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Laser emission’s harm to human eye

Updated:2011/3/17 6:37:37  Source:hanzlaser  Edit:hanzlaser  Views:

 

 

 

Laser emission’s harm to human eye  

   Due to the feature of laser, energy is highly concentrated both in space & time. By means of dioptric medium focusing of eye, image is shaped on retina, which cause energy density on retina raised 104105 than incoming energy density from cornea; laser with good monochromaticity, so there is few chromatic aberration on eye ground. Because of the above features, even knockdown laser energy irradiating would harm cornea or retina.  

   Laser wavelengths & Injury parts of eye  

Wavelength partition  

wavelength coverage  

main injury parts  

YAG  

180—400    

cornea/crystalline lens  

Visible laser  

400—700  

retina/choroid  

Near-infrared laser  

700—1400  

retina/choroid/ crystalline lens  

Middle & far infrared laser  

1400—106       

    cornea  

   

        

Eye ground’s effective absorptivity to several laser light  

Laser  

Wavelength  

(nm)  

Absorptivity  

(%)  

Medium transmissivity  

(%)  

Effective absorptivity  

(%)  

Nd laser  

1064  

12  

42  

5.04  

Ruby  

694.4  

56  

96  

53.7  

Ar+  

488-514  

70  

80  

56  

Frequency doubling  

Nd: YAG  

532  

74  

88  

65  

   Including retinochrome epithelium and choroid’s absorption  

   Cardinal symptom of laser injury accidents

  When accident happening, most of injured persons feel sudden glint at the present, then appear a colorful and different sizes light spot or shadow, someone’s eyes have impactive feeling, meanwhile, vision descend to varying degrees, serious ones couldn’t distinguish objects at the present in short time, some ones feel dizzy and lucifugous in several hours.  

Reasons and lessons  

{C}1.      {C}No safeguard procedures for eyes at work  

{C}2.      {C}Lack safe work environment  

{C}3.      {C}Torpid thoughts  

{C}4.      {C}Laser triggered unmeant  

{C}5.      {C}In clinical ophthalmology laser Treatment, doesn’t strict control treatment energy.  

   

Workers who work in laser operating environment for long time, theirs eyes would be long-term influenced by laser light. When operating and using optical maser, even though no direct laser shining and no injury accident, but radial from laser would engender trace reflection through other objects or wall; people who work in such environment for long time, morbidity of cataract is high.  Min optical density of human eye safeguard requirements to several typical laser sources   

Laser  

emission means  

output power/energy  

irradiation limit  

optical density  

Frequency doubling  

Nd: YAG  

giant pulse  

100 mJ  

5.0×107J/cm2    

6.0  

Cu vapour  

continuous  

5 W  

1.8×10-3W/cm2  

4.1  

Ar+     

continuous  

5 W    

1.8×10-3W/cm2    

4.1  

continuous  

50 mW  

1.8×10-3W/cm2    

2.1  

   

Nd: YAG    

continuous  

80 W    

9.6×10-3W/cm2  

4.6  

long pulse  

400 mJ  

5.0×10-6J/cm2    

5.6  

giant pulse  

100 mJ  

5.0×10-6J/cm2  

5.0  

CO2    

continuous  

80 W  

5.6×10-1W/cm2  

2.9  

   

 

 

 

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