Kiến thức
CCTV system
Section 4: CCTV system: What is the image sensor?
Section 3: Principle of camera
Section 2: CCTV system: Principle of Eyes
Section 1: What is CCTV system?
BMS system
Section 3: BMS system: Software of system
Section 2: BMS system: Point list
Section 1: What is BMS system?
Access control system
PA system
Fire alarm system
Section 1: What is fire alarm system?
Smart home solution
Section 2: CCTV system: Principle of Eyes
Meper, 05-09-2015
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They say humans are marvels of nature, the human eye is the masterpiece of ... masterpieces. Indeed, the eyes not only a visual but also may be other senses, so people say, "The eyes are the windows to the soul". From past to present, people still ply design and complete CCTV system to fully simulate the operation of the eyes but only achieved very limited.
CCTV Systems was invented for the purpose of remembering the image of things on camera and then remember, reconstruct on monitors.
1. Structure of the eyes
The eyes is made up of the eyeball, muscles to adjust the eyeball (called "extraocular muscles"), together with the eye socket and facial nerve, eyelids, eyelashes, lacrimal and synaptic membranes. Extraocular muscles have the task of adjusting the viewing angle of the eye (such as a girl who is ogling).
Eyes have very important functions:
- As part acquisitions and "coded" information to the brain.
- As the optical system, collecting grab image.
- As an authority, "service" for human life.
- Cornea: The light in her eyes partially refracted in the cornea. The cornea, the room rate, pupil, lens (lens) and functional glass service to penetrate and reflect light, so they are called trans-light environments.
- Glass can: role of a lens to focus light on the retina. It was suspended by the round ligament with ciliary body. The vitreous mi adjust to change focus so that we can look away or close objects. Between the cornea and crystalline lens is fluid between the vitreous and the retina is the vitreous. Both fluid keeps the eye does not collapse.
- Vestibule and backroom: A recess between the cornea and the iris is called the room, against the hollow seal around behind the iris and the lens horizontal constriction (eye lens) is called the post room. Both rooms were filled with fluid.
- The iris (the pupil): the holes between the iris diaphragm. The largest portion of the hollow behind the lens is filled with a clear fluid called the vitreous (corpus vitreum). Glass table that can be called the friend (mi) (zonula ciliaris Zinni) horizontal membrane stretched between the vitreous and dear friend (corpus ciliare).
- The muscles of the eyes: also involved in a number of eye function. The iris adjusts the pupil diameter. Ciliary body may alter the curvature of the lens. The external control eye eyes turned toward the visual target.
- The retina and optic nerve are part sequential receipt and transmission of light impulses. The middle part of the retina called the macula (macula lutea) have the most sensitive functions.
The retina is a "light-sensitive area" contains millions of cells called cones (cones) and rods (rods). These cells are part of the nervous system. The cone cells sensitive to light medium and slightly harsh, they brought to the color, the rod cells sensitive to light lesser extent, we do not recognize color. Rod cells are used at night, in the dark so people do not recognize color.
Cone cells in the human eye is about 10 million rod cells and the amount of 100 million. Cone cells concentrated in the area around the optical axis of the pupil. This region is known as pit gold color vision (foeva). This pit area visual focus brain information processing. Despite the small size, but focused around 50,000 cones. Focal length human eye (distance between the lens and the retina when looking at distant objects amorphous) is of 17mm. Focal length to a precise image at an angle of about 30 °. In this corner concentrate supply cones. So a 30 ° angle is considered the standard.
These cones have focused increasingly on the optical axis center, primarily within the angle of 10 °. Each cone is connected to the brain via the optic nerve separately, where the signal is sent to the brain. The viewer's eye is much broader angle for retinal surface coated with a supply of about 90 ° and also the yellow cone cells, but these cells are connected to nerves in groups. Photos received no clear than photos from the nerve cells separate, so this area is called the peripheral vision.
"The image processor" brains concentrate at 30 °, but the most visible in the eyes of about 10 °. The process is enhanced by movement of the eyeballs in all directions, this wallet equivalent parts rotate / flip (pan / tilt) in CCTV.
2. The light and the human eye:
Since light is often used to refer to electromagnetic radiation of a wavelength that we are in the human eye spectral region visible (wavelength radiation in the range of 380 nm to 740 nm). Light is particle motion waves which people often called photons. Type of light from the sun shining down called sunshine (also known as the white light, they include many light monochrome continuous variation from sheet to sheet purple red); Moon light shining down from the earth is called the moon, actually reflected light to the earth when the sun shines on the moon. Light generated by the bulb is usually called light; light emitted by the animals is often called a biological light.
"Cold light" means light with a wavelength spectrum focuses almost purple. But the concept of "Hot Light" is to talk about light having a wavelength located near the red spectral region.
White light with a spectrum from red to violet, and light having a wavelength spectrum concentrated in a very narrow area called "monochromatic light".
3. The principle of operation of the eye:
When looking at an object, the light from the object passes through the cornea transparent. The light will be refracted part (not going into the vitreous). The rest are moderated passing through the pupil and lens guide. The lens is made up of the focusing lens with a focal length can be changed. Image objects upside will converge on the retina. When distant objects close to the lens or to contract and relax to adjust the focal length so that the picture always falls on the retina. The electric signals by the retina cells created will follow the line to the optic nerve to the brain, where the image is reversed to the correct dimensions.
