Dimensional Measurement using Vision Systems - NPL Publications ...

3.1.3 Fluorescent tubes...............................................................................31
3.1.4 LED lighting .......................................................................................31
3.1.5 Lasers...................................................................................................31
3.2 ILLUMINATION CONFIGURATIONS.....................................................31
3.2.1 Diffuse front lighting ........................................................................32
3.2.2 Directional front lighting..................................................................32
3.2.3 Ring lighting.......................................................................................33
4 LENS CONFIGURATIONS FOR MACROSCOPIC SYSTEMS ............................34
4.1 OPTICAL PRINCIPLES................................................................................34
4.1.1 The F-number.....................................................................................34
4.1.2 Thin lens formulae ............................................................................35
4.1.3 Depth of field .....................................................................................37
4.2 MODUATION TRANSFER FUNCTION...................................................40
4.3 ABERRATIONS IN THE IMAGE FORMING SYSTEM ..........................40
4.4 LENS SELECTION ........................................................................................41
4.5 COMMERCIAL LENSES ..............................................................................42
4.5.1 Standard lenses ..................................................................................42
4.5.2 High resolution lenses ......................................................................42
4.5.3 Macro lenses.......................................................................................42
4.5.4 Telecentric lenses...............................................................................42
5 CAMERAS .....................................................................................................................42
5.1 LINEARITY ....................................................................................................43
5.2 DATA TRANSMISSION ..............................................................................43
5.3 ANALOGUE CAMERAS .............................................................................44
5.3.1 Interlaced (or synchronous) cameras..............................................44
5.3.2 Progressive scan cameras .................................................................44
5.3.3 Asynchronous cameras.....................................................................44
5.4 DIGITAL CAMERAS ....................................................................................45
5.5 LINESCAN CAMERAS................................................................................45
6 FRAME GRABBERS....................................................................................................45
6.1 ANALOGUE FRAME GRABBERS .............................................................45
6.1.1 Live mode ...........................................................................................46
6.1.2 Acquisition mode ..............................................................................46
6.1.3 Use with a standard video camera..................................................46
6.1.4 Use with a progressive scan camera...............................................46
6.1.5 Use with an asynchronous camera .................................................46
6.1.6 Use with a line scan camera.............................................................46
6.2 DIGITAL FRAME GRABBERS....................................................................47