fresnel lens中文

The depth of field depends inversely on the numerical aperture of the lens, i.e. for a strong lens the depth of field is quite small.

Fresnel light

Lenses with lower magnification (eg 4x, 10x) have a greater depth of field than lenses with higher magnification (eg 40x, 60x, 100x). Depth of field can be increased by zooming in or lowering the position of the condenser. Thus, details and impurities lying above and below the object can be displayed. On the contrary, we achieve a decrease in the depth of field as the aperture of the lens increases.

Using a Fresnel Lens to start a campfire is easy; all you need is dry tinder, sunlight and a bit of practice. As with all fire starting methods, using the right tinder is essential. To learn more about how to get the most out of your Fresnel Lens, check out our blog article, Why Everyone Needs a Fresnel Lens.

Fresnellens

A Fresnel Lens is one of the most practical items you can carry with you in the wilderness and beyond. It weighs next to nothing yet is powerful enough to ignite tinder, create a bright beam of light for attracting attention, or magnify small details on maps, plants or insects. You can even use it to perform tasks that require precision, like repairing gear or removing a splinter.

Weighing just 4.5g with 3x magnification, our ultralight Fresnel Lens is capable of focusing the sunlight into an intense point that is powerful enough to start a fire within seconds.

When viewing the transparent preparation, we make a cut through the preparation, we can clearly observe only a thin layer. We are talking about„the optical section“. The microscope will clearly show us the structures that lie in it. So focusing is actually just the localization of object structures, or the entire observed object into this layer. By turning the micrometric screw, which allows us to focus on the given object, we pass a series of consecutive optical sections through the observed object.

By the depth of field of the microscope we mean the thickness of the layer of the preparation in which the sharply displayed objects are located. The depth or thickness of such a layer of the object indicates the depth of field, or depth of field (penetration ability i.e. "ability to draw sharply in depth") of the lens. Objects that lie above and below this layer are seen out of focus or are not visible at all.