introduction to experimental techniques in optics
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Introduction to Experimental Techniques in Optics. Motivation: Optics is becoming increasingly important in many application areas such as communication/computing and chemical/biological diagnostics. For most of these applications, the basic hardware and experimental techniques are similar. - PowerPoint PPT PresentationTRANSCRIPT
Introduction to Experimental Techniques in Optics
Motivation: Optics is becoming increasingly important in many application areas such as communication/computing and chemical/biological diagnostics. For most of these applications, the basic hardware and experimental techniques are similar.
Overview: This course will provide a hands-on introduction to these techniques. Lab skills are the main focus. Lectures will supplement.
Specific details:
• Start from scratch -- Build opto-electronic servo systems– laser intensity stabilization
– wavelength filter -- active control
• Break complex tasks into a series of simpler ones
Sample of material coveredExperimental techniques and capabilities
• Optics & mechanics– Optics handling– Mount assembly– Machining skills ?? – Cannot always buy what is needed
• Optoelectronics – Electronics skills – soldering, prototype boards– Circuit design – servos ?? – High sensitivity of optics often requires control– Interfaces – detectors, transducers
• Lab proficiency demonstrations • Lab book – important in real world
– Neatness not critical – will not count against– Completeness important
First pieces to make• Mirror mount post -- round
• Lens mount post =-- square
Interferometers
Beamsplitter Beamsplitter Mirror
Mirror
Inputs Outputs
Beamsplitter Mirror
Mirror
Input
Outputs
Mirror
Beamsplitter
Mirror Input Mirror
Outputs
Sanac -- Laser gyros for aircraft navigation
Michaelson -- FTIR spectrometers
Mach-Zender -- Modulators for fiber communications
Beamsplitter Mirror
Mirror
Input
Output
Output
Beamsplitter
Fabry-Perot -- Lasers and wavelength (ring version shown)
Entire servoLabels in bold are for connections or adjustments on the outside of the box
50K
50K
50K
Diff ampbalance> 50K
50KDC
reference100K
+15V
- 15V
Signal in
Reference in
100K
Diff ampgain100K
Diff ampoutput
DC refswitch
1 M
100
Lead100K
10 MIntegrator drift compensation
100K10 turns
+15V
- 15V
Integratoroutput
100
Lock/unlock switch
Rotary switch
0.1 F
10,000 pF
1,000 pF
100 pF
10 pF
20K
20K
20KDCinput100K
+15V
- 15V
Servooutput
20K
Modulationinput
1 M
Scan input
1 M
150
Servo box
• Put special-purpose electronics into fieldable box• Often done in R&D environment
Lab proficiency demos• Assemble mounts from “spare” parts
– basic machine shop skills– optics cleaning techniques
• Basic electronics– soldering techniques– construct and balance differential amplifier– construct and null integrator
• Construct interferometers– construct 4 types of interferometers– white light interferometer
• Construct and align opto-electronic system– photodiodes, PZTs, HV drivers
• Stabilize laser intensity using simple servo– acousto-optic shifters, VCOs
• Lock optical spectrum analyzer (Fabry-Perot) to laser– lock-in amplifiers and ac servos, etc.
• Construct servo box– design and packaging of special-purpose electronics
Lab books• Some are smart enough to make anything work on the first try• The rest of us have to be organized
Lab book is key to organization• Complex experiments:
– 1 day to take data– 1 day to analyze and update lab book
What goes in a lab book -- everything you need to reproduce results• Crude diagrams of experiment, circuit schematics, etc• Pin-outs and data sheets for opto-electronic components• Raw data --
– ex: as read off voltmeter or scope – copy of data traces (chart recorder trace, scope photo, computer image file)
• Processed data -- after computer fits, smoothing, etc• Equations and relevant theory• Narrative in your own words -- what was done, why, and what were results
Real world -- lab books can settle patent disputes, etc
Lab book sample -- Laser intensity servo• Similar to upcoming proficiency demo• Crude circuit diagrams• Note -- Pasted in sheets okay
Optical setupCircuit schematic
Effect of intensity servo on experiment• Attempt to reach shot noise in atomic clock experiment
Noise measurement Compare to shot noise theory
Lecture topics
• Basic experimental techniques including keeping a laboratory book and handling of optical components
• Optical mechanics and component mounting techniques • Passive optical components such as mirrors, lenses, and polarizers• Lasers – properties and operation• Coherence and interference effects• Basic electronics including op amps• Optical detectors and data collection• Active optical elements such as acousto-optics• Servos and transducers• Laser intensity stabilization• Lock-in amplifiers and ac servo techniques• Technical presentation skills
Possible supplemental topics
• Spectroscopy, FTIR
• Liquid crystal displays, optical memories & correlators
• Microscopy, confocal and fluorescence
• Photon counting and correlation
• Fiber optic techniques
Prerequisites & referencesPrerequisites: None• Include both beginning and advanced students• Disadvantage – Advanced students bored?, Beginning students overwhelmed?
Solution• Advanced students: Move at own pace -- proficiency exams• Beginning students: Extended lecture time or special lectures – questions and
answers
References
References: Optics by Eugene Hecht, Addison Wesley Pub. Co. • In print more than 20 years• Reads like series of complete lectures • Frees up more class time for lab work
Supplemental handouts/ web addresses
• Example: Manufacturer’s application notes
– http://www.newport.com/store/default.asp?lone=Optics<wo=Technical+Reference&lang=1
– http://www.cvilaser.com/Catalog.asp?filename=/bil-productindex-1221.asp
– http://www.mellesgriot.com/resourcelibrary/technicalnotes/default.asp
– http://www.newfocus.com/support/support_freelit.cfm
GradingGrading will be “bottom-line” oriented – Prepare to succeed in future job• Did you learn the material or not.
• Tests: 20% – Written – scheduled, based on lecture material
• Final exam: 20% – Optional – Can use test average as final exam grade
• Laboratory proficiency exams: 20%– Demonstrations of experimental proficiency – when ready
• Laboratory notebooks: 20%– Completeness first. – Neatness only in summaries. Nothing deducted for messiness elsewhere. – Will also be allowed during quizzes and proficiency demos
• Presentations: 20%– Present after completing core proficiency demons– Fellow students will also rate – Contributes to your grade– Presentations can have “dry runs” – not count toward grade
Course meeting timesLectures: MW 10:20 -- 11:10 am
Lab: F 10:20 am -- 1:10 pm, supplemental times ?
Problem: Limited space and equipment
Solution: Split into two groups
Homework: Everyone will have lab access
Lab books: Will supply