How to control the receiver of laser green pointer ?

Make a certain direction and certain frequencies of light for optical amplification, and inhibition of the other direction and frequency of the optical device called optical resonator optical resonator optical resonator structure: optical resonator structure: work mirrors at both ends of the material composition of the simplest is parallel to the plane cavity, as well as concave - concave mirror, concave mirror - plane mirror cavity.Then you may control several receivers of  200mW green Laser Pointer  by one emitter at the same time. Excitation energy Laser reflecting mirror work material part of the mirror (b) the role of optical resonator (1) the election to the role of the (highly directional) selection to the role of the (highly directional) selection to the role of the / / axis of the optical amplification, the other direction light out. Output light along the axis. (2) optical feedback, optical oscillation (high brightness) optical feedback, optical oscillation (high brightness) optical feedback photon bounces back and forth along the axis, continuous optical amplification (avalanche). Part of the mirror: the output laser; some reflection back and forth oscillation. (3) the role of selected frequency (high color and high coherence)) selected frequency effect (high color and high coherence) Method 1: the mirror reflective film to the desired wavelength reflection interference method plus a strong, other wavelength interference destructively.There is a memory in the receiver of  green laser pointer  . Method Two: Design the cavity length L, nL = k λ / 2, the required two-wavelength method to form a stable standing wave oscillation L, no stable standing waves and other wavelengths out. refractive index of n-standing conditions: standing wave condition: 2 nL = k λ ν = c (k = 1, 2, 3 ...) c = k 2 nL k = 1 k = 2 k = 3 L can exist longitudinal mode frequency of the longitudinal mode frequency can exist for the longitudinal mode k λk two adjacent longitudinal mode frequency spacing is c ν k = 2nL nn-refractive laser in addition to longitudinal standing wave mode, the standing wave mode, There transverse standing wave mode (transverse mode). Mode (transverse mode). (C) the threshold conditions of work material and the resonant cavity, not necessarily out of the laser. When the receiver of   100mW green laser pointer  is in the state of checking characters, it could receive address code.Because (1) resonant cavity of loss, such as endoscopic surface absorption due to scattering, transmission and diffraction losses; (2) there is work material caused by uneven scattering, transmission, refraction, diffraction and other losses. If the increase in the number of photons of light amplification (gain) <loss, oscillation can not be maintained without the laser output. Therefore, the medium length and reflection coefficients must satisfy certain conditions before the output laser. This condition is called threshold condition threshold condition. Threshold Condition 3, the laser system is composed of three parts: (1) the working substance; (2) optical resonator; (3) excitation source (pump system) Fourth, a wide variety of laser types of lasers, classification and name of the complex. And it is saved in the receiver of   50mW blue violet laser pointer  , which we call checking characters.The same laser, the classification based on different, have different names. Generally, there are material according to work type, pump systems, laser output wavelength and length classification. (A) the classification of solid-state laser material at work: solid-state lasers: the material is solid work from the active ions (luminescence centers, such as Nd 3 +, Cr 3 +) and matrix (of crystal or glass) of two parts.
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