1. EXPERIMENTAL OPTICS J.M. Saiz 2010

2. A course in English… Some disadvantages, but also: - Getting used to it (future Erasmus, courses and jobs) - Added value for your credits (enrich your CV) - Every help with the language whenever required - Science lecturers in other countries have not necessarily English as a mother language. Other issues: - Mixed groups with Erasmus students… if possible. - Technical vocabulary needs extra practice: so, practise! …but taught by Spanish lecturers. - Spanish phonetics, mistakes, etc: but courses are about Physics!

3. · There will be no ordinary Virtual Course · Course web-page: Start:www.optica.unican.eswww.optica.unican.es Clic :“Docencia” Clic :“Experimental Optics” · MATERIALS: Guides for the experiments (in English) The Course programme, callendar, etc. Examples of past evaluations Marks, when available This presentation …

6. Sessions organized in modules : Distribution THEORY: 1 modules during the first week REST: Modules for repetitions, personal work, optional or delayed experiments… Presentation : 1 Session EXPERIMENTS: 7 modules each group T R… S P, P, P, P P, P, P S P

7. Week 123456789101112131415 Date 17F24F3M10M17M24M31M14A21A28A5M12M20M19M26M Wednesday (4:30 a 7:30) P1 P2 P3a P3b P4 P5 P6 P7 Teoría G1 G2 - G1 G2 - G2 G1 - G2 G1 - G2 - G1 R - G1 - G2 S - G1 - R+VR+V R+VR+V R+VR+V R+VR+V R+VR+V Sessions organized in modules : Semester callendar R + V: Repetitions / Volunteered

8. Week 123456789101112131415 Date 17F24F3M10M17M24M31M14A21A28A5M12M20M19M26M Wednesday (4:30 a 7:30) P1 P2 P3a P3b P4 P5 P6 P7 THEORYTHEORY G1 G2 - G1 G2 - THEORYTHEORY G1 G2 - G1 - G2 - R G2 G1 - G2 - G1 - SEMINARSEMINAR THEORYTHEORY G1? G2? - G2? G1? Sessions organized in modules : Semester callendar

9. Laboratory Sessions: Work in groups: 2 students each group. Wednesday (16:30h – 19:30h) All groups Sessions organized in modules : Work Individual evaluation. Oral Presentations: In the Seminario de óptica (3 rd floor)

10. Experiments There will be 6 experiments in 7 sessions. plus another optional. The experiment must be prepared beforehand. A careful reading is enough, most of times. On arrival to the lab, you are going to be asked about the purpose of the experiment Additional experiments are optional.

11. Oral Presentation Individual (15 min, aprox.). Some hints: -Briefly Describe the objetive and the work -Show results and comments. -Remarks about what is interesting, too difficult, etc. -Suggestions -Freedom for other squemes, historic introductions… Students receive questions (5-10 min) The student making the presentation is evaluated, and also others taking part in the discussions (positive evaluations) Attendance compulsory for the evaluación continua system Experiments chosen by the students should be different from each other as long as it is possible.

12. April 21 st, Wednesday Oral Presentation. Date

13. How is the mark assessed? Experiment quality. (A draft summary is handed to the supervisor AND a laboratory notebook is kept by each student Oral Presentation (15%) 1 report (chosen by the student),  7 pages) (15%) Exam (Easy!): (30%) Nombre... Grupo... Fecha... Preguntas, Realización y Resultados: Questions and communication during the experiment (40%)

14. Notebook, presentation, report, exam… The presentation should be understood by somebody who hasn’t performed the experiment. There is not a mandatory esqueme, but it should reasonably introduce the subject, explain the development and main results, and include a discussion. The notebook is a personal account of what is done in the lab. A separate summary containing only the measurements and the main results must always be handed to the supervising person. (Sometimes error calculations may be given later)

15. Notebook, presentation, report, exam… The report should follow some standard squeme, for instance that containing a summary, an introduction, the results and a discussion. A good suggestion is to include the answers to the questions proposed in the guidelines of the experiments. This report should look like the one you would like to present after finishing the lab work if you had enough time. A maximum of 7 pages is proposed, to avoid lengthy works. The experiment chosen for the report should be different to that of the oral presentation. The exam contains 4 or 5 questions about the development of the experiments. Some examples ot these questions can be found in the web of the course Técnicas Experimentales-4, which link is next to this.

