Del Mar Photonics
J. Chem. Phys. 133, 044308 (29 July 2010)
Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers: A novel technique for ultratrace gas analysis and high-resolution spectroscopy
Michael Hippler1, Christian Mohr1, Katherine A. Keen2, and Edward D. McNaghten2
1Department of Chemistry, University of Sheffield, Sheffield S3 7HF, United Kingdom
Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers (OF-CERPAS) is introduced as a novel technique for ultratrace gas analysis and high-resolution spectroscopy. In the scheme, a single-mode cw diode laser (3 mW, 635 nm) is coupled into a high-finesse linear cavity and stabilized to the cavity by optical feedback. Inside the cavity, a build-up of laser power to at least 2.5 W occurs. Absorbing gas phase species inside the cavity are detected with high sensitivity by the photoacoustic effect using a microphone embedded in the cavity. To increase sensitivity further, coupling into the cavity is modulated at a frequency corresponding to a longitudinal resonance of an organ pipe acoustic resonator (f = 1.35 kHz and Q ≈ 10). The technique has been characterized by measuring very weak water overtone transitions near 635 nm. Normalized noise-equivalent absorption coefficients are determined as α ≈ 4.4×10−9 cm−1 s1/2 (1 s integration time) and 2.6×10−11 cm−1 s1/2 W (1 s integration time and 1 W laser power). These sensitivities compare favorably with existing state-of-the-art techniques. As an advantage, OF-CERPAS is a “zero-background” method which increases selectivity and sensitivity, and its sensitivity scales with laser power.
CW Ti:Sapphire laser used in intracavity laser absorption spectroscopy - request a quote
Del Mar Photonics - Newsletter December 2010 - Newsletter April 2011
Del Mar Photonics featured optical components
Del Mar Photonics continuously expands its optical components portfolio. Browse our online store, read monthly notes about our featured optical products or just send us your requirements or product ideas.
Axicon lens also known as conical lens or rotationally symmetric prism is widely used in different scientific research and application. Axicon can be used to convert a parallel laser beam into a ring, to create a non diffractive Bessel beam or to focus a parallel beam into long focus depth.
Del Mar Photonics supplies axicons with cone angles range from 130° to 179.5° for use with virtually any laser radiation. We manufacture and supply axicons made from BK7 glass, fused silica and other materials.
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Rutile (TiO2) coupling
Del Mar Photonics offers optical elements made of high quality synthetically grown Rutile Titanium Dioxide crystals. Rutile’s strong birefringency, wide transmission range and good mechanical properties make it suitable for fabrication of polarizing cubes, prisms and optical isolators. Boules having high optical transmission and homogeneity are grown by proprietary method. Typical boules have 10 - 15 mm in dia. and up to 25 mm length. Optical elements sizes - from 2 x 2 x 1 mm to 12.7 x 12.7 x 12.7 mm. Laser grade polish quality is available for finished elements. So far we the largest elements that we manufactured are 12 x15 x 5 mm, in which optical axis is parallel to 15 mm edge, 5 mm is along beam path, 12 x 15 mm faces polished 20/10 S/D, one wave flatness, parallelism < 3 arc.min. (better specs. available on request).
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Del Mar Photonics offer a range of competitively priced UHV viewports , Conflat, ISO or KF including a variety of coatings to enhance performance. Del Mar Photonics viewports are manufactured using advanced techniques for control of special and critical processes, including 100 percent helium leak testing and x-ray measurements for metallization control. Windows Materials include: Fused silica, Quartz , Sapphire , MgF2, BaF2, CaF2, ZnSe, ZnS, Ge, Si, Pyrex. Standard Viewing diameters from .55" to 1.94 ".
Coating - a range of custom coatings can applied - which include
- Single QWOT
- Broad Band AR
- V coatings
- DLC (Diamond like coating)
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Manufacturing challenging optical components
Our group works to characterize the interaction of biomolecules with solid surfaces, writes Dennis Hore of University of Victoria, Canada. Nature designs proteins with well-defined structures in solution. The conformation of these molecules may serve a structural purpose, or a chemical one in the case of enzymes. In order to further the progress of technologies that immobilize such molecules on synthetic surfaces (like biosensors employing enzymes), it is important to have a detailed understanding and control of the interactions of these molecules with the surface more
For that project Del Mar has been able to manufacture all shapes of prisms from CaF2, fused silica, and ZnSe according to our custom specifications.
Del Mar Photonics online store features windows, prisms, lenses, attenuators, etalons, crystals and wafers, and other items. Axicons, barium fluoride windows, germanium etalons, rutile (TiO2) prisms, microchannel plates and detectors, saturable absorber mirrors, photoconductive THz antennas, lithium niobate wafers and crystals and many other high quality affordable components for scientific research and OEM production are delivered globally from stock.
Micro Prism from Del Mar Photonics - Concentrating Photovoltaics
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Trestles LH femtosecond lasers with integrated DPSS DMPLH laser pump - DPSS DMPLH lasers