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Optical Tweezers

Optical Tweezers

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Optical Tweezers

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Presentation Transcript

  1. Optical Tweezers Team: MaryamBadakhshi, Shannon O’Keefe, Laura Poloni, Hasmita Singh

  2. Overview • 1) Introduction • 2) Background & Applications • 3) Apparatus • 4) Laser Safety

  3. 1. Introduction

  4. Experiment Context --Presentation • No presentation component available in the Advanced Physics Labs courses • This presentation component is meant to be introduced to the students by the professor or TA of the course, in advance to the experiment

  5. Experiment Context --Students • Main purpose: • Give general information about the experiment and apparatus • Applications for the apparatus • Students may use this presentation to choose their experiment • Also to acquaint students with laboratory concepts, the equipment, and the safety procedure

  6. Relevant Courses • This experiment is based on knowledge of Energy Equipartition theory that may be related to back ground courses in both Engineering and Arts and Sciences : • Phy293 Engineering • PHY256H1  Arts and Science • This lab may also be used in the following courses: • PHY424/426/428/429 (A&S) and PHY327/427/428/429 (Engineering)

  7. Experiment Learning Objectives • Students will have the opportunity to : • Work on interesting and challenging experiments • Deepen their understanding of the underlying Physics • Further develop laboratory, analysis and communication skills • This presentation introduces the Optical Trapping apparatus and the many interesting applications of it

  8. 2. Background & Applications

  9. Manipulation of Nanowires • Four spheres trapped and rotated by linearly scanning with laser light (Tong et. al., Nano Letters, 2010) (Nam et. al., IJPEM, 2009) • Alignment and rotation of a silver nanowire

  10. Isolation and Visualization of DNA Staining with Fluorescent Dye Force-Extension analysis of the trapped DNA “Catching” a Single DNA Molecule Trapping of two beads (Gross et. al., Methods in Enzymology, 2010) (Gross et. al., Methods in Enzymology, 2010) Protein-coated DNA region Fluctuations in DNA molecule

  11. 3. Apparatus

  12. MainComponents Very Dangerous! Safe!

  13. 4. Laser Safety

  14. Optical Trap Laser Characteristics • 980 nm  Infrared range • 330mW maximum power • Collimated beam • Class 3B laser

  15. Laser Classification • Considered incapable of causing injury • Hazardous under direct and specular reflection, but not diffuse reflection • Direct exposure to beam is an eye hazard • Maximum power 500mW

  16. Hazards • Diffuse reflections • Invisible • Most dangerous procedure, contact your TA/Instructor • Eye injuries Stray Beams Beam Alignment Biological Effects

  17. Biological Effects • Cornea • Focussing element • Lens • Fine focus • Vitreous Humor • Retina • Image is projected from the cornea and lens • Connection to brain through optic nerve • Fovea • Sharp vision

  18. Biological Effects Retinal Hazard Region • Laser Light 400-1400nm • Focussed beam on retina • Amplification of light by human eye: 10,000 • Extremely large irradiance • Dependent on exposure time 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

  19. Laser Hazards Control • Place “Laser Work in Progress” warning sign on door • Close and lock the room door • Remove wristwatches or reflective jewellery • Wear laser safety glasses AT ALL TIMES • - Wavelength and Optical Density • If someone unexpectedly enters, turn laser off • Turn off laser when changing samples • Return the laser controller key when completed • In case of an emergency, contact your TA/Instructor or UofT Campus Police 416-978-2222

  20. Questions?