Calculation formula of spatial resolution

What is the resolution of Abbe formula?

Theoretical formula: resolution =0.6 1* light wavelength/n.a. Therefore, to improve the resolution, it is necessary to use illumination light with shorter wavelength and increase the numerical aperture of the objective lens. In 1970s, Ernst Abbe, a German physicist, discovered that visible light could be diffracted due to its wave characteristics, so the light beam could not be focused indefinitely.

Accordingly, the resolution limit is about λ? 2n, where λ is the wavelength of light wave and n is the refractive index of sample medium. 1994, StefanHell of Germany proposed the stimulated emission (STED) technology, which was used to break the Abbe limit and realize ultra-high resolution imaging.

The Abbe diffraction formula of lateral (i.e. XY) resolution is: d=λ/2NA, where λ is the wavelength of light used for specimen imaging. If green light with 5 14nm and oil-immersed objective lens with NA of 45 are used, the (theoretical) limit of resolution will reach 177nm.

Calculation formula of ct spatial resolution

The calculation formula of ct spatial resolution: ppi= root sign (x+y)/Z. The resolution of CT can be divided into spatial resolution and contrastresolution, which are two indexes to judge CT performance and explain image quality.

The conversion relationship is: 5÷Lp/cm= minimum diameter of identifiable object (mm).

One of the indexes of computer tomography performance and image quality, if the density resolution of computer tomography is 0.5%, it means that two substances can be distinguished when the density difference is equal to or greater than 0.5%, but when the density difference is less than 0.5%, they cannot be distinguished due to noise interference.

Carat (symbol: CT) 1 carat = 0.2g (200mg) The full name of CT in medicine: computedtomographyCT is a fully functional disease detection instrument, which is the abbreviation of computerized X-ray tomography technology.

How many pixels is the 700 line?

In the picture of 16: 9, 700 lines are divided into 720 HD specifications of 1270*720 =9 1w pixels according to the video division rules. The full HD specification is 1920* 1080, which means 1000 lines, which is about 200w pixels. The standard definition PAL to be eliminated is 720*576(NTSC is 720*480) with 500 lines, which is about 40w pixels.

16: 9 has 700 lines, so 700* 16/9= 1244, and the actual resolution is 700* 1244, that is, 871165438. 700 lines of standard definition PAL is 720*576(NTSC is 720*480), which is about 40w pixels.

Pixel conversion method of line monitoring camera: when the screen ratio of the connected camera is 4: 3, it is 700*4/3=933, and the actual resolution is 700*933, and the 420 lines are about 653,333 pixels, that is, 650,000 pixels.

The concept of spatial resolution

1, the spatial resolution is defined as the line pairs that can identify the bright and dark stripes on the chopping block within a unit distance, and the unit is the line pairs per millimeter (lp/mm), that is, the minimum ground distance that can be identified or the size of the minimum target object when converted into an actual object according to the scale.

2. Under the unit test distance, the minimum target (area) that can be detected by each pixel of the infrared thermal imager is a comprehensive performance parameter mainly determined by the pixel and the selected lens angle in mRad, and it is a technical index of the thermal imager's ability to deal with spatial details.

3. Spatial resolution refers to the size of the ground range expressed in pixels, that is, the instantaneous field of view of the scanner, or the smallest unit that ground objects can distinguish. Chinese name: spatialresolution mbth: spatial resolution understanding: spatial resolution refers to the minimum distance between two adjacent features that can be recognized in remote sensing images.

4. Spatial resolution is also called high contrast resolution. Refers to the smallest detail that can be displayed in the image when the density resolution is greater than 10%, or refers to the ability to identify the size of the structure.

How to evaluate the performance of cloud data warehouse?

1. Performance issues include: the geographical location of applications and data relative to end users, the I/O access speed in the cloud, inside and outside the cloud, and between the computer layer and the data storage layer.

2. When testing the performance of the mobile cloud hard disk, it is necessary to create the cloud hard disk to be tested and mount it on the cloud host. Due to the performance error of different testing tools, it is suggested to use FIO as the testing tool for cloud hard disk products.

3. Under Windows, we usually use IOMeter to test the performance of the disk. IOMeter is not only powerful, but also professional, and it is the first choice for testing disk performance. IOMeter is a graphical interface (MFC framework has a strong flavor), which is very convenient to operate. I will use IOMeter to test 1TB cloud hard disk on our UOS.