Quantum qpod 2e Instruction Manual

22910 East Appleway Avenue, Suite 4, Liberty Lake, WA 99019-8606

Tel: [phone] • Fax: [phone] • E-mail: [e-mail] • Web: www.qnw.com

Instruction

Manual

qpod 2e

™

Temperature-Controlled Sample Compartment for Fiber

Optic Spectroscopy

1

Table of Contents

qpod 2e Temperature-Controlled Sample Compartment for Fiber Optic Spectroscopy 2

Overview 2

Items Included with Your Purchase 2

System Setup 3

Software Installation 4

Optics 4

System Operation 6

Error Conditions 7

Temperature Specifications 7

Other Specifications 7

Optical slits provided with the qpod 8

Appendix 1: Computer Control 9

Appendix 2: Q-Blue Program Commands 13

Appendix 3: Example Script: Temperature Ramping 18

2

qpod 2e Temperature-Controlled Sample Compartment

for Fiber Optic Spectroscopy

Manual Version 06-04-15

OVERVIEW

The qpod 2e is a complete sample compartment
for fiber optic spectroscopy, including a Peltier­controlled cuvette holder with magnetic stirring,
and fused silica lens systems with SMA fiber optic
connectors. The qpod 2e housing contains a PID
temperature controller that is operated via USB
using the computer program Q-Blue.

The qpod 2e is available in three different
packages. The CUV-qpod 2e-ABSKIT provides
collimating optics to pass light straight through for
absorbance, transmittance or turbidity
measurements. The CUV-qpod 2e-FLKIT provides
imaging lens systems for excitation and detection
of fluorescence emission at right angles. The CUV-
qpod 2e-MPKIT is a multipurpose kit with a
combination of optics that may be used for either
absorbance or fluorescence measurements.

The qpod 2e 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 2e and Optics Package

1. qpod 2e 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. qpod 2e accessory kit containing:

a. 5/64-inch hex driver
b. set of optical slits
c. stir bar
d. 2 blanks for unused optical ports

4. AC adapter

5. USB cable

3

6. Q-Blue CD with temperature control software,

help file and this qpod 2e manual.

C. BATH 100

1. submersible pump

2. plastic bucket

3. a length of tubing

D. Optional Items - If you ordered any optical

components separately, such as polarizers or
optical filter holders, you will find them packed in a
separate internal box.

SYSTEM SETUP

1. If desired, fasten the qpod 2e 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
2e. Attach another piece of tubing from the
qpod 2e 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 2e. 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.

SOFTWARE INSTALLATION

The qpod 2e may be controlled using a USB cable.
If you will be using USB to control the qpod 2e you
must install the software before connecting the
hardware to the computer, otherwise the
sequence is not important.

4. Insert the Q-Blue software CD into the drive. If

the installation does not start automatically,
locate the Setup.exe file in the root directory
and run it. The installation process starts with
a small black window that is shown during
installation of the drivers needed to control the
qpod 2e through a USB connection. This
window will then be replaced by the software
installation window. Follow the onscreen
prompts to complete the installation.

Setting up for temperature control using USB

5. Connect the qpod 2e to your computer using

the USB cable provided. The New Hardware
installation process will begin automatically
and take a few moments to finish.

OPTICS

There are two basic optical configurations for the
qpod 2e: 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 2e up for
absorbance measurements insert collimating lens

4

on any two opposite sides of the qpod 2e. Put
black plastic blanks from the qpod 2e 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 AR­coated, fused silica lens whose principal point is
located 12 mm from the end of the fiber.

Optics to measure fluorescence

Figure 2 - Fluorescence configuration

As shown in Figure 2, to set the qpod 2e 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 2e. 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 AR­coated 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 2e

Figure 3 - Components of a lens assembly

1. Use the 5/64-inch hex screwdriver from the

qpod 2e 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 2e. If
you are using an accessory component such as
a filter holder or polarizer. First place the
accessory in the qpod 2e. 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, you may wish to
remove the three fiber steering screws, rotate
the end of the optical assembly until the set
screw is accessible, and reattach the alignment

5

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.

5. Now, unscrew the silver sleeve from the black

end piece revealing the SMA connector (Figure

4).

Figure 4 - Attaching the fiber optic to the SMA
connector

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.

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. The alignment
grove assumes visible light. For measurements
in the UV, the silver sleeve should be inserted
further. The calculated position of the
alignment groove also assumes that the qpod
will contain a standard 10 x 10 mm cuvette
filled with water. Other cuvettes and sample

may require minor adjustments to maximize
throughput.

6

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 2e. Standard microcuvettes may
also be used for smaller volumes. The qpod 2e
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 2e 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. Place the magnetic stir bar in the cuvette.

Stirring speed will be set by the program Q­Blue.

3. If you wish to monitor the temperature inside

the cuvette, plug a standard Series 400 or
Series 500 thermistor probe into the ¼ - inch
phone jack located on the corner of the qpod
2e to the left of the front panel. Thread the
probe through the split rubber plug in the qpod
2e cap and place it in the cuvette out of the
way of the light.

4. Provide a source of light and a detector.

5. Use the 5/64-inch hex driver from the

accessory kit to maximize the signal by
adjustments of the three fiber steering screws
(Figure 3). This adjustment will make small
movements of the position of the fiber end
relative to the lens. Also, loosen 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. (Measurements can be made

without these alignments. However, in the
unaligned system the reference spectrum may
change with temperature and must be re­measured each time the set temperature is
changed. Careful alignment will minimize such
artifacts.)

6. Use the optical slits or blanks (provided in the

qpod 2e accessory kit) around the cuvette in a
manner that correctly limits the excitation and
emission light.

7. Put the cover and cap on the qpod 2e.

8. 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 refrigerated circulating bath may be used to
provide circulating fluid to the qpod 2e. 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.

9. Plug power from the AC adapter into the qpod

2e front panel.

10. Connect the qpod 2e to your computer using

the USB cable.