Ocean Optics CHEM2000 User Manual

Page 25

3: Experiment Tutorial

The software calculates

(or

) by the following equation:

- D

x 100%

Where:

S = Sample intensity at wavelength

D = Dark intensity at wavelength

R = Reference intensity at wavelength

Common applications include measurement of transmission of light through solutions, optical filters,
optical coatings, and other optical elements such as lenses and fibers.

Note

For transmission of light through solutions, we offer a transmission dip probe with screw-
on, removable tips in 2-mm, 5-mm or 10-mm path lengths. Contact Ocean Optics for
more information.

►

Procedure

To take a transmission measurement:

1. Select

Scope under Mode of Operation in the software display area. Make sure the signal is on

scale. Adjust acquisition parameters so that the peak intensity of the reference signal is about
3500 counts. Take a reference spectrum by first making sure nothing is blocking the light path
going to your spectrometer. The analyte you want to measure must be absent while taking a
reference spectrum. Take the reference reading by clicking the Reference button in the software
display area. (This command merely stores a reference spectrum. To save a spectrum, you must
select File | Save Spectral Values from the menu.) Storing a reference spectrum is requisite
before the software can calculate transmission spectra.

2. While still in Scope Mode, take a dark spectrum by first completely blocking the light path going

to your spectrometer. (If possible, do not turn off the light source. If you must turn off your light
source to store a dark spectrum, make sure to allow enough time for the lamp to warm up before
continuing your experiment.) Take the dark reading by clicking the Dark button in the software
display area. (This command merely stores a dark spectrum. To save a spectrum, you must select
File | Save Spectral Values from the menu.) Storing a dark spectrum is requisite before the
software can calculate transmission spectra.

3. Begin a transmission measurement by first making sure the sample is in place and nothing is

blocking the light going to your sample. Then select Transmission under Mode of Operation in
the software display area. Click on the Scan button in the display area to take a scan. If Single is
selected, only one scan will be taken. If Continuous is selected, the spectrometer will
continuously take scans until you click on the Stop button. To save the spectrum, select File |
Save Spectral Values from the menu.

105-00000-CHM-02-0405

PRELIMINARY DRAFT