Test 15  (Laser)
1. The following are properties of laser:
a. it is entirely monochromatic

b. all the photons are in phase

c. all the photons have the same wavelengths

d. the waves of light are parallel

e. the distance between the mirrors within a laser tube is a 
    multiple of the wavelength of the light emitted.

2. The following are true about the modes of laser output:
a. both Q-switched and mode-locked mode increases the 
    laser energy by compressing the energy in time.

b. mode-locked produces more power than either 
    continuous or Q-switched mode

c. the duration of a pulse of laser produced by 
    mode-locked mode is shorter than that of Q-switched 

d. in Q-switched mode, a shutter is placed inside the laser 
    tube to limit energy loss.

e. laser from continuous mode has a constant power and 
    is measured in watts.

3. Regarding the Nd-YAG laser:
a. it emits infrared radiation

b. it is invisible

c. doubling its frequency makes it suitable for retinal 

d. it is usually mode locked when used to treat the eye

e. it is used to create iridotomy

4. Regarding argon laser:

a. it produces a wavelength of between 488-514nm.

b. argon blue laser is the preferred choice during 

c. the xanthophylls in the macular absorbs argon green 
    better than argon blue laser.

d. a white burn is the end point during panretinal 

e. a higher energy is required for lighter than pigmented 

5. The following laser investigations can be used to monitor the 
     progression of glaucoma:

a. confocal microscopy

b. laser interferometry

c. confocal scanning laser tomography

d. scanning laser polarimetry

e. laser Doppler flowmetry

6. True statements about laser safety include:

a. laser with output energy of 5mW or more is damaging 
    to the eye.

b. lasers of class 3a and above are detrimental to human

c. argon laser used for retinal photocoagulation is class 3b

d. the eye is more sensitive to laser damage than the skin

e. safety goggles are not necessary for visitors during 
    YAG capsulotomy.

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