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Optical 45°-Beamsplitters

Special Characteristics

  • Colour-neutral division of light and images
  • Back side anti-reflection coated
  • No ghost images or "ghosting" effects
  • Dielectric coating design with low light loss
  • Based on a non-metallic thin film layer construction
  • Made for random polarization
  • High optical quality
  • Very large dimensions available (DST500)

Typical Applications

  • Efficient splitting of light-beams and images
  • 45°-laser beamsplitters for up to medium laser power
  • Optical reference measurement systems
  • Semi-transparent optics for interferometer systems
  • Sensor technology
  • Plate beamsplitters for fiber optical applications
  • Teleprompter-mirrors
  • Photonics research
  • Laser beam-combiners
  • Beamsplitter plates in optical measuring instruments
  • LED measurement technology
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Our optical plate beamsplitters of the DST-series split 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 thin film coating which determines the division ratio. On the back side there is a broadband multi layer anti-reflection coating to prevent secondary reflections. This AR-coating almost completely suppresses so-called "ghost images" and phantom laser beams in the visible wavelength range. Hence, losses and image overlays caused by reflections from an uncoated glass back side do not occur.

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

A non-metallic construction of the coatings ensures durability and good abrasion resistance. Furthermore, the dielectric layer system of the semi-transparent mirrors only has very low absorption in the nominal wavelength range. Therefore almost no of energy is lost caused by absorption effects as it is typical for metal based beam splitting optics.

As substrate materials for the DST series we use iron-reduced glasses. Its low-loss design allows the beamsplitters to be used for laser applications up to medium laser power.

Flat laser beam dividing opticsAll DST beamsplitters are designed for unpolarized light. The polarization directions of all photons in an unpolarized light beam are uniformly distributed which is not the case for polarized light beams. So when used with polarized light or a polarized laser beam, the splitting ratios of the DST-plate beamsplitters may vary from the specifications given. The division ratios in this data-sheet are defined only for random polarization which means that all DST beamsplitters are undefined with respect 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 random polarized light. Costs can drastically be reduced compared to a customer-specific coating batch in such cases.

If you search for a beamsplitter for polarized light or a polarized laser beam please let us know the 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 batch basis.

In addition to our standard optical beamsplitters DST300, DST500, and DST700, the division ratios can be adapted to custom specifications. From a certain batch size 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. Such special optics are always manufactured according to customer's requirements. They are therefore not 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 a specialty beamsplitters.


How can I purchase the DST beamsplitters?

We are specialized in rapid manufacturing and delivery of our DST-beamsplitters with custom dimensions. Usually we deliver custom dimensions just as fast or even faster than stock items with fixed dimensions can be delivered by the competition. 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 perfectly fits in your application. So no need for a shopping cart.


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


Request for Quotation



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"