Optical Spectroscopy with dispersive Spectrometers
Basics - Building Blocks - Systems - Applications

Basics 5: Illumination of and with Spectrometers
 Light Sources – Fibre Optics – Transfer Systems – Radiometry.
 

Please note: The content of the BASICS pages is available in extended, printed shape since June 2014:
 

"Fundamentals of dispersive optical Spectroscopy Systems",
SPIE-Monograph, ISBN No.: 9780819498243

The internet pages have been reduced to the headlines, equations, and figures of the different chapters . We hope, that the brief collection and the complete and extended book will be as helpful and useful for you, as the spectra-magic.de/Basics have been.

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1.0.0 Fundamentals
Aim of the “Fundamentals” is to help starters with the definition and verification of the instrumentation for optical spectroscopy. Experienced spectroscopists and expert physicists will know some of the issues better and in deeper detail. But hopefully, every reader may find things worth mentioning.


5.0.1 Energy and Power of Optical Signals
Graph 109 - Ralation nm / energy
Graph 109:
displays the power of a single photon vs the wavelength.

5.0.2 The different Emission Characteristics of Light Sources, and the Principles of Collection
Light sources do emit in very different kinds, thus special techniques of collection are required.
 graph 110: several kinds of light collection

Graph 110
: The most important emission characteristics of light sources

5.0.3 Definition of Radiation, Parameters and Nomenclature
Graph 110B - Radiometric Defintions
Radiometric Nomenclature and Parameters, Description:


5.1 The different Types of Radiation, and their Collection

5.1.1 Laser Radiation
Graph 111A - Laser Beam Profiles
Graph 111A
: Four typical far field laser images
Graph 111B - two typical Laser spectrometers
Graph 111B
: Laser-internal normal incidence and grazing incidence spectrometer

Graph 112 - collection of Laser light
Graph 112
: shows two of the options of Laser beam transfer.

5.1.2 Cone-shaped Radiation
Graph 113 - collection of Cone-shaped light
Graph 113
shows two ways of the transfer of cone shaped light.

5.1.3 Ball-shaped Radiation from Point Sources: Lamps
Graph 114 - Collection of light from lamps
Graph 114: Ways to collect ball shaped radiation and illuminate a spectrometer.

Graph 115 - Lamp versions
Graph 115: the most popular wide band radiators used in optical spectroscopy:
Graph 116  - Emission curves of 4 lamps
Graph 116
: Typical, simplified spectra of Deuterium (purple curve, D2), Tungsten Halogen (red curve, HLX) and Xenon

5.1.3.4 Light Collection and Transfer into a Spectrometer.

5.1.4 Diffuse Radiation, collected by integrating Spheres
Graph 117 - Integrating spheres
Graph 117
: Two typical applications of integrating spheres in optical spectroscopy.
 Graph 118 Efficiencies of sphere coatings
Graph 118
: Efficiency curves of popular coatings for integrating spheres
Graph 119 - Sphere equations
Graph 119
covers the equations required with graphical support.

5.1.4.2 The Collection of Lamp Radiation.
Graph 120 - Sphere illumination
Graph 120
proposes a solution of efficient light collection from large and hot lamps.

5.1.4.3 Approaching the Design of a Sphere

5.1.5 NIR Radiation

Graph 121 - NIR sources -  Emission vs Temerature
Graph 121
: Radiance of thermal sources in the NIR at filament temperatures between 1300°C and 2927°C.

5.1.6 IR Radiators

Graph 122A - IR Radiance - Emission vs Temerature - lin mode Graph 122B - IR sources -  emission vs temperature  - log mode
Graph 122
: Typical performance data of thermal IR radiators.

5.2 Examples on the Optimization of Spectrometer Systems
Graph 123A - grating curves in DUV
Graph 123A
shows three curves of an experimental setup with Deuterium Light Source,
Graph 123B - grating curves in upper orders 
Graph 123B
: a series of measurements documents the transfer of a spectrometer with Deuterium lamp (the emission curve is “D2“ – red), a UV silicon detector (efficiency curve is the brown “UV-Si”).

Change-over Wavelengths of Lamps, Gratings, and Detectors
 
Graph 124 - UV signal curves with 2 lamps
Graph 124
demonstrates the selection of the change-over point.
Graph 125 - well resolved Xenon spectrum
Graph 125 displays a measured Xenon spectrum in the range of 200 – 1700 nm.

5.2.1 and what will at the End really come out of an Illumination Monochromator System?


5.3 Light Transfer and Coupling by Fibre Guides and Optics

5.3.1 Fibreguides – Light Wave Guides – Fibre/fibre Optics
Graph 126 - principle of fibre optics
Graph 126
: The components of an optical fibre guide and it´s angles.
 Graph 127 - transfer efficiency of fibre guides
Graph 127
: Several typical Transmission Curves of Materials, used in optical Spectroscopy.

5.3.2 Fibre Optic Parameters
5.3.2.1 Absorption

5.3.2.2 Solarization
5.3.2.3 Bending Radius
5.3.2.4 Losses of in/out Coupling
5.3.2.5 Modes and Polarization
5.3.2.6 Acceptance Angle
5.3.2.7 Fluorescence, Raman, and Brillouin Effects in Fibres
5.3.3 The "flexible optical Bench", and a serious Precaution

5.3.4 Typical Kinds and Variations of single Fibres and Fibre Cables

 Graph 128 - variations of fibre cables
Graph 128
: Often found fibre optic cable designs:

5.4 Transfer Systems

5.4. Transfer Systems in General

Graph 125A - the general rule of light transfer

Graph 125A: the general Rule of Light Transfer

5.4.1 In and Out Coupling by Optical Fibres only

 
Graph 129 - fibre optic coupling
Graph 129 shows the coupling of a spectrometer with fibre optics, without further optics.  

5.4.2 In and Out Coupling by Lens Systems

Graph 130 - Versions of lens coupling
Graph 130
reviews some solutions to couple spectrometer and fibre optics by lens systems.

5.4.3 In and Out Coupling by Mirror Systems
 Graph 131 - some coupling solutions with mirrors

Graph 131
deals with the mirror coupling of spectrometer and fibre guide.

Hoping, the study of the book Elements of dispersive optical Spectrometers will be of help for you, we remain with special thanks for your interest.

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