16. Supervisors José Mª Saiz (coordinator) Fernando Moreno

17. Next… A description of the experiments - Not complete! - Not to substitute the work with the experiments guide - The lab is the best place to understand the experiments, but… - …some procedures and ideas are easier in the classroom.

18. Experiment N.1 HH´ F F´   OO´ aa´  z´ z f´ f Find out the principal planes and the focal planes H, H’ F, F’ f, f ’ -Because of the object points chosen to apply the procedure we shall find ALSO the position of the first and last diopters, and the thickness of the lens. - From our measurements we will assess f ’ y FF’ 1.- We must align the system 2.- We need to produce a collimated beam 3.- We shall measure a complete set of points on the optical bench

19. HH´ F F´   OO´ aa´  z´ z f´ f Fig.1. Correspondence equations connect object and image positions for a system of given focal length. The origin may be taken either in the principal planes (positions a, a´) or in the focci F, F’,(positions z, z´). In this experiment we shall use the latter. z · z’ = - f´ 2 -(1/a) + (1/a´) = (1/f´) Point- like source Source Collimating Lens Unknown system Microscope T T L Alignment: Experiment N.1

20. HH´ F F´   O1O1 z1z1 O1´O1´  z´ 1 LIGHT | z´ 1 | In order to measure z 1 we need to observe the other side…... ¡or better turn the lens! x1x1 x3x3

21. Experiment N.1 HH´ F F´   O1O1 G z1z1 O1´O1´  z´ 1 H´H O2O2 O2´O2´  F´  F  G O2O2  z2z2 z´ 2 O1O1  LIGHT | z 1 | f´ x’ 1 x’ 2

22. Experiment N.1 HH´ F F´   O1O1 G z1z1 O1´O1´  z´ 1 H´H O2O2 O2´O2´  F´  F  G O2O2  z2z2 z´ 2 O1O1  LIGHT x4x4 FF´ f´ HH´

23. Experiment N.2 2d2d  2d sen  = k Part 1) For a given (known)   We measure  and calculate d. Part 2) For another  (unknown)  We measure  and calculate (using d )

24. Experiment N.2: Preparing the Goniometer Angular Scale (1’ resolution nonius) T1T1 T2T2 T3T3 Collimating arm Telescope arm Platform Source [Na lamp] Slit 1 st ) Place the reference (cross) with a vertical line. It is placed in the intermediate image. 3 rd ) Place the focal points of the telescope to infinity shifting the eyepiece with the lateral wheel. We shall use an external collimator for this. 2 nd ) Place the eyepiece in its frame so that the cross is seen sharply. TELESCOPE ARM:

25. Experiment N.2: Preparing the Goniometer Angular Scale (1’ resolution nonius) T1T1 T2T2 T3T3 Collimating arm Platform Source (Na lamp) Slit 1º) Put the telescope arm in front of the collimator (removing the platform) 3º) Adjust the collimator wheel till we can see a sharp image of the slit 2º) Observe the slit through the telescope arm COLIMATOR: 4º) Vary the slit width (as narrow as possible but still bright) + LEVEL THE PLATFORM: T 1, T 2 y T 3 + ALIGN OBJECT (IF NECESSARY) Telescope arm

26. Angles are measured by taking differences Angular scale: There is a sexagesimal Vernier Alignment of the grating: same  at both sides 2d2d  Fixed scale 0 10 20 30 Travelling scale In 0.5° steps Accuracy: 1’ Experiment N.2: Preparing the Goniometer

27. [Symmetry in the observation]

28.  can be either measured or given ( with an error ±1´) Basis of the method: Refraction law     ´´ ´´ n Fig.1: Refraction of a collimated beam (represented by a single ray) in the flat faces of a glass prism.  is the main angle of the prism, the diedric angle, and  is the total deviation, that shows a minimum,  m.  m and the index n are connected: Experiment N.3. Refraction index measurement: using a prism Prepare the goniometer

