A: Below the RMS mounting thread of the objective lens, there is a ring-shaped metal plane with a larger diameter. When the objective lens is screwed into the objective lens converter, the mechanical positioning is accomplished by the plane fitting the lower end surface of the converter, not by screwing it to the limit. The parfocal distance is measured from this flange step surface.
A: Standard mechanical distance from the objective flange step to the imaging plane of the sample. When all objective lenses of the same microscope have a unified 45mm parfocal distance, the rotating animal lens turntable switches the magnification, and only a small amount of fine-tuning can be done to maintain focus without significantly refocusing. The general standard for market metallographic and industrial microscopes is 45mm, and there are also 60mm and 95mm specifications, which cannot be mixed with each other.
A: It belongs to the parameters of the infinity optical system, indicating that the focal length of the matching Viewing tube lens is 200mm. The aberration correction of the objective lens and the system magnification are based on this barrel lens; the system magnification = the focal length of the barrel lens ÷ the focal length of the objective lens itself. Note that it should not be confused with the old limited 160mm mechanical cylinder length, and the 200mm objective lens cannot be used with the host of the 180mm cylinder lens, otherwise the magnification deviation and the edge of the picture will be blurred.
A: No. WD working distance: the distance between the front lens surface of the objective and the sample surface when clearly imaged. Parallel Focus Distance: The distance from the flange step face to the sample. The parfocal distance of 45mm must be greater than the WD working distance. The working distance of the high-power objective lens is very short, so be careful not to collide with the lens when using it; it is recommended to use a long working distance objective lens when observing a specimen with steps and with a clamp/hot table.
A: The numerical aperture NA determines the ability of the objective to distinguish tiny details. At the same magnification, the larger the NA value, the higher the resolution, and the brighter the image with more collected light; however, the larger the NA, the smaller the depth of field, and the higher the fluctuation of the sample, the more easily local blurred. Imaging clarity prioritizes NA, not just magnification. High magnification and low NA will only result in a blurred image that is magnified.
A: Not necessarily. Even if the RMS thread can be screwed into the converter, if the flange step position does not match, the parfocal distance will be disordered, and the switching objective will be in focus, while the aberration and magnification will also be affected by the focal length of the barrel lens, and the cross-system objective cannot be directly interchanged.
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