Quantum Northwest qpod User manual

Instruction
Manual
qpod®
Temperature-Controlled Sample Compartment for
Fiber Optic Spectroscopy
22910 East Appleway Avenue, Suite 4, Liberty Lake, WA 99019-8606
Tel: [phone] • Fax: [phone] • E-mail: [email protected]om • Web: www.qnw.com 9/15/11

Table of Contents
qpod Temperature-Controlled Sample Compartment for Fiber Optic Spectroscopy 2
Overview 2
Items Included with Your Purchase 2
System Setup 3
Optics 3
System Operation 5
Error Conditions 6
Serial Control for the qpod 6
Temperature Specifications 6
Other Specifications 7
Optical slits provided with the qpod 8
Appendix: Serial Communications for Quantum Northwest Temperature Controllers 9
Temperature Performance Certificate 14
1

qpod Temperature-Controlled Sample
Compartment for Fiber Optic Spectroscopy
Manual Version 07-13-11
OVERVIEW
The qpod is a complete sample compartment for
fiber optic spectroscopy, including a Peltier-
controlled cuvette holder with magnetic stirring, and
fused silica lens systems with SMA fiber optic
connectors.
You have purchased one of three qpod packages.
The CUV-qpod-ABSKIT provides collimating optics
to pass light straight through for absorbance,
transmittance or turbidity measurements. The
CUV-qpod-FLKIT provides imaging lens systems
for excitation and detection of fluorescence
emission at right angles. The CUV-qpod-MPKIT is
a multipurpose kit with a combination of optics that
may be used for either absorbance or fluorescence
measurements.
The qpod is constructed of a single molded
housing. A Peltier-controlled cuvette holder in the
center provides temperature control and variable
speed magnetic stirring, and holds optical slits for
limiting light access to the cuvette as needed. A dry
gas purge may be used to minimize condensation
when working at low temperatures. SMA fiber optic
connections and high quality fused silica optics may
be inserted in different combinations into optical
ports in the walls surrounding the cuvette holder.
Accessories such as polarizers and filter holders
may be inserted in the light paths. Spherical
mirrors may be used to enhance excitation or
emitted light. All optics provide focusing and
position adjustments for maximizing signal
throughput.
ITEMS INCLUDED WITH YOUR
PURCHASE
A. qpod and Optics Package
1. qpod with lid and cap
2. one of three optical kits:
ABSKIT - optics for absorbance or
transmission measurements:
a. 2 QCL-UV collimating lenses
FLKIT - optics for fluorescence
measurements:
a. 2 QIL-UV imaging lenses
b. 2 QMP mirror plugs
MPKIT - multipurpose kit:
a. 2 QCL-UV collimating lenses
b. 2 QIL-UV imaging lenses
c. 2 QMP mirror plugs
3. plastic utility box containing:
a. 5/64-inch hex driver
b. set of optical slits
c. stir bar
d. 2 blanks for unused optical ports
B. Temperature Controller
1. TC 125 Temperature Controller
2. qpod manual
3. electrical cable to connect the TC125 to
the qpod
4. power cord for the Temperature Controller
5. If you ordered the SER 2.2 option, you will
also find:
a. CD with the program Serial Control
V2.2
b. USB cable to connect the
Temperature Controller to your
computer
C. BATH 100
1. submersible pump
2. plastic bucket
3. a length of tubing
D. Optional Items - Any optical components such
as polarizers or optical filter holders
2

