3.2 Course outline

1. Imaging 2.1 Light propagation across interfaces 2.2 Photography and optical 2.3 Aberrations 2.4 Plane parallel plates and reflective prisms 2.5 Depth of focus Optical Engineering 2.6 Magnifying glass and basic microscope 2.7 Modern microscopes 2.8 Beam expansion 2.9 Martina Gerken 15.11.2007 2.10 Optic design 2. Optical sensors 3. Optics in data storage 4. Introduction to displays 5. Fourier optics 6. Diffractive optics and holograms 7. Integrated optics Universität Karlsruhe (TH) 8. Computerized imaging

3.3 3.4 Exercise Magnification

• Evaluate the following optical systems to obtain an upright, magnified image • Generation of upright, magnified image of an LED chip at a given distance!

Object Magnifi- Group 1 Lens distance Lens 2 distance cation Lens 1 Lens 2 20 mm 40 mm 1 25 mm 117 mm 6x B2 (planoconvex) (planoconvex) 15 mm 60 mm 2 25 mm 155 mm 2.5x G1 (planoconvex) (biconvex)

16 mm 60 mm B1 3 30 mm (combined 165 mm (combined 2.5x convex) convex) f1 f2 10 mm 60 mm b 4 16 mm 125 mm 5x g1 b1 g2 2 (biconvex) (planoconvex)

25 mm 60 mm 5 26 mm 177 mm 5x (convex) (convex)

• Suggest an improved system! 3.5 3.6 2-stage imaging with scattering screen 2-stage imaging with field lens

• For 2-stage imaging with only two lenses second lens needs to be large to • For 2-stage imaging with only two lenses second lens needs to be large to capture light from all object points capture light from all object points • Solution 1: Include scattering screen • Solution 2: Include field lens at position of intermediate image – Image of entire object – Entire object visible in bright image – Image dark as light scattered in all directions – Disadvantage: dirt on field lens is also imaged

Object Intermediate image Image

Losses

Object Intermediate image + field lens Image

Object Intermediate image Image + scattering screen Source: Schröder/Treiber, Technische Optik Source: Schröder/Treiber, Technische Optik

3.7 3.8 Magnifying glass – Calculation of magnification Microscope – Calculation of magnification

• For unstrained viewing, eye adapted to infinity and intermediate image at focal • For unstrained viewing, object at single and eye adapted to infinity length of ocular • Tube length is distance between focal plane of objective and focal plane of ocular (typical value 20 cm) Objective Ocular G Lens Lens α0

a G’ s a G α G Intermediate Α α f a image M = M = = s G f f t („Tube length“) f f α0 f Objective Objective Ocular Ocular Lens as

G' t + fObj ⎛ 1 1 ⎞ t G M = = = ()t + f ⎜ − ⎟ = obj Obj ⎜ ⎟ G a fObj t + fObj fObj αΑ ⎝ ⎠ Object

t as M tot = M obj M ocu = f f fObj fOcu 3.9 3.10 Oculars Course outline

• Ocular combines field lens and eye lens 1. Imaging optics • Modern microscopes mostly use positive oculars, i.e., oculars forming real 2.1 Light propagation across interfaces image 2.2 Photography and optical lenses – For negative oculars with virtual image it is not possible to include markers 2.3 Aberrations and image is not delimited well 2.4 Plane parallel plates and reflective prisms 2.5 Depth of focus 2.6 Magnifying glass and basic microscope 2.7 Modern microscopes 2.8 Beam expansion 2.9 Telescopes 2.10 Optic design 2. Optical sensors 3. Optics in data storage 4. Introduction to displays 5. Fourier optics 6. Diffractive optics and holograms 7. Integrated optics 8. Computerized imaging Source: Schröder/Treiber, Technische Optik

3.11 3.12 Exercise: Beam expansion Basic beam expansion systems

• To achieve high resolution many imaging systems employ beam expansion • Beam expansion systems are telescopes! – Minimum resolvable angle: • Two basic principles λ ∆φmin = 1.22 [rad] Galilei- D

• Principle: Collimated beam is transformed to collimated beam with larger diameter

• Design the optics for a 2-lens beam expansion system! • Build your beam expansion system! Objective Optical axis Beam path • Characterize your beam expansion system! – Focal lengths and diameter of lenses – Distance between lenses – Final beam diameter D – Losses – Expansion ratio • Calculate the minimum resolvable angle! Kepler-telescope –2π rad = 360°; 1° = 60′ (Arc minutes); 1′ = 60″ (Arc seconds) Source: http://de.wikipedia.org/ 3.13 3.14 Course outline Kepler-Telescope

1. Imaging optics • Goal: Magnicifaction of distant objects 2.1 Light propagation across interfaces • Most telescopes are afocal systems: Object at negative infinity is imaged to positive infinity 2.2 Photography and optical lenses • Focal points of objective and ocular at same position 2.3 Aberrations 2.4 Plane parallel plates and reflective prisms 2.5 Depth of focus 2.6 Magnifying glass and basic microscope 2.7 Modern microscopes 2.8 Beam expansion 2.9 Telescopes 2.10 Optic design 2. Optical sensors f f 3. Optics in data storage Objective Ocular 4. Introduction to displays Source: http://de.wikipedia.org/ 5. Fourier optics 6. Diffractive optics and holograms fObjektiv 7. Integrated optics • Magnification given by: M = 8. Computerized imaging fOkular

3.15 3.16 Telescope: Refractor Telescope: Reflector

• Kepler telescope • Newton-telescope – Combination of two convex lenses – Parabolic main mirror to correct for – Correction of : Use of additional concave lens – Limited field of view due to aberrations for oblique incidence angles (achromatic objective) – Second mirror reduces resolution due to diffraction

Convex lens Secondary mirror Concave lens

Ocular Primary mirror 3.17 3.18 Terrestrial telescopes Which Christmas present?

• BRASKO 60700 telescope • For observation of terrestrial objects often upright image is desired • “High quality refractor-telescope with many extras” – May be obtained by additional lens or prism system Includes equipment for terrestrial observation (Umkehrlinse), moon filter, Barlow-lens, stable mount with tray, holder of oculars and much more. – Focal length 700 mm – Objective-diameter 60 mm – Maximum resolution 525x – Price: EUR 99,95

Source: http://www.amazon.de

3.19 3.20 Which Christmas present? Compilation of questions

• Bresser telescope Pluto 114/500 • Lay out a 2-stage magnification system with an upright image! • “Large Newton reflector telescope in compact layout. For observations • What is the function of a field lens? within and outside our solar system” • Where is the field lens placed in an optical system? – Focal length 500 mm • Calculate the magnification of a magnifying glass with a 62,5 mm focal length – Objective / Mirror ø114 mm lens! – Maximum magnification 25x - 250x • Sketch an optical system to achieve beam expansion! – Price: 134,00 € • Derive the magnification of a Kepler telescope!

• Decide until next Thursday which telescope you buy and list your arguments!

Source: http://www.das-fernglas.de