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To measure the FOV of UV, visible and infrared cameras, optical tests are commonly used. During the test, light is focused from a black body (an object that absorbs all light that falls on it) onto a test target at the focal place. By using a set of mirrors, a virtual image can be created that is at an infinitely far distance.

depth offield中文

This means that the distance of the focal length is determined by how strongly the light is converged by the lens in order to focus the subject being imaged. This, in turn, influences the angle from the horizonal of light that can be captured by the lens. This is known as the angular field of view (AFOV) and is required to determine the overall FOV. The AFOV is the angle between any light captured at the horizonal, and any light captured at the edge (as shown in Figure 2). If you have a fixed sensor size, altering the focal length will alter the AFOV and therefore the overall FOV. A shorter focal length provides a larger AFOV view, and therefore a larger FOV. The same is true but vice versa for longer focal lengths, as indicated in Figure 2.

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An objective lens for which spherical and coma aberrations have been corrected may not be able to converge object points off the axis to a point, separating those points into a segment image in a concentric direction and that in a radial direction. This aberration is known as "astigmatic aberration". An objective with any astigmatic aberration will change the blur orientation of a point image to longitudinal or lateral with respect to before or after the focal point.

Sensor size is determined by both the size of the pixels and number of pixels on the sensor. This can be optimized for each application, with larger sensors optimal for sensitivity limited applications, and smaller sensors optimal for resolution limited applications.

Field of view vsangleof view

There are many subcategories of UV light, each which need different sensor requirements. These include both physical and chemical sensor changes.

fov是什么

Microscope optical systems have a slight distortion aberration. This distortion aberration may cause a measurement error in geometric measurement.

Acton optics and coatings provide ultra-precision optical components and coatings with an emphasis on the UV/VUV spectral regions.

Field of view (FOV) is the maximum area of a sample that a camera can image. It is related to two things, the focal length of the lens and the sensor size. Figure 1 shows a comparison between the field of view and the size of the sensor. Assuming that the focal length of the lens is the same, the larger the sensor the larger the field of view.

There are two processes which can be used to enhance UV sensitivity for wavelengths >200 nm: UV photon conversion, and anti-reflection coatings.

Where D is the full display image dimensions (either horizontal or vertical), and d is the target dimensions (either horizontal or vertical).

The glass used for an optical system has the property of being different in refractive index according to each wavelength of light. This causes a difference in focal length according to each wavelength, resulting in a deviation of image-forming position. This phenomenon is called "chromatic aberration". Particularly, an axial deviation of focal length on the optical axis is called "axial chromatic aberration" (also called lateral chromatic aberration) and a deviation on the image plane is called "chromatic aberration of magnification", respectively. Olympus takes an excellent corrective action against chromatic aberration using various types of glass. Chromatic aberration has been eliminated particularly from the apochromatic (MPlanApro) objective in a wide range between bluish-violet (g ray: wavelength 435nm) and red (C ray: wavelength 656nm).

Deepdepth of field

A phenomenon in which the shape on an object plane will not become similar to that on an image field is known as "distortion aberration". An objective lens with any distortion aberration deforms a square image to a barrel shape or pincushion shape.

Field of view defines the maximum area of a sample that a camera can image, determined by the focal length of the lens and the sensor size.

The sensor size is determined by both the number of pixels on the sensor, and the size of the pixels. Different sized pixels are used for different applications, with larger pixels used for higher sensitivity, and smaller pixels used for higher spatial resolution (find out more on Pixel Size and Camera Resolution).

See how others are using our high-performance cameras, spectrographs and optics-based solutions to advance their research and application.

field ofview中文

The focal length of a lens converges light so that the image of an object is focused onto the sensor. This determines the angular field of view, a parameter of the overall field of view. This is defined as the angle between any light captured at the horizontal and any light captured at the edge of the of the object. All of these parameters play a role in determining the FOV of a camera and can be measured using either trigonometry and the angular field of view, or via an optical test, in which a black body is utilized to create a virtual image

The gain relates the number of photoelectrons released to the gray levels displayed, and can be used to enhance contrast for low-light imaging.

Depth of fieldcalculator

Shallowdepth of field

The focal length of the lens describes the distance between the lens and the focused image on the sensor. As light passes through the lens it will either converge (positive focal length) or diverge (negative focal length), however within cameras the focal length is predominately positive. Shorter focal lengths converge the light more strongly (i.e. at a sharper angle) to focus the subject being imaged. Longer focal lengths, in comparison, converge the light less strongly (i.e. at a shallower angle) in order to focus the image.

When light beams emitted from an object point on the axis are launched into a lens, the beams with a higher numerical aperture (N.A.) are refracted more greatly, crossing the optical axis away from the ideal image-forming position. An aberration due to variations of image-forming positions depending on the difference in numerical aperture (N.A.) of light beams on the axis is known as "spherical aberration". (A spherical aberration is proportional to the cube of a numerical aperture (N.A.).)

This allows the FOV dimensions (i.e. vertical and horizontal distances) to be measured without knowing lens focal length or sensor size. The image created, including the target, is then displayed on a monitor, with the target image being a subset of the full image display. This allows the FOV to be approximated as:

An objective lens is known to increase the resolving power as the numerical aperture (N.A.) increases, but this tends to deteriorate the spherical aberration. Olympus's objectives posses an excellent optical performance irrespective of high numerical aperture (N.A.) thanks to sophisticated design and production technologies.

Above aberrations (1) to (3) signify "spread of image points" against requirement (i) for ideal image forming, aberration (4) signifies "curvature of field" against requirement (ii), and (5) signifies "geometrical distortion" against (iii). Also, aberrations (6) and (7) signify "chromatic blur" on an image caused depending on the characteristic of glass material used for an optical system. Meanwhile, to include the effect of diffraction of light, "spread of image points" may also be referred to as "wavefront aberration", also taking the phase into account with light assumed as "wave".

The image field of an object on a plane perpendicular to the optical axis is not always a flat surface perpendicular to the optical axis, but generally a curved surface. This phenomenon is called "field curvature aberration". If an objective lens has a field curvature aberration, an image will differ in position toward the periphery of a field of view. Therefore, if the center of the image is brought into focus, the periphery of the image becomes out of focus. To obtain a clear image up to the periphery, it is required to sufficiently correct this aberration.

Figure 3 shows a simplified version of how these assumptions allow for AFOV calculation. By using trigonometry, the AFOV can be expressed as:

Even if a spherical aberration is corrected sufficiently small, the light beams emitted from the object points off the axis may not converge on one point in the image field, leaving an asymmetric blur with a trail like a comet. This aberration is known as "coma aberration".