Focal lengthof lens formula

Note: this box searches only for keywords in the titles of articles, and for acronyms. For full-text searches on the whole website, use our search page.

Focal lengthof mirror formula

To avoid ambiguity, it is better to use the term absorbance, as far as absorption is the used attenuation mechanism. However, attenuation may also be achieved with reflection or scattering.

What isthe focal lengthof a lens Physics

The most important characteristic of a lens is its principal focal length, or its inverse which is called the lens strength or lens "power". Optometrists usually prescribe corrective lenses in terms of the lens power in diopters. The lens power is the inverse of the focal length in meters: the physical unit for lens power is 1/meter which is called diopter.

Here you can submit questions and comments. As far as they get accepted by the author, they will appear above this paragraph together with the author’s answer. The author will decide on acceptance based on certain criteria. Essentially, the issue must be of sufficiently broad interest.

The principal focal length of a lens is determined by the index of refraction of the glass, the radii of curvature of the surfaces, and the medium in which the lens resides. It can be calculated from the lens-maker's formula for thin lenses.

Focal lengthexamples

LASEROPTIK can provide coatings for variable optical attenuators. One can change the transmission by tilting an edge filter, with highest transmission at normal incidence and typical operation for angles of incidence between 0° and 45°.

For example, an optical density of 3 means that the optical power is attenuated by the factor 103 = 1000. That would correspond to an attenuation by 30 decibels.

Further, we have many interesting case studies on the same page, with topics mostly in fiber optics. Concrete examples cases, investigated quantatively, often give you much more insight!

Howtofind focal lengthof convex lens

Optogama designs and manufactures motorized laser power attenuators (LPA) for laser power control. LPA are available for use in the UV, visible, and NIR spectral ranges from 250 nm to 2000 nm. These devices feature a large clear aperture dedicated for considerable size beam applications. All optical elements of these laser power attenuators are made for high LIDT and provide a stable and reliable performance even when using them with high power lasers in industrial applications.

Using our advertising package, you can display your logo, further below your product description, and these will been seen by many photonics professionals.

Focal lengthcamera

Note: the article keyword search field and some other of the site's functionality would require Javascript, which however is turned off in your browser.

For a thin double convex lens, refraction acts to focus all parallel rays to a point referred to as the principal focal point. The distance from the lens to that point is the principal focal length f of the lens. For a double concave lens where the rays are diverged, the principal focal length is the distance at which the back-projected rays would come together and it is given a negative sign. The lens strength in diopters is defined as the inverse of the focal length in meters. For a thick lens made from spherical surfaces, the focal distance will differ for different rays, and this change is called spherical aberration. The focal length for different wavelengths will also differ slightly, and this is called chromatic aberration.

How do you find the focal lengthin physics

Optical densities depend on the optical wavelength, although that dependence may be weak, e.g. in neutral density filters.

Optical density may mean the absolute value of the logarithm with base 10 of the power transmission factor of an optical attenuator (e.g. as used for a laser safety glass):

What isfocal lengthof lens

A transparent medium is sometimes said to have a high optical density (or to be relatively dense) if it has a high refractive index. For example, one may say that total internal reflection is possible only if the beam comes from the optically more dense medium. That use of the term has nothing to do with attenuation.

Please do not enter personal data here. (See also our privacy declaration.) If you wish to receive personal feedback or consultancy from the author, please contact him, e.g. via e-mail.

By submitting the information, you give your consent to the potential publication of your inputs on our website according to our rules. (If you later retract your consent, we will delete those inputs.) As your inputs are first reviewed by the author, they may be published with some delay.

This shows parallel beams from two helium-neon lasers converging to the principal focal point of a 30 cm double convex lens. The rays then enter a diverging lens of focal length -10cm on the right. The laser beams were made visible with a spray can of artificial smoke.

If several attenuators are used in series, their optical densities can simply be added. That is the key advantage of using such a logarithmic quantity.

EKSMA Optics offers variable attenuators for linearly polarized laser beams with high performance optics. They are available for Nd host laser applications in the 1040–1070 nm range and for femtosecond applications with broadband Ti:sapphire and Yb:KGW/KYW laser pulses. Manual and motorized versions available, highly customizable and designed for use in laboratory settings. Compact motorized laser power attenuators provide stable and reliable performance even in high power lasers for industrial applications.