Pyrex cells are the least expensive reference cells and the Pyrex material has good optical transmission, approximately 92%, between the wavelengths 350 and 2400 nm. The Pyrex reference cell can be used in an undergraduate or graduate level laboratory environment. Pyrex material is a rugged material resistant to chipping and cracking. The cells are made with flat windows of optical quality Pyrex to give good light transmission.
The Pyrex cells are tested for optical throughput before shipping . A laser diode source and power meter is used to test the cell throughput. The output power of the laser source is measured using the power meter to establish a base line. The power is measured again with the cell in the optical path. An acceptable power level percentage through the cell is above 84%.
The fill material is also tested. A tunable laser diode is used to scan over one of the absorption peaks. The laser system is adjusted to scan over one of the absorption wavelengths for the fill material. The wavelengths for the different fill materials are; Rubidium 780 nm, Cesium 852 nm, Sodium 589 nm and Potassium 764 nm. The atomic elements have various absorption lines at different wavelengths. Our cell testing is performed at lines that are well defined and are accessible using a laser diode source. The cell absorption lines are measured using linear absorption measurement. Our Pyrex reference cells are excellent filters for this type of experiment.
Specifications
Material
Pyrex
Cell Diameter
25 mm
Cell Length
75 mm
Pressure @ 25 °C
>1x10-7 Torr
Fill Stem
<10 mm
Window Angle
0°
Window Type
Flat
Window Thickness
3 mm
Minimum Transmission
>84%
Gas
Wavelength
Potassium K
764 nm
Sodium Na
589 nm
Cesium Cs
852 nm
Rubidium Rb
780 nm
A typical lab experiment using a Pyrex reference cell is a saturated absorption experiment on the Cesium 852nm absorption line. The experiment is used to examine the Doppler free absorption line of Cesium.
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Posted Comments:
Poster: klee
Posted Date: 2009-07-16 09:44:18.0
A response from Ken at Thorlabs to mverhaegen: If the unit does not work for your application, you can return it for credit, but you may be charged a restocking fee depending on the condition of the unit.
Poster: mverhaegen
Posted Date: 2009-07-15 11:38:04.0
Hello,
I am interested in three of your gas cells but I am not sure they will fulfill my requirements. Is is possible to test one of the following unit : CP25075-K, CP25075-NA or CQ19100-I. In the case the unit does not work for my application, is it possible to have a refund or a credit for my future Thorlabs purchases?
Best Regards,
Marc Verhaegen
The Quartz Reference Cells are designed for very precise measurement of an absorption peak. The cell windows and body are made from Quartz material. The windows are designed with a 2 degrees wedge to eliminate the etalon effects of parallel surfaced windows. The wedged windows are also angled to compensate beam offset due to the index of the quartz material. The quartz fill materials include Rubidium, Cesium, and Iodine. In addition, Rubidium Isotope 87 and 85 are also fill materials. Natural Rubidium contains both isotopes 85 (72.15%) and 87 (27.85%). The Rubidium isotopes 85 and 87 have a purity level greater than 98%.
Although both Pyrex and quartz cells can contain a buffer gas, the quartz cells are typically used in these applications. An addition of a buffer gas will tend to shift the absorption wavelength and broaden the peak. Neon, Helium and Nitrogen are typical gases used for the buffer. If a buffer gas is needed in a reference cell, the pressure of the gas needs to be specified.
The quartz cells are tested for optical throughput and fill material purity. Test setup:
A typical application of the quartz reference cells is as a filter for stabilizing the frequency of a laser diode. The diagram shows a Rubidium reference cell used to frequency stabilize a 780nm laser diode. The laser diode output frequency is adjustable by changing the diode temperature. The diode temperature is adjusted to get the laser diode very close to the absorption line of the Rubidium reference cell. The oscillator provides a reference for the Lock-In amplifier and modulation on the laser diode current supply. A beamsplitter directs a small part of the laser output energy through the Rb cell, and the detector output is used as an error signal to the Lock-in amplifier. The Lock-in amplifier and P-I control generates a DC valve to the current that keeps the output frequency centered on the peak of the absorption.
Molecular gas reference cells have a complex absorption profile. Gas molecules have a number of absorption lines due to vibrational-rotational transitions and due to these transitions make good frequency references in the wavelength range from 0.5 to 10 µm. These reference cells are made from Quartz and are filled with molecular compounds with a high purity level contained at a specific pressure. Molecular gas cells are often used as frequency standards; C2H2, HCN, and Carbon Monoxide (12C16O and 13C16O) were the gases chosen by NIST for their SRM series of frequency standards.
The reference cells are tested for optic throughput and fill material purity. Test setup:
Response from Javier at Thorlabs to a_chehrghai: Thank you for your feedback. The concentration specifications for the CQ09150-CO12 cell are the following: Carbon Monoxide (12C16O) Purity 99.99%. Impurities: Ar < 1 ppm, CO2 < 15 ppm, N2 < 200 ppm, THC < 10 ppm, N2 < 200 ppm, THC < 10 ppm.
Poster: a_chehrghai
Posted Date: 2010-07-21 04:31:58.0
what is the concentration (in ppm) of CO refference gas cell (600 torr-150 mm)?
Poster: a_chehrghai
Posted Date: 2010-07-21 04:29:45.0
what is co refference gas cell concentration (600 torr - 150 mm)?
Poster: Laurie
Posted Date: 2009-10-12 17:12:38.0
Response from Laurie at Thorlabs to lsandstrom: We have increased the quality of the graphs on our website so that they are now readable.
Poster: klee
Posted Date: 2009-10-09 12:02:15.0
A response from Ken at Thorlabs to lsandstrom: We will send you the graphs with higher resolution.
Poster: lsandstrom
Posted Date: 2009-10-09 07:52:38.0
I can not read the text in the absorption graphs in the "graph tab" Do you have a table with the absorption lines that you can provide?
The GCH25-75 reference cell heater (holder) is designed to elevate the temperature of the gas in the cells up to 50 °C by using a built-in heating element. Thorlabs' TC200 temperature controller (sold separately) is the ideal controller to maintain the heater temperature. Each heater ships with cables to connect directly to the TC200. Adapter rings are included to allow the user to mount our standard gas reference cells.
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CP25075-CS
- Ref. Cell, Pyrex Ø25 mm x 75 mm, Cesium [Cs]
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