Introduction to Experimental Techniques in Optics

1. 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

2. Sample of material covered Experimental 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

3. First pieces to make • Mirror mount post -- round • Lens mount post =-- square

4. Mirror Beamsplitter Beamsplitter Outputs Inputs Mirror Input Mirror Beamsplitter Outputs Mirror Mirror Input Mirror Beamsplitter Outputs Mirror Input Beamsplitter Beamsplitter Output Output Mirror Interferometers Mach-Zender -- Modulators for fiber communications Michaelson -- FTIR spectrometers Sanac -- Laser gyros for aircraft navigation Mirror Fabry-Perot -- Lasers and wavelength (ring version shown)

5. Entire servo Labels in bold are for connections or adjustments on the outside of the box Lock/unlock switch Rotary switch 10 pF 100 pF +15V 1,000 pF Lead 100K 10,000 pF 10 M Integrator drift compensation 100K 10 turns 50K 0.1 mF 20K 1 M 100 W 50K Modulation input - 15V Signal in 100K 1 M 50K 20K 150 W Reference in 100W Diff amp gain 100K 1 M Servo output Scan input Diff amp balance > 50K +15V Integrator output 50K +15V 20K DC reference 100K 20K DC ref switch DC input 100K Diff amp output - 15V - 15V

6. Servo box • Put special-purpose electronics into fieldable box • Often done in R&D environment

7. 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

8. 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

9. Lab book sample -- Laser intensity servo • Similar to upcoming proficiency demo • Crude circuit diagrams • Note -- Pasted in sheets okay Optical setup Circuit schematic

10. Effect of intensity servo on experiment Noise measurement Compare to shot noise theory • Attempt to reach shot noise in atomic clock experiment

11. 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

12. Possible supplemental topics • Spectroscopy, FTIR • Liquid crystal displays, optical memories & correlators • Microscopy, confocal and fluorescence • Photon counting and correlation • Fiber optic techniques

13. Prerequisites & references Prerequisites: 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

14. 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&ltwo=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

15. Grading Grading 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

16. Course meeting times Lectures: 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