29. 3 4 2 1 5 6 7 8 9 10 11 Abbe’s refractometer Experiment N.3. Using a refractometer Fig.3: Border line separating the bright and dark regions. The origin is the critical angle when passing from a dense media (bottom prism) to other less dense (liquid of unknown index). The instrument uses an extense source, but the effect is already clear by representing a point source. Liquid of Unknown index Source Eye Right eyepiece Intermediate Focal Plane Collecting Lens High-index Prisms

30. Resulting curve is checked with the value obtained before (Yellow) We measure n for two lines (two ): Red and Green in Na lamp Simplified Cauchy’s disperssion formulae n( ) = A + B / 2 From the analytical curve, an estimate of the Abbe number can be made: V = Experiment N3. Part b: Disperssion

31. Fig. 1 Scheme of the measuring system. (Points 1 to 7 are inside the monochromator instrument) 1.- Source 2.- Lenses 3.- Mirror 4.- Entrance slit 5.- Reflection diffracton grating. (BASIC DISPERSION COMPONENT OF THE MONOCHROMATOR) 6.- Wavelength adjustment wheel 7.- Output slit 8.- Color filter 9.-Photodetector 10.- Power source (V-constant) for the detection circuit 11.- Voltimeter 12.- Controlling computer. 2 3 4 2 5 6 7 8 9 11 12 1 10 Experiment N4: Color Filters

32. Fig. 2 Detection System. (Items 9 to 12 in the scheme of Fig.1) (*) Only if connected with a data acquisition system. VsVs F + V 10 K  (*) T 0 1 Experiment N4: Color Filters

33. Figura 1. LEFT: Set-up for the interference fringes experiment with Fresnel’s biprism: upper view. S is the source (slit); S 1 and S 2 are the positions of the virtual slits (the distance between them is of the order of a fraction of- to a few mm, though in the scheme is made artificially large for the sake of clarity. Darkened area is the superposition region, where fringes can be observed on a screen, for instance , located inside that region. CENTER: Detail of the interference construction in the center of the screen: Wavefronts coming from S 1 and S 2 are separated /2. Black and hollow dots stand respectively for constructive and destructive superposition, therefore producing an irradiance variation distributed in lines, known as interference fringes (RIGHT) d S1S1 S2S2 S D   y Experiment N5: Interferences

34. d may be difficult to measure… directly Error: Calculating : The plane  is observed with an eyepiece.  Experiment N5: Interferences

35.  E E E cos  E sen  E cos  E sen  Fig.2 Linearly polarized beam through a “ /4” wave plate. The result is a centered elllipse. Fig. 3 Sequence of elements on the bench for the realization of the experiment Lámp Polarizer Collimating arm of the goniometer Diaphragm “ /4” Analizer Photodetector Meter Experiment N6: Polarized beams

36. Fig.1 Description of the situation in which no light is observed as reflected from the prism. This is a combined effect of: a) The incident polarization given by polarizer P (that must be parallel to the plane of incidence) – plane of the screen in this drawing. b) The angle of incidence  (that must be the Brewster angle   ). Source P Prism n No reflected light!  Collimator ¿How do we measure the elipticity of an elliptically polarized beam? Experimental point: the “zero” of the detector. Coarse and fine adjust Experiment N6: Polarized beams

37. Fig.1 Image capturing system. Images are formed on a bright screen. MATERIALS CCD camera + Objective lens. Control PC + Digitalizer card. Post + travelling holder + adapter Extended source Opaque discs of the same size Auxiliary objects, coins, discs, etc Experiment N7: Digital Images

38.  First Objective. Get familiar with some basic operations:  Image Capturing  Study Single Points Of An image  Obtain And Understand Grey Histograms  Make Simple Operations On An Image  Make Operations Between Different Images  Second Objective. Apply the basic operations to some functions on images: 1) Check the degree of homogeneity of an extended source. 2) Count the objects in the captured image. 3) Dettect movement and measure its magnitude. Experiment N7: Digital Images