simple presentation to understand different between radiometer, spectrometer, spectroradiometer.

1. INDIAN INSTITUTE OF TECHNOLOGY
BHUBANESWAR
Introduction to Spectroradiometer
by :- Girish PATIDAR
SEOCS
17CL06003

2. Content
• Introduction to Spectroradiometer
• Components of Spectroradiometer
• Comparison with other instruments
• Introduction of sensors

3. Spectroradiometer
Spectroradiometer are devices designed to measure the Spectral
power distribution of a source.
Spectral power distribution: - Spectral power distribution of a source
describes how much flux reaches the sensor over a particular wave
length and area.
This can be also refer to the concentration as a function of wavelength
of any radiometric or photometric quantity.

4. Components of a spectroradiometric system
• Input optics that gather the electromagnetic radiation from the
source.
• A monochromator, separating light into its component wavelengths
• A detector
• A control and logging system to define data and store it.

5. Input optics
• The front-end optics of a Spectroradiometer includes the lenses,
diffusers, and filters that modify the light as it first enters the
system. The material used for these elements determines what
type of light is capable of being measured.
• Example- To take UV measurements, quartz is used rather than
glass lenses.

6. Monochromator
A monochromator is used to sample or separate different wavelengths
from the source and essentially produce a monochromatic signals of
different wavelengths
Detectors
This device is used to measure intensity of different wavelength using
different techniques based on application.
photoemissive detectors, semiconductor devices, or thermal detectors.

7. Comparison with other instruments
• Spectroradiometer:- A radiometer that measures the intensity of
radiation in multiple wavelength bands (i.e., multispectral).
• Spectrometer:- A device that is designed to detect, measure, and
analyze the spectral content of incident electromagnetic radiation.
Conventional imaging spectrometers use gratings or prisms to
disperse the radiation for spectral discrimination.
• Radiometer:- An instrument that quantitatively measures the
intensity of electromagnetic radiation in some bands within the
spectrum. Usually, a radiometer is further identified by the portion of
the spectrum it covers. example, visible, infrared, or microwave.

8. Different sensors
• Spectroradiometer:- MODIS etc
• Spectrometer:- AVHIS, AHS, AIS etc
• Radiometer:- VHRR, AVHRR etc

9. MODIS
The moderate-resolution imaging Spectroradiometer is a payload of aqua
and terra satellite
The instruments capture data in 36 spectral bands ranging in wavelength
from 0.4 µm to 14.4 µm and at varying spatial resolutions
2 bands at 250 m, 5 bands at 500 m and 29 bands at 1 km.
With its low spatial resolution but high temporal resolution, MODIS data
is useful to track changes in the landscape over time. Examples of such
applications are the monitoring of vegetation health by means of time-
series analyses with vegetation indices etc.

10. THANK YOU