APPLICATION OF LASERS IN

CUTTING,WELDING,DRILLING AND EYE SURGRIES

Presented by:

Ajay Singh

Physics Department Indian Institute of Technology Delhi

Heating

Cooling

Imaging

Communicati

on

Laser processing of materials (Sadhana Vol. 28, Parts 3 & 4, June/August 2003, pp. 495–562)

Laser–matter interaction in material processing

laser–matter interaction within the near-surface region achieves extreme heating

and cooling rates (103–1010 K/s), while the total deposited energy (typically, 0·1–

10 J/cm2) is insufficient to affect, in a significant way, the temperature of the bulk

material. This allows the near-surface region to be processed under extreme

conditions with little effect on the bulk properties.

Laser Heating:Coupling of laser radiation to electrons within the metal. Energy high

but per photon energy < work function of the material.

Energy absorption

Spatial distribution of

deposited energy

Heating due to laser

irradiation

LASER Cutting

Either using a transmissive (glass) or reflecting (metal mirror) optics.

The transmissive optics is made of ZnSe, GaAs or CdTe lenses for CO2

lasers or quartz lenses for YAG or excimer lasers. (LASER damage threshold

)….

The reflective optics consists of parabolic off-axis mirrors. The main

constituents for control and monitoring are the lasers with shutter control,

beam guidance train, focusing optics and a computer controlled translation

stage to move the work-piece.

Wavelengths 1.064µm (Nd-YAG), 10.6µm or 9.4µm(CO2 )

High power CO2 lasers or Nd:YAG lasers

Both pulse and continuous wave modes

Mechanical punching is fast but is limited to holes further than 3 mm diameter.

Electro chemical machining is too slow at 180 s/hole but does give a neat

hole.

Electro discharge machining is expensive and slow at 58 s/hole. Electron

beam

drilling is fast at 0·125 s/hole but needs a vacuum chamber and is more

expen

sive than aYAG laser processing. In comparison, aYAG laser takes 4 s/hole

to

outsmart all other methods [1].

LASER Drilling

Laser joining is applicable to inorganic/organic and similar/dissimilar materials

with an extremely high precision, versatility and productivity that can only be

matched by electron beam welding. Moreover, laser welding can be done in air,

unlike the vacuum processing needed in electron beam welding. In comparison

to conventional or arc welding, laser welding scores several advantages like

narrow welds with controlled bead size, faster welding with a higher productivity,

less distortion, narrow heat affected zone, amenability to welding Al/Mg alloys

and dissimilar materials, and minimum contamination.

pulsed or continuous wave Nd:YAG or CO2 laser (very seldom ruby laser, too)

are the commonly used lasers for joining. The main process variables in laser

welding are laser power, beam diameter, beam configuration, travel speed of the

work-piece, substrate condition (roughness, temperature), filler type/feed rate,

alloy composition and thermophysical properties of the work piece.

LASER Welding

Figure : Schematic of laser welding without a filler rod (front

view) . The argon shroud removes heat and prevents

undue oxidation. The relative position of the laser focus

determines the quality and configuration of the weld.[2]

Source: http://www.uslasercorp.com/envoy/welding.html

Refractive Eye Surgery

Refractive eye surgery is eye surgery used to improve the refractive

state of the eye and decrease or eliminate dependency on glasses or

contact lenses. This can include various methods of surgical remodelling

of the cornea or cataract surgery. The most common methods today use

excimer lasers to reshape the curvature of the cornea. Successful

refractive eye surgery can reduce or cure common vision disorders such

as myopia, hyperopia and astigmatism, as well as degenerative

disorders like keratoconus.

In Laser surgery surgery, the curvature of the cornea is altered by

removing a specific amount of corneal tissue with ultraviolet photo-

ablation from the excimer laser.

http://ildenaro.it/blog/2014/02/27/riparazione-della-cornea-al-monaldi-il-laser-supervoloce/

1950’s – Columbian Jose Barraquer developed Microkeratome

& keratomileusis techniques and discovered root causes for eye

trauma

1970’s – Russian Svyatoslav Fyodorov developed Radial

Keratotomy (and posterior chamber implantable contact lenses

in 1980)

1970’s – Development of Excimer Laser (origin of LASEK laser)

1982 – 3 Members of the IBM research team discovered the

laser could be used to remove biological tissue without heat

damage to surrounding tissue

1987 – Dr. Steven Trokel performed the 1st laser surgery on a

patients eye

1996 – Lasik Eye Surgery became officially approved by the

U.S. government

BRIEF HISTORY

CLASSIFICATION

REFRACTIVE SURGERIES

CORNEA BASED LENTICULAR BASED COMBINED(BIOPTICS)

-R.K.

-PRK

-LASIK/Intra

LASIK

-EPILASIK

-LASEK

-Conductive

Keratoplasty

-Corneal Inlays

and rings

-Clear Lens

extraction for

myopia

-Phakic IOL

- Prelex Clear

Lens Extraction

with use of

Multifocal IOL’s

Combination

of the two

A) Radial keratotomy (RK)

B) Excimer laser photorefractive keratectomy ( PRK )

C) Laser assisted in situ keratomiliuses (LASIK)

D) Laser assisted subepithelial keratomiliuses ( LASEK )

E) Laser thermokeratoplasty (LTK )

D) Intracorneal ring segments (ICRS)

G) Phakic intraocular lenses (IOLs )

Various types of laser surgery are used to treat refractive error:

LASIK : knife is used to cut a flap in the cornea, and a laser is used

to reshape the layers underneath, to treat refractive error.

