1. Components of Optical Instruments
Chapter 7
Components of Optical Instruments

2. Components of Optical Instruments
Typical spectroscopic instruments contain five components: (1) a stable source of radiant energy, (2) a transparent container for holding the sample, (3) a device that isolates a restricted region of the spectrum for measurement, (4) a radiation detector that converts radiant energy into a signal detector, (5) a signal processor and readout.

3. Components of Optical Instruments
Absorption
Fluorescence
Phosphorescence
Scattering
Emission
Chemiluminescence

4. Rayleigh & Raman Scattering
Occur when the dimensions of the particles that cause the scattering are small in comparison to the wavelength of the incident radiation. Dissolved particles can result in Rayleigh and Raman scattering.
A type of Raman Spectrometer: FRA 106/S Spectrometer

5. Sources of Radiation Requirements Sufficient power
Stability over long periods of time
Voltage regulation required as radiant power varies exponentially with voltage

6. Lasers

7. Lasers Pumping Spontaneous emission (fluorescence) Stimulated emission
Absorption

8. Wavelength Selectors Filters Interference Filters Interference Wedges
Absorption Filters

9. Wavelength Selectors
Monochromators- one color - pass a narrow band of wavelengths
The SURE_SPECTRUM is an imaging spectrograph and scanning monochromator that features dual exit ports for maximum flexibility.

10. Wavelength Selectors
View of inside of monochromator

11. Wavelength Selectors

12. Radiation Transducers
Photomultiplier

13. Radiation Transducers
Photodiode Arrays (PDA)

14. Radiation Transducers
Charge Transfer Devices
Charge Injection Devices (CID)
Charge-Coupled Devices (CCD)

15. Signal Processors & Readouts
Photon Counting
Advantages:
Improved signal-to-noise ratio
Sensitivity to low radiation levels
Improved precision for a given measurement time
Lowered sensitivity to photomultiplier tube voltage and temperature fluctuations
Detection method of choice in fluorescence, chemiluminescence, and Raman spectrometry

16. Signal Processors & Readouts
Photon Counting
Disadvantages:
Required equipment is more complex and expensive
Technique has not been widely applied for routine molecular absorption measurements in ultraviolet and visible regions

17. Principles of Fourier Transform Optical Measurements
Transforms data set from time domain to frequency domain
Advantages
Throughput
High resolving power
Interferometers
Michelson
Mach-Zender
Fabry-Perot

18. References www.anachem.umu.se/jumpstation.htm