Lenses                                                                                                                    ...
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Ch1sum

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Ch1sum

  1. 1. Lenses Information storage before the lens + Curvature added by lens Curvature of light after lens = Curvature Image Manipulation Curvature added = 1/f In computers voltages are stored: Greyscale Image 256 shades of grey Dioptres (D) Voltage either ON or OFF 106 pixels per image 1 0 Smoothing Sharp edges 1 pixel needs 1 byte Lens Formula: Binary Numbers: 24 23 22 21 20 Rule: Replace Memory needed = 1 million bytes each value by the 1=1+1 1 1 0 1 1 Total = 27 (1MB) mean of its value v u f and those of No. of alternatives 16 8 0 2 1 Colour needs 3 bytes per pixel surrounding 256 = all letters = capitals + symbols, no. 1-9 pixels. m = v/u (magnification) I = amount of information (No. of BITS) u = - number 0-255 Number of alternatives = 2I eg I = 8 = (1 Removing noise byte) No. of alternatives = 28 = 256 Replace each pixel 27 26 25 24 23 22 21 20 by the median of 1 extra bit doubles the no. of its value and the 1 1 1 1 1 1 1 1 alternatives. surrounding pixel Chapter 1 values. Imaging Scanning Tunnelling Microscope Support and control and Finding Edges Wavelength (m) control arm scans in zig- Speed (m/s) zags across surface -1 Ultra sharp needle point -1 +4 -1 -1 v = fλ Atoms in material Subtract the N, S, E and W pixel values from Time period of Frequency (Hz) 4 times the value of each pixel. a wave (sec) • Tip is close to atoms electrons tunnel across gap 1 Numbers can be Resolution: smallest detail T = /f electric current between surface and tip • Tip moved up and down keeping tunnelling current manipulated distinguishable, size of one constant. • The movements of tip are recorded Darker Region - larger number Set of numbers 1 number = Picture element (Pixel)

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