Low price, preferably used in conjunction with compensating eyepieces
