Del Mar Photonics - Del Mar Photonics featured
customer Dennis Hore writes:
Our group works to characterize the interaction of biomolecules with solid
surfaces. 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.
We use a variety of optical techniques along with computer modeling to achieve
such a detailed molecular-level understanding. One of the
optical methods employed in our lab is a nonlinear technique: visible-infrared
sum-frequency generation spectroscopy. Here a fixed-wavelength visible (532 nm)
and tunable-infrared (2-10 microns) laser are spatially- and
temporally-overlapped at the solid-solution interface under investigation.
Under the right symmetry conditions, new photons are created with a frequency
that corresponds to the sum of the two incident frequencies. We then
characterize this new beam to work back towards the structure of the interface,
which in turn provides information on the adsorbed biomolecular structure. A
practical aspect of this experiment is that sample optics must be transparent in
the visible, and throughout the mid-infrared region.
For this we use calcium fluoride (CaF2) prisms. Del Mar Photonics has provided
high-quality prisms with custom shapes according to our drawings. One of the
photos shows a close-up view of our sample cell. It is an aluminum block with
internal plumbing for circulating water to maintain a constant temperature for
the experiment. Inside this block there is a teflon cell that contains the
analyte solution. An o-ring on the face of the cell interfaces to a CaF2 prism
which forms the prism-solution (solid-liquid) interface on which the
biomolecules are adsorbed. In the photo, one can see a hemi-cylindrical CaF2
prism in place. This allows the visible and infrared beams to be incident at
any angle, while maintaining a horizontal plane-of-incidence.
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A second experiment uses linear optical techniques to measure all 16 elements
of the 4x4 Mueller matrix of the solid-liquid interface.
This provides information on the surface roughness, thickness of the adsorbed
layer, complex dielectric constant, and any anisotropy. We
employ the same sample cell design for this experiment, using either 45-deg,
60-deg, or hemicylindrical prisms. In cases where the Mueller
matrix characterization is performed for visible wavelengths only, we use fused
silica prisms. For infrared-only measurements, we use zinc
selenide (ZnSe) prisms. Del Mar has been able to manufacture all shapes of
prisms from CaF2, fused silica, and ZnSe according to our
custom specifications.
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Dennis Hore
To request custom quote for precision optical component please e-mail us detailed specifications and drawings or check our online store for standard components available in stock:
| CaF2 | |
| Model | Product Name+ | Price | Buy Now |
| W-CF-25.4-3 | CaF2 window, ø 25.4 mm x 3.0 mm | $149.00 |
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| W-CaF-40-7 | CaF2 window, ø 40 mm x 7.0 mm | $450.00 |
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| W-CF-50.8-3 | CaF2 window, ø 50.8 mm x 3.0 mm | $190.00 |
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| DSP-CF-15 | Dispersion prism, IR grade CaF2, 15x15x15x10 mm | $150.00 |
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| Ge optics | |
| Model | Product Name+ | Price | Buy Now |
| E-Ge-12.7-25.4 | Ge etalon, ø 12.7 mm x 25.4 mm (ø 0.5" x 1") | $790.00 |
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| W-Ge-25.4-3 | Ge window, ø 25.4 mm x 3 mm | $110.00 |
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| W-Ge-38.1-4 | Ge window, ø 38.1 mm x 4 mm | $250.00 |
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| ZnSe | |
| Model | Product Name+ | Price | Buy Now |
| PH-ZnSe-25.4-12.7 | ZnSe hemicylindrical prism, 25.4 mm | $1,350.00 |
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| W-ZnSe-60-3-K | ZnSe window, ø60 mm, tckn. 3 mm, coated | $620.00 |
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| W-ZnSe-12.7-1 | ZnSe window, ø12.7 mm, thickn. 1 mm | $90.00 |
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| W-ZnSe-25.4-3 | ZnSe window, ø25.4 mm, thickn. 3 mm | $110.00 |
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| W-ZnSe-76.2-3-K | ZnSe window, ø76.2 mm, tckn. 3 mm, coated | $700.00 |
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| BaF2 - Barium Fluoride | |
| Model | Product Name+ | Price | Buy Now |
| WG-BF-25.4-10-1.55 | BaF2 wedge, 25.4 mm x 10.0 mm x 1.55 mm | $129.00 |
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| WG-BF-25.4-10-2.1 | BaF2 wedge, 25.4 mm x 10.0 mm x 2.1 mm | $129.00 |
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| WG-BF-25.4-10-2.5 | BaF2 wedge, 25.4 mm x 10.0 mm x 2.5 mm | $129.00 |
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| W-BF-12.7-2 | BaF2 window, ø 12.7 mm x 2.0 mm | $62.00 |
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| W-BF-4-0.5 | BaF2 window, ø 4" x 0.5", polished, uncoated | $1,200.00 |
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