Measuring diffuse reﬂectance of solid
samples with the Agilent Cary 60 UV-Vis

Application note
Materials

Authors
Dean Logan and Dr. Ursula Tems
Agilent Technologies
Mulgrave, Victoria, Australia

Abstract
Measurements of solid materials are often difﬁcult due to the size, shapeand location of the samples. Large samples have to be broken for pieces toﬁt into an instrument sample compartment. However, many samples muststay intact and cannot be destroyed, such as when collecting reﬂectanceand color data on a car at the end of the painting process. The ability tomeasure external to the instrument is preferable. Using the Agilent Cary
60 UV-Vis spectrophotometer and the remote ﬁber optic diffuse reﬂectanceaccessory addresses this need.
The Cary 60 has a reputation for outstanding performance when measuringliquid samples remotely via ﬁber optic probe accessories. Now the Cary
60 extends this performance to include fast and accurate solid sample
reﬂectance measurements. The Agilent Cary 60 Remote Diffuse ReﬂectanceAccessory (DRA) (Figure 1) beneﬁts from the same unique Cary 60
technology, proven for testing liquids.

Method
Data was collected using the Cary 60 Remote DRA andthe Cary WinUV Scan application. All color traces werebaseline corrected and run over the range 360–830 nm.
The 100% reﬂectance baseline was collected using awhite PTFE sample.

Light switch
Read switch
VideoBarrelino

Results
TargetFiber optic

The spectra obtained from the four PTFE color samples
are displayed in the graph below (Figure 2). The traces
show typical proﬁles for PTFE color samples and allcolor spectra show very low noise.
100Figure 1. Cary 60 Remote DRA

White PTFEThe Cary 60’s highly focused beam makes it ideal forﬁber optic work, offering excellent coupling efﬁciency
and high light throughput, which equates to better
photometric performance. In addition, its room-light
immunity enables sample measurements to be taken
outside the sample compartment.

80Yellow
PTFE

RedPTFE

Blue
PTFE

Green
PTFE%R

60
40
20

The Cary 60 Remote DRA design is optimized to use
optical ﬁber up to 1.5 meters in length. The ﬁberchannels light out of the instrument and focuses a1.5 mm light patch onto the sample. The accessory
has a 0/30° beam geometry, which allows diffusereﬂectance to be measured by a detector mounted
within the accessory. To assist accurate placement ofthe accessory on the sample, the Cary 60 Remote DRA
includes a video camera that provides visual feedbackon the computer screen. The display shows the exact
point at which reﬂectance data will be collected.

0400

500600700
Wavelength (nm)Figure 2. Diffuse reﬂectance spectra of four PTFE color samples

800

Reproducibility scans (Figure 3) were collected byrunning 10 repeated scans on one of the PTFE samples.
The blue PTFE sample was selected because its spectra
contain more structure than the other colors.
10080Experimental%R6040Materials•

Cary 60 UV-Vis spectrophotometer•

Cary 60 Remote DRA•

Cary 60 ﬁber optic coupler•

Cary WinUV software•

PTFE color samples

200400

500

600
700
800
Wavelength (nm)Figure 3. Diffuse reﬂectance spectra of 10 repeated scans of a blue PTFE
sampleZooming in on the structure between 460 nm and500 nm (Figure 4), shows very reproducible traces. The
average standard deviation between the 10 traces was0.053 (%R). The highest was 0.213 (%R) and the lowest
0.007 (%R).
2Conclusion62

The Cary 60 with Remote DRA is ideal for use when thesample must not be damaged, or where samples cannot
be placed in the instrument sample compartment.

%R60Examples include:

5856
470

480490
Wavelength (nm)Figure 4. Diffuse reﬂectance spectra of 10 repeated scans of a blue PTFE
sample from 460 nm to 500 nm

Video output
To ensure accurate placement of the Cary 60 Remote
DRA onto the PTFE color samples, the integrated video
camera was used. Any contaminants on or in thesample (Figure 5) could be easily seen on the computer
monitor and avoided. Data was collected on the PTFE
color samples, where the video ﬁeld showed thesamples were clean (Figure 6).

a. Hairb. Plastic thread

Figure 5. Screen captures of the video output from the Cary 60 Remote DRA.
White PTFE with contaminant (a) hair, (b) plastic thread

White PTFE

Blue PTFE

Yellow PTFE•Art restoration and conservation1,2•

Q/C in printing, paint and automotive industries

The integrated video camera allows for accurate
placement on the sample for analysis.
The Cary 60 with Remote DRA presents a new solution
for remote reﬂection measurements of solid samples,
beneﬁting from the unique optical design of the Cary
60 that allows for superior light throughput, andphotometric performance.

References
1. Marco Leona, Francesca Casadio, Mauro Bacci,& Marcello Picollo, “Identiﬁcation Of The PreColumbian Pigment Maya Blue On Works Of Art
By Noninvasive Uv-Vis And Raman SpectroscopicTechniques,” JAIC 2004, Volume 43, Number 1,Article 4 (pp. 39 to 54)
2. Dan Drollette, “Spectrophotometer Finds Cure for
Edo Blues,”
http://www.photonics.com/Article.aspx?AID=5620

Green PTFERed PTFE

Figure 6. Screen captures of the video output from the Cary 60 Remote DRA3

www.agilent.com/chem
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damages in connection with the furnishing, performance or use of this material.
Information, descriptions, and speciﬁcations in this publication are subject to change
without notice.
© Agilent Technologies, Inc. 2012
Published December 3, 2012
Publication number: 5991-1430EN