Download Activity: Emission spectroscopy and smart sensors

Activity: Emission
spectroscopy and
smart sensors
What is a Smart Sensor?

We will use the term “Smart Sensor” to refer
to systems that employs a sensor device
mated to microelectronics. In this activity we
will use a light emitter and a spectrometer for
our sensor system and a computer will take
the place of the microelectronics. The
system used in this activity is not engineered
to minimize size and power consumption but
clearly those would be goals in any widely
deployed commercial device.
Preparation for Activity


Items Needed: Ocean Optics Red Tide USB
650 Spectrometer, optical fiber lead for
spectrometer, Computer with Ocean Optics
Spectra Suite. Laser pointer light sources
red, green; other light sources.
An understanding of various emission light
sources
Instructor
To initiate the activity discuss the emission of light from a laser pointer-lead
students into a discussion of some of the principles of solid state lasers. Be
prepared to discuss some of the major ideas behind solid state lasers and
simulated emission. Read sections on quantum effects and the laboratory
on emission spectroscopy
Safety Consideration
WARNING: The output of the solid
state lasers in laser pointers and other
devices is potentially dangerous and
one needs to insure that the light is not
directed into the eyes of students,
graduate assistants or faculty members
A Red Tide USB650 spectrometer system
A “Red Tide” CCD detector based spectrometer, A CCD is an acronym for a
charge coupled device: Here a linear array of silicon sensors that
responds to light. In the spectrometer light is broken down into component
wavelengths by an interferometer and the output at each wavelength
sensed by the CCD sensor. The spectrometer covers the wavelength
range 350 nm to 1000 nm.
Optical fiber
End on view of the optical fiber showing glass interior. Optical fibers
for the Rid Tide 650 can be obtained for a variety of wavelength
ranges.
A Red Tide USB650 spectrometer system
with USB link and optical fiber attached
A “Red Tide” spectrometer connected to an optical fiber(red/blue) and a USB computer interface
(clay ). The USB link is used to bring power the spectrometer and transmit data to the computer.
Light is brought to the spectrometer using the optical fiber.
Experimental
Direct the output of the laser to the
open end of the optical fiber. It is
useful to have the fiber and light
source well secured so that
experiments testing smart sensor
designs can be easily carried out.
Questions



What observations can you make concerning
the nature of the red and green laser
spectra?
What problems do you see in the design of
this activity? What improvements would you
make?
What other kinds of measurements can you
see being carried out with this system both
indoors and out.
Design


Based on your observations during this
activity design smart sensor systems for two
different tasks.
What would be necessary to build a smart
sensor system ( somewhat like the system
discussed in this activity) capable of detecting
a specific airborne chemical.
Red Laser pointer
Red Laser Pointer
Relative Intensity
4500
4000
3500
3000
2500
2000
Series1
1500
1000
500
0
350
550
750
nm
950
Green laser pointer
Green LED
400
Relative Intensity
350
300
250
200
Series1
150
100
50
0
350
550
750
nm
950