SYSTEM SETUP
1. If desired, fasten the qpod down to a table or
optical breadboard. The holes in the corners of
the base are located and sized such that it will
attach via ¼-20 screws to a table with 1-inch
centers or with M-6 screws to a table with 25
mm centers.
2. Supply circulating water to the Peltier unit.
Attach tubing from the submersible pump to
either one of the water hose barbs on the qpod.
Attach another piece of tubing from the qpod
back to the bucket. Put water in the bucket,
turn on the pump by plugging it into an outlet
and check to be sure that water is flowing back
into the bucket. Check for leaks. Unplug the
pump until you have completed the remainder
of the system set up.
3. If you plan to work at low temperatures, connect
a source of dry gas (typically nitrogen) using a
length of tubing with 1/8” (3mm) inside
diameter, to the hose barb labeled “gas” on the
side of the qpod.A flow of gas must be used
to prevent condensation on the faces of the
cuvette when working below the dew point
temperature. Set the dry gas flow rate to 50 -
200 cc/min.
4. Attach the electrical cable between the TC 125
and the qpod.
5. Attach the power cord to the back of the
temperature controller and plug it in.
6. Insert optics as described in the next section.
OPTICS
There are two basic optical configurations for the
qpod: one to measure absorbance and the other
to measure fluorescence.
Optics to measure absorption
Figure 1 - Absorbance configuration
As shown in Figure 1, to set the qpod up for
absorbance measurements insert collimating lens
on any two opposite sides of the qpod. Put black
plastic blanks from the qpod accessory kit in the
other two optical ports. One lens collimates the
output from the source fiber into a beam about 5
mm in diameter. The beam passes through the
sample and is then focused on the collection fiber.
A collimating lens assembly contains a single 6 mm
diameter, 12 mm focal length, broadband AR-
coated, fused silica lens whose principal point is
located 12 mm from the end of the fiber.
Optics to measure fluorescence
Figure 2.
3

As shown in Figure 2, to set the qpod up for
fluorescence measurements insert an imaging lens
to focus light from a source fiber into the center of
the sample cuvette. Place another imaging lens at
90° to the source lens images the illuminated
volume onto a collection fiber. To enhance
collection efficiency, spherical mirrors may be place
on the remaining positions of the qpod. One
opposite the excitation fiber focuses the excitation
source back through the sample and another
opposite the collection lens focuses extra emitted
light back through the sample to roughly double the
amount of emitted light collected.
An imaging lens assembly contains two ½-inch
diameter, 30 mm focal length, broadband AR-
coated fused silica lenses. The principal point of
one lens is located 30 mm from the fiber and the
principal point of the second lens is located 30 mm
from the center of the cuvette. Thus the imaging
lens pair creates an image of the fiber end, without
magnification, in the center of the cuvette, or
images the illuminated volume on a collection fiber.
Inserting a lens into the qpod
Figure 3 - Components of a lens assembly
1. Use the 5/64-inch hex screwdriver from the
qpod accessory kit to loosen the set screw
(Figure 3).
2. Remove the silver sleeve with a black end
piece from the lens assembly. Set it aside.
3. Screw the empty optical assembly all the way
into the appropriate position in the qpod.If you
are using an accessory component such as a
filter holder or polarizer. First place the
accessory in the qpod. As you screw in the
empty lens assembly the accessory will fit over
its end and then snap into place.
4. Look for the location of the set screw. If it is in
a difficult position to reach, remove the three
fiber steering screws, rotate the end of the
optical assembly until the set screw is
accessible, and reattach the alignment
assembly so the screw is more available. The
steering screws compress an o-ring, permitting
fine alignment of the end of the fiber relative to
the lens.
Figure 4 - Attaching the fiber optic to the SMA
connector
5. Now, unscrew the silver sleeve from the black
end piece revealing the SMA connector
(Figure 4).
6. Slide the silver sleeve over the end of the fiber
optic connector and cable, leaving the threaded
end toward the end of the cable.
7. Attach the fiber optic cable to the SMA
connector.
4

