OPTI 380A Lab 3 - Detectors - slides-1

OPTI 380A Lab 3 - Detectors - slides-1 - OPTI 380A...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
1 OPTI 380A Intermediate Optics Lab 2: Detectors Tom Milster Professor, College of Optical Sciences, University of Arizona [email protected] edu [email protected] What is an Optical Detector? ! An optical detector produces an electrical signal that is proportional to the amount of light incident upon it. Input Light Detector (and maybe some circuits) Output Voltage or Current ! Optical detectors can be used to " Measure power in a laser beam; " Receive light from your TV remote in order to change channels; " Signal a police officer to pull you over in a speed trap that uses optical radar; and " Allow computer networks to connect to each other through optical fibers. 7/27/2010 OPTI380A - Lab 2: Detectors 2 ! We will NOT be discussing detector arrays, like charge- coupled devices (CCDs) and CMOS arrays used in your cell phone camera, although they work on similar principles.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Detectors Lab ! You will observe characteristics of four different types of optical detectors types of optical detectors. " Photodiode " Photoconductor " Photomultiplier tube (PMT) " Pyroelectric 7/27/2010 OPTI380A - Lab 2: Detectors 3 Photodiode (PN Junction) ! The photodiode is a PN junction (or PIN junction, which is similar) ! Instead of emitting light when current is pumped through the junction, like with an LED, the photodiode collects incident photons and generates a current (flow of electrons) from them and a current (flow of electrons) from them. Typical Symbol for PD: 7/27/2010 OPTI380A - Lab 2: Detectors 4 Typical symbol for LED:
Background image of page 2
3 Photodiode (PN Junction) ! When a light photon strikes a photodiode, an electron within the crystal structure becomes stimulated. If the light energy is greater than the band gap energy Eg, the electrons are pulled up into the conduction band, leaving holes in their place in the valence band. The electric field accelerates these electrons toward the N-layer and the holes toward the P- layer. Electron-hole pairs are generated in proportion to the amount of incident light are collected in the N- and P-layers. If an external circuit is connected between the P- and N-layers, electrons will flow away from the N-layer, and holes will flow away from the P-layer toward the opposite respective electrodes.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This document was uploaded on 10/30/2010.

Page1 / 9

OPTI 380A Lab 3 - Detectors - slides-1 - OPTI 380A...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online