Team: Maryam Badakhshi, Shannon O’Keefe, Laura Poloni, Hasmita Singh

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

1. Introduction

Experiment Context --Presentation Currently, the Advanced Physics lab courses do not have a presentation component that gives information on the lab to the students This presentation component is meant to be introduced to the students by the professor or TA of the course, in advance to the experiment

Experiment Context --Students The main purpose of this presentations is to give some general information alongside with application for the experiment, the students can use this information to choose the experiment they plan on doing Furthermore, this presentation will acquaint students with laboratory concepts, the equipment, and the safety procedure needed to be considered to use this equipment

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)

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 Characteristics 980 nm  Infrared range 330mW maximum power Collimated beam Class 3B laser

Laser Classification Class 3B Laser Safety Interlocks 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 reflections Invisible Most dangerous procedure, contact your TA/Instructor Eye injuries Stray Beams Beam Alignment 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

Biological Effects Laser Light nm Focussed beam on retina Amplification of light by human eye: 10,000 Extremely 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 Return the laser controller key when completed Turn off laser when changing samples