Focal lengthof lens formula

It's basic geometry: you have a right angle triangle, with half the FOV as one of the angles (a), and half your image size as the opposite side (A). To calculate the focal length F, use tan(a) = A/F, which gives F = A/tan(a).

As your sensor size is given in pixels (assumed square pixels!), your focal length will also be in pixels. To get it in a more usual unit (m), you need to know the pixel size.

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What isfocal lengthof lens

There is a calculator that will do this at https://www.scantips.com/lights/fieldofview.html (Option 6). The geometry is shown at bottom of that page, however, you must use Trig for angles.

Calculate focal lengthfrom image

These polarizers may slightly diffuse the transmitted beam and are not recommended for imaging applications or applications that require the input divergence to be preserved. Similarly, they may not maintain the collimation of large input beams. The beam will walk as the polarizer rotates, so it is recommended to use these polarizers only when a single fixed polarization direction is needed. Rotation assemblies, like the one shown to the right, should be used only to set a fixed output angle.

Thorlabs' film polarizers are designed to linearly polarize low-power beams of light. Each film polarizer is a square that can be left whole or cut to custom sizes. The polarization axis is marked with an arrow and is aligned to the flat edge of the LPVISE2X2, while the polarization axis of the LPNIRE2X2 and LPNIRE11S is noted by a sticker. There is a protective film on both sides of each polarizer that must be removed prior to use.

To explore the available types, wavelength ranges, extinction ratios, transmission, and available sizes for each polarizer category, click More [+] in the appropriate row below.

What you need to know for field of view is the camera sensor size (or film size) measured in mm. You must compute with sensor dimensions in mm.

Howtocalculate focal lengthPhysics

Howtocalculate focal lengthof convex lens

The triangles (large and small) are similar, that is angles are the same. So Angle of view will be the same as top angle (at the lens) of the smaller triangle. From that, since you know what sensor size and angle of view is, you can calculate focal length in pixels, as @remco calculated for you.

In fact, units of the sensor size should be exactly the same as units of the focal length to make sense of F=A/tan(a). What you can get from that is, if you have bigger pixels (in cm), you will need larger focal length (in cm) for same field of view and number of pixels.

Larger sizes of up to 24" x 39" are also available. To order a custom-sized film polarizer, please contact Tech Support. We also offer film polarizers with AR-coated windows epoxied on each side in Ø1/2", Ø1", and Ø2" sizes.

Howtocalculate focal lengthof parabola

The polarizing materials are designed and optimized for use within their operating range, denoted in the graphs below by the blue highlighted regions. Outside of this range, the performance of these polarizers' is not guaranteed. Care should be taken when cleaning and mounting these polarizers, as significant stress may cause performance variation. We recommend using compressed air to remove dust and debris.

It is what Hermann said, focal length is NOT measured in pixels. I strongly doubt the engineering journal said focal length was pixels.

The article specifies that the horizontal FOV is 47°, so we have to use A = 640/2 = 320, a = 47°/2 = 23.5°, which give F = 736 pixels.

Thorlabs offers a diverse range of polarizers, including wire grid, film, calcite, alpha-BBO, rutile, and beamsplitting polarizers. Collectively, our line of wire grid polarizers offers coverage from the visible range to the beginning of the Far-IR range. Our nanoparticle linear film polarizers provide extinction ratios as high as 100 000:1. Alternatively, our other film polarizers offer an affordable solution for polarizing light from the visible to the Near-IR. Next, our beamsplitting polarizers allow for use of the reflected beam, as well as the more completely polarized transmitted beam. Finally, our alpha-BBO (UV), calcite (visible to Near-IR), rutile (Near-IR to Mid-IR), and yttrium orthovanadate (YVO4) (Near-IR to Mid-IR) polarizers each offer an exceptional extinction ratio of 100 000:1 within their respective wavelength ranges.