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Wavelength	Splitting Ratio
250 - 450 nm	50:50
350 - 1100 nm	50:50
400 - 700 nm	10:90	30:70	50:50	70:30	90:10
600 - 1700 nm	50:50
700 - 1100 nm	10:90	30:70	50:50	70:30	90:10
0.9 - 2.6 μm	50:50
1.0 - 6.0 µm	50:50
1.2 - 1.6 μm	10:90	30:70	50:50	70:30	90:10

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Item number is engraved on beamsplitting surface, when available.

Features

• 25 mm x 36 mm Rectangular Plate Beamsplitters Designed for our Microscopy Filter Cubes
• Available for Multiple Wavelength Ranges Between 250 nm and 6.0 µm
• Certain Wavelength Ranges Offer Multiple Split Ratios (R:T) for AOI = 45°
• 1 mm Thick Substrates

When performing reflected light microscopy, a beamsplitter directs light from an illumination source to a sample while simultaneously transmitting the light reflected by the sample onto the image plane. Thorlabs offers Non-Polarizing Plate Beamsplitters at varying wavelengths and beam splitting ratios for ultravoilet (UV), visible, near infrared (NIR), and mid-infrared (MIR) applications.

These rectangular beamsplitters, measuring 25 mm x 36 mm x 1 mm, have a dielectric beamsplitter coating deposited on the front surface. The beamsplitter dimensions match our dichroic mirrors commonly used in microscopy, making them compatible with our microscopy filter cubes and other rectangular filter holders. Thorlabs also offers a complete selection of non-polarizing plate beamsplitters in round diameters and for additional wavelength ranges.

The majority of these beamsplitters are fabricated using a UV fused silica or an IR fused silica substrate, both of which offer superior homogeneity and a lower coefficient of thermal expansion than N-BK7 glass. In addition, UV fused silica exhibits high transmission deep into the UV with virtually no laser-induced fluorescence, making it an ideal choice for applications from the UV to the near IR. For performance in the MIR, our 1.0 - 6.0 µm beamsplitter is made from Calcium Fluoride. 

To reduce the effect of ghost images, an antireflection (AR) coating, which is designed for the same operating wavelength range as the beamsplitter coating on the front surface, has been deposited onto the back surface of a selection of our beamsplitter. By applying an AR coating to the back side of the beamsplitter, the percentage of light reflected back through the front surface is reduced to an average of less than 1% over the entire operating range of the coating. To differentiate between the front and back surfaces, the beamsplitter surface is indicated with the Item # engraving, as shown in the image above.

Mounting Options
For customers who wish to use these beamsplitters in microscopy applications, Thorlabs manufactures a family of filter cubes and mounts. Additionally, these beamsplitters can be mounted in the KM2536 kinematic mount, which is designed to secure 25 mm x 36 mm rectangular optics with minimal stress.