IntraLASIK: a variant in which the flap is also cut with a laser

Photorefractive keratectomy (PRK, LASEK), in which the cornea is

reshaped without first cutting a flap

Laser thermal keratoplasty: in which a ring of concentric burns is

made in the cornea, which cause its surface to steepen, allowing

better near vision

Various types of laser surgery are used to treat refractive error:

LASIK : knife is used to cut a flap in the cornea, and a laser is used

to reshape the layers underneath, to treat refractive error.

IntraLASIK: a variant in which the flap is also cut with a laser

Photorefractive keratectomy (PRK, LASEK), in which the cornea is

reshaped without first cutting a flap

Laser thermal keratoplasty: in which a ring of concentric burns is

made in the cornea, which cause its surface to steepen, allowing

better near vision

Lasers are also used to treat non-refractive conditions, such as:

Phototherapeutic keratectomy (PTK), in which opacities and surface

irregularities are removed from the cornea

Laser coagulation, in which a laser is used to cauterize blood

vessels in the eye, to treat various conditions

Lasers can be used to repair tears in the retina.

Types of lasers used-

Excimer-Excited dimer of two atoms

-An inert gas(Argon)

-Halide(Fluoride)

which releases ultraviolet energy at193nm for corneal ablation

Non-Excimer solid state lasers-

210nm Q switched diode pumped laser

213 nm Q switched diode pumped laser(Pulsar)

Types of lasers used-

Excimer-Excited dimer of two atoms

-An inert gas(Argon)

-Halide(Fluoride)

which releases ultraviolet energy at193nm for corneal ablation

Non-Excimer solid state lasers-

210nm Q switched diode pumped laser

213 nm Q switched diode pumped laser(Pulsar)

Advantage of Non-Excimer solid state lasers-

No toxic excimer gases

Wavelength closer to absorption peak of corneal collagen—less

thermal and collateral damage

Better pulse to pulse stability

Not absorbed by air, water, tear fluid-so less sensitive to humidity or

room temperature

No purging with inert gases required.

PROCEDURE

Step 1 : Creating corneal flap

Step 2 : Folds the flap back and perform

laser procedure which corrects

vision .

EXAMPLES OF CORRECTION

The surgery is typically done within 30 minutes or less-quick & painless

Most people achieve 20/20 vision (or even better) afterwards (90% reachdesired vision after LASIK)

May still need glasses/contact lenses, but prescription is much lowerthan before

A small percentage of people have an enhancement (minor touch up)surgery later for further improved vision

Requires no bandages or stitches

Research conducted by the Magill Research Center for VisionCorrection, Medical University of South Carolina, showed that the overallpatient satisfaction rate after primary LASIK surgery was 95.4%. Theyfurther differentiated between myopic LASIK (95.3%) and hyperopicLASIK (96.3%). They concluded that the vast majority (95.4%) of patientswere satisfied with their outcome after LASIK surgery.

ADVANTAGES OVER NON-LASER SURGERIES

Some patients lose vision.

Some patients develop debilitating visual symptoms.

You may still need eyeglasses after surgery.

Some patients may develop severe dry eye syndrome.

For some farsighted patients, results may diminish with age.

Long-term data is not available.

Potentials Risks

Also The LASER eye surgery is not for you if you are

You required a change in your contact lens or glasses prescription in the

past year. This is called refractive instability.

You have a disease or are on medications that may affect wound healing.

You actively participate in contact sports. You participate in boxing,

wrestling, martial arts or other activities in which blows to the face and

eyes are a normal occurrence.

But Still the success rate > 95%, further

improvements going on

Works Cited

http://en.wikipedia.org/wiki/Refractive_surgery

http://www.worldoflasers.com/laserapplindustrial.htm

http://en.wikipedia.org/wiki/LASIK

http://www.firstlight-laser.com/about.html

http://en.wikipedia.org/wiki/Laser_surgery#Eye_surgery

http://ildenaro.it/blog/2014/02/27/riparazione-della-cornea-al-monaldi-il-laser-supervoloce/

http://www.powershow.com/view/14b8bb-ZjY4N/Lasers_in Manufacturing_

http://www.uslasercorp.com/envoy/welding.html

http://laneconference.org/downloads/IndustrialContributions/LANE2014_Naeem_Flexible

_laser_system.pdf

Other references:

[1]. SteenW M (ed.) 1991 Laser material processing (NewYork: Springer Verlag)

[2]. Laser processing of Materials “J DUTTA MAJUMDAR and I MANNA ”(S¯adhan¯a

Vol. 28, Parts 3 & 4, June/August 2003, pp. 495–562)

[3]. T. Juhasz, G. Djotyan,F. H. Loesel*R. M. Kurtz*C. Horvath* J. F. Bille***, and G.

Mourou* “Applications of Femtosecond Lasers in Corneal Surgery” (Laser Physics, Vol.

10, No. 2, 2000, pp. 495–500.)

[4] Boulnois, J.-L., 1986, Lasers in Medical Science, 1, 47.

[5] Niemz, M.H., 1996, Laser Tissue Interactions: Fundamentals and Applications

(Heidelberg: Springer).

[6] Rykalin N N, Uglov A, Kokora A 1978 Laser machining and welding (Moscow: Mir)

Thanks For

Your Kind Attention