Download - Optical Tweezers
Optical TweezersTeam:
Maryam Badakhshi,Shannon O’Keefe,
Laura Poloni,Hasmita Singh
Overview1) Introduction2) Background & Applications3) Apparatus4) Laser Safety
1. Introduction
Experiment Context
2. Background & Applications
Manipulation of Nanowires
(Tong et. al., Nano Letters, 2010)
• Alignment and rotation of a silver nanowire
(Nam et. al., IJPEM, 2009)
• Four spheres trapped and rotated by linearly scanning with laser light
(Gross et. al., Methods in Enzymology, 2010)
Isolation and Visualization of DNA
Trapping of two beads
“Catching” a Single DNA Molecule
Force-Extension analysis of the trapped DNA
Staining with Fluorescent Dye
Protein-coated DNA region
Fluctuations in DNA molecule
(Gross et. al., Methods in Enzymology, 2010)
3. Apparatus
Main Components Very
Dangerous!Safe!
4. Laser Safety
Optical Trap Laser Characteristics980 nm Infrared range330mW maximum powerCollimated beamClass 3B laser
Laser Classification
Class 3B Laser
Safety Interlock
s
Class 1 working environment
• Hazardous under direct and specular reflection, but not diffuse reflection• Direct exposure to beam is an eye hazard• Maximum power 500mW
• Considered incapable of causing injury
Hazards
Diffuse reflectionsInvisible
Most dangerous procedure, contact your TA/Instructor
Eye injuries
Stray Beams
Beam Alignment
Biological Effects
Biological EffectsCornea
Focussing elementLens
Fine focusVitreous HumorRetina
Image is projected from the cornea and lensConnection to brain through optic nerve
FoveaSharp vision
Biological EffectsLaser Light 400-1400nm
Focussed beam on retinaAmplification of light by human eye: 10,000Extremely large irradiance Dependent on exposure time
Retinal Hazard Region
Thermal Effects
• Overheating• Retina burns• Invisible light: damage may only be detected post-injury• Severe damage may require surgery or transplant• Scars / blind spots in the field of vision• Depending on location of the burn, could permanently lose:• Central vision• Peripheral vision
Laser Hazards Control
• Wear laser safety glasses AT ALL TIMES
- Wavelength and Optical Density
• Remove wristwatches or reflective jewellery
• Close and lock the room door
• Place “Laser Work in Progress” warning sign on door
• If someone unexpectedly enters, turn laser off
• In case of an emergency, contact your TA/Instructor or UofT Campus Police 416-978-2222
• Return the laser controller key when completed
• Turn off laser when changing samples
Laser Hazards Control• Wear laser safety glasses AT ALL TIMES
- Wavelength and Optical Density
• Remove wristwatches or reflective jewellery
• Close and lock the room door
• Place “Laser Work in Progress” warning sign on door
• If someone unexpectedly enters, turn laser off
• In case of an emergency, contact your TA/Instructor or UofT Campus Police 416-978-2222
• Return the laser controller key when completed
• Turn off laser when changing samples
Questions?