Microscope Systems And Their Application in Machine Vision 1 1 Agenda • What is a microscope system? • Basic setup of a microscope • Differences to standard lenses • Parameters of microscope systems • Illumination options in a microscope setup • Special contrast enhancement techniques • Zoom components • Real-world examples What is a microscope systems? Greek: μικρός mikrós „small“; σκοπεῖν skopeín „observe“ Microscopes help us to look at small things, by enlarging them until we can see them with bare eyes or an image sensor. A microscope system is a system that consists of compatible components which can be combined into different configurations We only look at visible light microscopes We only look at digial microscopes no eyepiece but an image sensor in the object plane The optical magnification is ≥1 Basic setup of a microscope microscopes always show the same basic configuration: Sensor Tube lens: - Images onto the sensor - Defines the maximum sensor size Collimated beam path (infinity conjugated) Objective: - Images to infinity - Holds the system aperture - Defines the resolution of the system Object Differences to standard lenses microscope Finite-finite lens Sensor Sensor Collimated beam path (infinity conjugate) EnthältSystem apertureSystemblende Object Object Differences to standard lenses • Collimated beam path offers several options - Distance between objective and tube lens can be changed . Focusing by moving the objective without changing any optical parameter . Integration of filters, mirrors and beam splitters . Beam deflection with mirrors as needed . Integration of a zoom module for magnification variation - Parallel beams give better results with dichroic filters - Coaxial illumination can be integrated efficiently • Often more complex than finite-finite lenses Kenngrößen von microscope systems • Objective - Magnification: ratio of object and image size - NA (numerical aperture): defines the achievable resolution, comparable to f/# - Working distance: distance between object and objective - Object size (Field-of-View): defines what the sensor sees • Tube lens - Magnification: ratio of object and image size • System - System magnification = magnificationobjective x magnificationtube-lens - System magnification = focal lengthTube-lens / focal lengthobjective - Maximum Sensor size = Object size x system magnification Illumination options in a microscope setup Sensor • Brightfield illumination - coaxial brightfield illumination with beam splitter in the collimated regime - Köhler illumination possible optimum homogeneity • Dark field illumination - With ring light - Through-the-lens possible with central aperture • Backlight - Classic illumination in microscopy - Aperture of objective must be filled entirely Object Special contrast enhancement techniques Sensor • Polarisation - polariser and analyser under 90° to each other („crossed“) - Non-polarizing sample looks black analyser - Inspection of birefringent (optical anisotrope) material - Crystals - Plastics (birefringence) polariser Object Special contrast enhancement techniques Sensor • Differential Interference Contrast (DIC) Visualisation of different optical - analyser distances - Inspection of transparent materials - Inspection of glue - Pseudo-3D effect due to relief-like images polariser Nomarski image: conductive particles in Chip-on-Glass bond Prism Object Zoom-Components in Mikroscopes Zoom-components in collimated beam Sensor - Inifinity conjugate on both sides - Large zoom ratios possible (12.5:1) - Parfocal: object stays in focus during zooming Source: Wikipedia Object Real world examples 2 microscope systems by Qioptiq Optem Fusion mag.x system 125 Optimized for Maximum Flexibility Maximum image quality large FOV Resolution power ~3MPixel ~50MPixel Zoom Yes No Compatible to standard Yes No microscope objectives Parfocal distance 95mm 125mm Maximum Sensor size with 2/3“ 25mm Diagonal 1x Tube (11mm Diagonal) Autofocus Possible Available as standard components Real world example 1 Multispectral microscope with Zoom - 3 Spectral ranges by using dichroic beam splitters . 450…660nm . 670…780nm . 800…980nm - 7:1 Zoom ratio - Optical magnification 0.84x… 5.8x - Integrated manual focus Application: medical research Realized using Optem Fusion components Real world example 2 Differential Interference Contrast • Wide field microscope system mag.x 125 - Integrated DIC-Module - Rotating polarizer - 5mm FoV - Maximum 57mm sensor size - 50MPixel resolution power Image: Micro lens array R~2 mm, 300 µm pitch Last slide Thank you for listening In case of questions please don‘t hesitate to contact me..