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Optical 45°-Beamsplitters

Special Features

  • Color neutral splitting of light and images
  • Anti-reflection coated back side
  • Free of ghost images or "ghosting" effects
  • Dielectric low-loss coating design
  • Non-metallic thin film layers
  • Made for random polarization
  • High optical quality
  • Large dimensions available (DST500)

Typical Applications

  • 45°-beamsplitters for up to medium power laser beams
  • Optical reference measurement systems
  • Semi-transparent optics for interferometer systems
  • Optical sensor technology
  • Plate beamsplitters for fiber optical applications
  • Optics for photonics research
  • Beamsplitter plates in optical measuring instruments
  • Laser beam-combiners
  • LED measurement technology
  • Divider mirrors for imaging applications
  • Teleprompter-mirrors
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Our high-quality, optical plate beamsplitters of the DST series split the incident light into a transmission and a reflection component. A light beam, an image, or a laser beam are partially reflected, as by an optical mirror and partially transmitted, as through an optical window.

Plate beamsplitters used as laser beam dividerThe input side of the 45° beam splitter plates is coated with a dielectric, optical thin film which determines the splitting ratio of the optics. On the back of the beam splitter there is a broadband multilayer anti-reflection coating that suppresses secondary reflections. These AR-coatings almost completely eliminates so-called "ghost images" and phantom laser beams in the visible wavelength range. Hence, optical losses and image overlays otherwise caused by reflections from an uncoated glass back side nearly do not occur.

Unlike dichroic beamsplitters like our SIR Hot Mirror or the SHD cold-mirrors, our DST beamsplitter products have a non-dichroic design. Thus, they do not separate different optical spectra from each other and they do not filter out wavelength ranges, but split incident light rays in the visible spectrum to a large extent color-neutral.

A non-metallic, purely dielectric design of the optical coating ensures durability and a good abrasion resistance. Moreover, the layer system of our semitransparent mirrors only shows a very low absorption in the nominal wavelength range. Therefore, almost no energy is lost through absorption effects, as is typical for metallic beam splitter optics, for example. The low-loss design allows the beamsplitters to be used for laser applications up to medium laser power. As substrate materials for the DST optics we use iron-reduced glasses with excellent optical characteristics.

Flat laser beam dividing opticsAll DST beamsplitter optics are designed for unpolarized light. The polarization directions of the photons in an unpolarized light beam are uniformly distributed which is not the case for polarized light beams. So when used with a polarized light- or laser beam, the splitting ratios of the DST-plate beamsplitters may vary from the nominal values which are given for unpolarized sources. The DST beam splitters are not specified with regard to polarization behavior or polarization effects. This however, does not exclude applications with polarized light. Often the desired splitting ratio can simply be achieved by choosing an existing higher or lower nominal division ratio for randomly polarized light. The costs in such cases can drastically be reduced compared to a custom coating batch. However, if you search for specialty beamsplitter optics for polarized light or a polarized laser source please let us know the desired specifications. In the case of special requirements for the polarization properties in most instances we are capable of fabricating customer-specific polarization-optimized beamsplitter optics on a coating run basis.

In addition to our standard beamsplitter series DST300, DST500, and DST700, the splitting ratios can be adapted to custom specifications. From a certain batch quantity upwards we can also produce cube beam splitters, beam splitter penta-prisms, NIR dividers, and high-performance beamsplitters. Design and manufacturing of polarizing beam splitter cube optics as well as of polarization obtaining cube beam splitters can also be realized. Please take into account, that such special optical components are always manufactured according to customer's requirements. Hence, these components cannot be listed in detail in our website. So if you search for such kind of optics, please use our inquiry form to request a quote for such specialty beamsplitters.


How can I purchase the DST beamsplitters?

We are specialized in rapid manufacturing and delivery of our beamsplitters with custom dimensions. Usually we deliver custom dimensions just as fast or even faster than stock optics with fixed dimensions can be shipped. This also and particularly applies to large production quantities. If you are in our time zone and there are no queries, you normally will receive our quotation within a few minutes. Our goal is that you get what you need, so that the beam splitter optics perfectly fit into your application. You will therefore not find a shopping cart on our website.


To request an offer for one of our optical DST beamsplitters with freely defined dimensions, please click on the button below.


Request for Quotation

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DST300, transmittance

DST300, spectral transmittance curve for visible wavelengths

DST300 at wavelength 400-700 nm


DST500, transmittance

DST500, typical transmittance for visible wavelengths

DST500 at wavelength 400-700 nm


DST700, transmittance

DST700, typical spectral transmittance for visible light

DST700 at wavelength 400-700 nm


Product Codes

(Reflection (R) : transmission (T),
defined for unpolarized light beam)
  • DST300 (R : T = 70 : 30)
  • DST500 (R : T = 50 : 50)
  • DST700 (R : T = 30 : 70)
  • Other division ratios and incident angles possible on demand

Substrate Materials

Optical Coating Definitions

(Incidence angle i = 45° / random polarization)

  • R : T = 70 : 30 (± 10%) at wavelengths
    of 450-650 nm
    (Typical conditions for laser use on request)
  • Rear side with broadband BBAR
  • Stock thickness 1,00 mm (+/-0,1)
  • R : T = 50 : 50 (± 6%) at wavelengths
    of 450-650 nm
  • R : T = 50 : 50 (± 10%) at 430-685 nm
    (Typical ratios for laser use on request)
  • Rear side with broadband AR
  • Standard thickness 1,00 mm (+/-0,1)
  • R : T = 50 : 50 (± 10%) at wavelengths
    of 450-650 nm
    (Typical ratios for laser use on request)
  • Rear side with broadband AR-coating
  • Stock thickness 3,30 mm (+/-0,2)
  • R : T = 30 : 70 (± 8%) at wavelengths
    of 450-650 nm
  • R : T = 30 : 70 (± 10%) at 400-700 nm
    (Typical ratios for laser use on request)
  • Rear side BBAR-coated
  • Stock tk. 1,00 mm (+/-0,1)


  • Depending on material, thickness, and shape
    (Flat, cube, prism, etc.)

Damage Threshold

  • Depending on laser beam diameter and laser power (Please send an inquiry if relevant)

Surface Quality

  • Typically better than 80-50 scratch & dig
  • Other per inquiry


  • up to approximately 630 mm x 810 mm
    (Flat beamsplitter optics only. Cube-, polarizing-, non-polarizing-, or prism-beam splitters, etc. are not feasible with such large dimensions. Please discuss the limits with our engineers.)

Other Specifications

  • Adherence according to MIL-C-675 C (tape test)
  • Abrasion resistance referred to MIL-M-13508 C


All given details and specifications are mean reference values and are not guaranteed. In addition please consider our "Notes on technical specifications"