1 Optical instrument 光學儀器

2 Real images 實像 projected on a screenImages can be projected on a screen. E.g. What you see on the screen right now is a real image.

3 Virtual image 虛像 Images can’t be projected on a screen. E.g.. Image produced by magnifying glass ( 放大鏡 ) images produced by spectacles for long-sight ( 遠視 ) Important!!!!Important!!!! both real and virtual images can be seen by human eyes.

4 Rotation of plane mirror through  Reflected ray rotate by 2 

5 Moving the plane mirror though x M2 M1

6 Convex lens 凸透鏡 ( 透鏡 Convex lens 凸透鏡 (Converging lens 會聚透鏡 )

7 Images of convex lens

8 real or virtual imageDepending on the position of object, either real or virtual image can be produced. Real image  inverted 倒立 Virtual image  upright 直立

9 Concave lens 凹透鏡 (diverging lens 發散透鏡 )

10 Linear magnification, m 線性放大率 m = h’/ h = v / u m = h’/ h = v / u

11 Visual angle 視角, 

12 Angular magnification 角放大率, M  i = Visual angle of the image  o = Visual angle of the object

13 Lens/Mirror formula 成像 ( 透鏡 ) 公式

14 Magnifying glass 放大鏡 Just a piece of convex lens 凸透鏡

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16 D = 25 cm

17 DLeast distance of distinct vision 最小明視距離 D:Least distance of distinct vision 最小明視距離 D =D = Least distance of distinct vision, near point ( 近點 ) or the distance of the near point ( 近點 ) from the eye. D = 25 cmD = 25 cm. normal adjustment ( 正常調校 ).When the image is formed at the near point, a magnifying glass is said to be in normal adjustment ( 正常調校 ).

18 Use of magnifying glass : 0 < u < fUse of magnifying glass : 0 < u < f Virtual image is formedVirtual image is formed Enlarged and uprightEnlarged and upright

19 Magnification of magnifying glass NORMAL ADJUSTMENT 正常調校 (image at D):    tan  = h / D(without magnifying glass) u = Df / ( D + f )By, u = Df / ( D + f )  u  = h / u = [h ( D + f )] / Df Angular magnification M:  M =  /  = ( D + f ) / f = ( D / f ) + 1

20 Image at infinity 無窮遠處 Image at infinity 無窮遠處, v = , u = f : (This situation is not the case shown in the figure)  = h / f  = h / D M =  /  = D / f

21 AL MC 01-16

22 AL MC 00-20

23 AL MC 99-10

24 AL MC 97-18

25 Compound microscope 複式顯微鏡

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27 Objective: short f o 物鏡焦距 Eyepiece: long f e 目鏡焦距, f o < f e Separation of the lenses > f o + f e 2f o > u > f oTo the objective lens: 2f o > u > f o Image formed by objective lens is real (enlarged & inverted). The real image 真像 produced by objective lens is the “object 物 ” for the eyepiece lens f e > u’ > 0To the eyepiece lens: f e > u’ > 0

28 enlarged virtual image at DAn enlarged virtual image is produced by the eyepiece lens at D.( in normal adjustment) Eyepiece works as an magnifying glass Angular magnification M M =  /  = ( h 2 / D )/( h / D) = h 2 / h = ( h 2 / h 1 ) ( h 1 / h ) m e m o = m e m o = (eyepiece linear mag.) x (objective linear mag.)  = h / D  = h 2 / D

29 Refracting telescope 折射式望遠鏡

30 

31 focus 焦點 of the objective eyepiecesame pointThe focus 焦點 of the objective and that of the eyepiece are at the same point. Separation of the lenses = f o + f e f o > f e image of distant object focal plane 焦平面 of the objective “object”eyepiece.The image of distant object is formed at the focal plane 焦平面 of the objective. This is the “object” for the eyepiece. eyepiecevirtual image infinityThen the eyepiece form an virtual image at infinity.

32 Without telescope,  = h / f o   tan  = h / f e Angular magnification M M =  /  = f o / f e, f o > f e

33 Eye ring 出射光瞳 : image of objective P formed by eyepiece Q

34 Eye ring most light enters the eye.Eye ring is the position of the eye, when using an optical instrument, at which most light enters the eye. best position of the eye light intensity is the greatestMost stars viewed by astronomical telescopes are fainted. The intensity of the final image is further confined by the aperture of the objective. The best position of the eye is where the light intensity is the greatest. (eye ring)

35 AL MC 99-11

36 Grating spectrometer 光柵光譜議

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38 For spectral analysis ( 光譜分析 )For spectral analysis ( 光譜分析 ) Measure angular displacement accuratelyMeasure angular displacement accurately 3 components:3 components: collimator 準直管 turntable 轉盤 (with grating 光柵 ) telescope 望遠鏡

39 Collimator:produces a parallel beam of light from the source diffraction grating scale in degreeTurntable:with diffraction grating,can be rotated, the edge of the table has a scale in degree Telescope:can be rotated, measure angle of deviation of light through the grating [receive parallel beam of light]

40 Adjustment before experiment TelescopeTelescope: ready to receive parallel light. view a distant object and then adjust the eyepiece until the image is focused at eh cross wire. collimatorcollimator: (without grating) produces parallel light. (without grating) aligning the telescope with the collimator and then adjusting the position of the slit until the image of the slit is focused at the cross-wire.

41 TurntableTurntable: adjusted to horizontal by spirit level and the 3 leveling screws underneath mount the grating Lastly, mount the grating on the horizontal turntable. each line of the spectrum can be located accurately (angle) By turning the telescope, each line of the spectrum can be located accurately (angle).