Thin-film interference filters are usually the ideal solution for wavelength selection in optical systems, due to their exceptionally high transmission, very steep spectral edges and blocking over OD6 or higher over wide spectral regions for maximum noise suppression. Until now though, they have had one major drawback: they are essentially fixed in their spectral characteristics. Semrock 's revolutionary new Versachrome filter changes all this. Now for the first time: thin film filters that are tunable over a wide range of wavelengths, simply by adjusting the angle of incidence, and with essentially no change in spectral performance. Wide tunability is possible, up to 60°, for both edge and bandpass filters, as shown below.

The Versachrome filter was one of the ten winners of the Second Annual Microscopy Today Innovation Awards. Contact us today to learn more, or for more detailed local pricing. Or click for further information, including a discussion on Spectral Imaging with VersaChrome Filters, below. 

Spectral Imaging with VersaChrome Filters

Conventional spectral imaging systems are generally not able to offer the key advantages of thin-film interference filters, i.e., high transmission combined with steep spectral edges and high out-of-band blocking. Now with VersaChrome filters, these advantages can be realized in simple spectral imaging systems for applications ranging from fluorescence microscopy to hyperspectral imaging.

To demonstrate spectral imaging in a fluorescence microscope, a “lambda stack” of images (corresponding to a nearly continuous series of emission wavelengths) was acquired of a sample labeled with three spectrally overlapping fluorophores using a Semrock VersaChrome tunable filter (TBP01-620/14) placed in the emission channel of a standard upright microscope. Figure 1 shows six of the 61 images taken at 1 nm intervals, and Figure 2 shows measured intensity spectra taken from parts of the image where only a single fluorophore is present. The nucleus labeled with SYTOX® Orange can be easily discriminated from the other cellular structures (Fig. 1). However, since the F-actin and mitochondria are labeled with fluorophores that are highly overlapping (Alexa Fluor™ 568 and MitoTracker® Red, respectively), linear unmixing is necessary to discern the corresponding cellular constituents. Images deconvolved with linear unmixing are shown in Figure 3.

It is important to note that the spectral properties of these tunable filters are almost identical for both s and p polarizations of light – a feature that cannot be easily obtained using liquid-crystal and acousto-optic tunable filters. Polarization independence is highly desirable for spectral imaging systems, and yet polarization limitations of current tunable filters account for a loss of at least half of the signal in most instruments. Therefore VersaChrome filters not only enhance the throughput in spectral imaging but they also greatly simplify the complexity of instrumentation.

Figure 1

Figure 2

Figure 3.

http://www.semrock.com/spectral-imaging-with-versachrome-filters.aspx

ABOUT SEMROCK
Semrock, Inc., a Unit of IDEX, manufactures optical filters that set the standard in performance and reliability for the biotech and analytical instrumentation industries, as well as innovative optical filters for more general laser and optical systems applications. All Semrock optical filters are made with hard ion-beam-sputtered optical coatings. OEM filters are manufactured in volume. End-users benefit from a wide selection of standard catalog products that ship from stock. Semrock's patented and patent-pending products include its highly acclaimed BrightLine® fluorescence filters, state-of-the-art filters for Raman spectroscopy, and other unique filters for lasers and optical systems. Semrock's innovative products, made possible by combining modern ion-beam sputtering with Semrock's proprietary volume manufacturing technology, are covered under a five-year warranty.

Founded in September 2000, Semrock is based in Rochester, New York.