component of optical instrument
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Transcript of component of optical instrument
Component of Optical Instrument
monochromatorsample cell
detector
light source
slit
diff
ract
ion
grat
ing
optical system
Component of Optical Instrument
Component of Optical Instrument
Basic components
provides the light to be passed through the sample.
1. Light Sources
a source must generate a beam of radiation that is sufficiently powerful for easy detection and measurement.
- Hydrogen discharge: ultraviolet Light.
- Hollow Cathode Lamps (HCL) - tungsten Lamp: visible light .
its output power should be stable for reasonable periods.
Basic components
Used to select a given wavelength of the light from the light source
2. Wavelength selection (Monochromator)
Mono = single Choroma = colorThere exists many techniques• Prisms• Filter• Diffraction gratings • Stray light• Wavelength range• Double monochromator`
Basic components
Used to select a given wavelength of the light from the light source
2. Wavelength selection (Monochromator)
Mono = single Choroma = colorThere exists many techniques• Prisms• Filter• Diffraction gratings • Stray light• Wavelength range• Double monochromator`
Polychromatic Radiation
Narrow Band of Radiation
Glass Plate
Metallic Film
Dielectric Material
Basic components1. MonochromatorDiffraction gratings
To obtain a specific wavelength
1. entrance slit.2. concave mirror or lens.3. a prism or grating.4. focal plane.5. exit slit.
Exit SlitEntrance Slit
Grating
FocalPlane
Basic components
A container that contains a sample is usually called "cell“
has fixed length & volume. usually round or square cuvette. made of material that does not absorb light in the wavelength range.Two types are available:- - Glass – visible region. - Quartz – ultraviolet.
3. Sample cell
Basic components
to convert the radiant energy to a measurable signal; and to a readout device
“Detector” is a device that indicates the existence of some physical phenomenon.
The term transducer is used to indicate the device that converts quantities, such as light intensity, into such electrical signals that can be subsequently amplified, manipulated, and finally converted into numbers.
4. Transducer and Detector
Basic components
Ideal detector : high sensitivity. high signal/noise. fast response time. constant response for λs. responds to low levels of energy.
4. Transducer and Detector
General design
An Absorption Instrumental Setup
An Emission or fluorescence or Scattering Instrumental Setup
An Emission Instrumental SetupWith thermal energy as source
ANY QUESTIONS ?