8. Holding the black end piece, screw the silver
sleeve back into place.
9. Insert the SMA connector and silver sleeve into
the hole in the optical assembly. For a first
adjustment, insert the assembly until the
alignment groove is even with the face of the
lens assembly. Later, you can optimize the
signal intensity by sliding the SMA connector
and silver sleeve in deeper.
SYSTEM OPERATION
1. Use a liquid sample of at least 1.5 ml and place
it in a standard 1 x 1-cm square cuvette. Place
the cuvette in the cuvette holder in the center of
the qpod. Standard microcuvettes may also be
used for smaller volumes. The qpod is
designed to hold microcuvettes in which the “z”
dimension (distance between the bottom of the
cuvette and the optical center line) is 8.5 mm.
Note: The qpod is intended to hold a cuvette with a
standard wall thickness of 1.25 mm and total width
of 12.5 mm. Cuvettes with unusually thick walls will
not properly fit and may damage the holder.
2. If needed, place the magnetic stir bar in the
cuvette and turn the magnetic stirrer knob
located on the front of the temperature control
until the desired speed is reached.
3. To monitor the temperature inside the cuvette,
plug a standard Series 400 or Series 500
thermistor probe into the ¼ - inch phone plug
jack located in the back of the temperature
controller. Standard Series 400 and 500
thermistor probes are available from a number
of suppliers. We favor the model ON-402-PP
by Omega (omega.com). Thread the probe
through the split rubber plug in the qpod cap
and place it in the cuvette out of the way of the
light.
4. Provide a source of light and a detector. You
may maximize the signal by adjustments of the
three fiber steering screws, making small
movements of the position of the fiber end
relative to the lens, and by loosening the set
screw to insert the silver sleeve deeper into the
lens assembly. Inserting the silver sleeve
further into lens assembly moves the end of the
fiber closer to the lens, altering the focus of the
light. This adjustment is most important at UV
wavelengths.
5. Use the optical slits or blanks (provided in the
qpod accessory kit) around the cuvette in a
manner that correctly limits the excitation and
emission light.
6. Put the cover and cap on the qpod.
7. Turn on the submersible pump by plugging it in.
Cooling water flows through a heat exchanger
and removes heat from the thermoelectric
device when the temperature of the holder is
being lowered. Insufficient flow will allow the
heat exchanger temperature to rise. If the
temperature of the heat exchanger exceeds a
certain cutoff value, temperature control will be
automatically shut down to protect the holder.
Cooler circulating water can result in improved
performance of the cuvette holder at low
temperatures, whereas warmer water can
improve performance at very high
temperatures. Do not use warm or room
temperature water when setting
temperatures near room temperature, as
temperature instabilities are likely to arise.
Cool the circulating water by the addition of ice
to the bucket.
A circulating bath may be used to provide
circulating fluid to the qpod. Using such a bath,
temperatures well below the specified -30 °C
lowest temperature may be readily achieved.
Contact us for suggestions on how to achieve
very low temperatures.
8. Turn on the temperature controller using the
switch located on the left side of the rear panel
of the temperature control unit. When the TC
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125 is turned on, the display briefly indicates
the software version number running in the
microcontroller and an ID number that identifies
the kind of sample holder that is being
controlled (see further information in Appendix
1).
9. Set the target temperature using the up and
down arrows. The normal temperature range is
-30 °C to +105 °C. Contact us for suggestions
if you would like to work at temperatures lower
than -30 °C.
If there is no external probe plugged into the
rear of the unit, the TC 125 displays the holder
temperature, the precise temperature measured
in the metal body of the cuvette holder, and the
target temperature, the temperature that the
controller is attempting to achieve. The holder
temperature sensor is located at cuvette
window height on one of the corners of the
cuvette tower. If a probe is being used, then
the controller displays instead the holder
temperature and the probe temperature. To
see the target temperature, briefly touch either
the up or down arrow button.
10. To begin controlling the temperature, depress
the run/stop button located to the left of the
display. Depressing the run/stop button a
second time will turn temperature control off.
When the sample holder approaches the target
temperature, the red light located on the upper
left corner of the front panel of the temperature
controller, will flash slowly. When the sample
holder reaches and holds within ± 0.02 °C of
the target temperature, the red light will remain
constant.
11. If you purchased the Serial Control option, you
may load the software at any time and begin
using it. Instructions are found in the Help
system.
12. After measurements are completed, depress
the run/stop button to stop temperature control,
and turn off power and water sources.
ERROR CONDITIONS
Rapid flashing of the red light indicates an error
condition. The common errors that will display are:
Error conditions E5, E6 and E7 – Check Cables.
One or more of these error conditions is likely to
arise if the electrical connection between the
Temperature Controller and the qpod is not secure.
In this case, turn off the power to the unit, check the
cable, turn on the power, and resume work.
Error condition E8 – Low water flow. This error
condition indicates that the heat exchanger on the
thermoelectric cooler is getting too warm. This
heating will occur if insufficient cooling water is
flowing into the device. Error condition E8 will
automatically shut down temperature control to
prevent damage to the unit. If this occurs, improve
cooling water flow and re-start temperature control.
If correcting these problems does not solve the
error messaging, or if other errors are displayed,
contact Quantum Northwest by calling (509) 624-
9290 or by e-mailing us at [e-mail].
TEMPERATURE SPECIFICATIONS
Temperature capabilities of Quantum Northwest
cuvette holders depend on the product you have
and the conditions under which it is operated.
Maximum Temperature.The qpod system is
limited to temperatures below 105 °C. A higher
target temperature cannot be set since such
temperatures may damage internal components.
This maximum can be attained with coolant at 15
°C or above.
Minimum Temperature. While the qpod system is
capable of operation as low as -40 °C, the minimum
useful temperature depends on the conditions
under which it is used.
1. Without special conditions, using room
temperature coolant, the minimum is the dew
point temperature of the air at the location of use
(roughly 5 °C). Below the dew point
6

