Wavelength of 1.4-2.0 um is less harmful to the human eye, so a laser with this wavelength range is called the human eye-safe laser. This wavelength range is located in the atmospheric transmission window, the absorption and scattering of the laser is only 1/50 of the 1.06um laser, which is of great significance for long distance action, especially for military applications.
Theotry
The main components of device are:
Er glass gain medium
The bismuth glass Yb:Er:glass is a three-level system, and the stimulated emission of 4I13/2→4I15/2 of Er3+ produces a 1535nm human eye safety laser.
Co: Spinel is an efficient passive q switching material in lasers emitting from 1200 to 1600 nm. This crystal has a high absorption cross section(3.5×10 – 19 cm2) which can make Q-switch of Er,Yb: glass laser work without intracavity focusing both with flash lamp and diode-laser pumping.
Co Spinel Q-Switch
LD pump——The center wavelength of the LD pump is 940-980 nm, which is exactly at the absorption peak of the Er glass.
Feature
- Beam quality near diffraction limit
- Small volume
- Low power consumption,
- no temperature control
- Open and be used
- High reliability
- Good stability
- Wide temperature range
Application
Ranging
Laser diode (LD)-pumped Er glass passively Q-switched all-solid-state lasers produce lasers with a center wavelength of around 1.535μm, greatly reducing eye damage, beam quality, high conversion efficiency, and simple and compact structure. It is easy to carry and can be used in relatively harsh outdoor environments.
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| Eye-safe laser range finder |
The ranging module composed of eye-safe laser can be applied to the following fields
- Military project
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| Thermal imaging telescope | Night vision scope |
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| Weapon Sight | Laser active anti-sniper detector |
- Intelligent Transportation System
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Parking spot detection The ranging module is used to detect whether the parking spot is occupied and how long it is occupied. | Automatic toll collection station The ranging module detects the distance of the vehicle traveling toward the toll booth. When the distance is shortened to a certain distance, the recording camera open ，begin to record the incoming vehicle information, and when the vehicle travels past, the recording camera turn off. |
- Robot field
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| Navigation and obstacle avoidance |
Range finder combine with GPS technologies form a ranging positioning system,used in following fields
- UAV
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- Vehicle-borne thermal imager
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