temperature, condensation on the cuvette
windows will interfere with measurements.
2. With a dry gas flow rate of at about 200 cc/min
into the gas inlet of the sample holder, the
minimum temperature is about -10 °C. Below
-10 °C there is a risk of frosting of the cuvette
surfaces.
3. When using ice water as coolant and dry gas
flow, the minimum temperature is about -25 °C.
In high humidity environments there is
increased potential for frost formation even with
gas flow.
Probe Temperature Range. The TC 125, TC 225
and TC 425 temperature controllers accept
standard 400 and 500 Series thermistor probes.
These probes may be obtained from supply
companies such as Cole Parmer (coleparmer.com).
Standard 400 Series temperature probes will
measure the temperature within ±0.2 °C over the
range of 0.0 to 70.0 °C. The probe will operate over
the full range of -40 °C to +105 °C, but an individual
probe will need to be calibrated by the user outside
of the 0.0 to 70.0 °C range. The 500 Series probes
are less standardized and may require calibration
by the user. 500 Series probes may be convenient,
because they are available in very small diameters.
Other Specifications
Variable speed magnetic stirring is provided
primarily to speed up temperature equilibration.
Two stir bars are included.
A dry gas purge is provided. The gas travels
through the base of the cuvette holder for
temperature equilibration and then blows onto the
exposed faces of the cuvettes. The gas purge
minimizes condensation on the cuvette surfaces.
An opaque lid covers the tops of the cuvettes to
provide isolation from the ambient environment.
An optional serial interface is available for remote
computer control (see Appendices).
Optical access. The qpod holds a standard 1 cm
square cuvette and precisely maintains its
temperature. Access is provided on four sides of
the cuvette through optical ports 10 mm wide by 12
mm high.
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8

Appendix- Serial Communications for Quantum Northwest
Temperature Controllers
This document provides the serial communications protocols for version 9.1 of the firmware on temperature
controllers TC 125, TC 225 and TC 425.
The version number and the ID (see below) are shown briefly on the display when the temperature controller is
turned on.
With the exception of setting the rate of stirring, all functions of the temperature controller can be managed from
a computer, using the command set described below. If you purchased your unit as a component of a
spectrometer from certain manufacturers, this feature may be implemented through traditional RS232 serial
connectors on the computer and the controller. In this case they will be connected by a standard 15-pin serial
extension cable (male connector on one end and female on the other). No driver installation should be needed.
Otherwise the serial linkage will be established through a USB connection between the computer and the
controller. In this case the controller includes electronics which convert the USB connection to a serial
communications port. However, for the port to be available to programs on the computer it will be necessary to
load driver software. It is important that the driver software be loaded before connecting a USB cable between
the controller and the computer. Contact Quantum Northwest for further information.
Quantum Northwest can provide a control program written specifically for control of all functions of the
temperature controllers. Ask for program T-App.
To communicate with the controller, one must adhere to the conventional notation: 8/N/1.
Baud: 19200
Data Bits: 8
Parity: None
Stop Bit: 1
Flow Control: None
For many of the commands listed below the controller returns information in response to the command. All
commands and responses are delineated by left and right square brackets ( [ ] ). In this document an ellipsis
(……) is used to distinguish responses from commands. Any text sent to the controller not enclosed within
brackets will be ignored.
[command] purpose of the command (sent to the controller)
......[reply] meaning of the reply (received from the controller)
1. Identify
[F1 ID ?] What is the ID number of the sample holder being controlled?
......[F1 ID 31] Sample holder is a four-position turret with probe capability.
Assigned Identities:
ID = 10 - single cuvette holder
11 - single cuvette holder with probe capability
12 - high temperature single cuvette holder
20 - dual cuvette holder
21 - dual cuvette holder with probe capability
22 - dual-controlled titrator
30 - 4-position turret
31 - 4-position turret with probe capability
32 - 6-position turret (or linear cell) changer
Identity Classes:
9