Beam Splitters For Intensity, Alignment, And Interferometry
Below are some featured Coatings where customers wanted to split the beam intensity for various applications
Plate - ESO/ Cascade BS T/R=30/70% 2.8-5µ (L&M Band) @ 20º
In this particular case the Astronomer wanted to split up the intensity for two reasons: The customer wanted to utilize a filter to create neutral density across both the L and M band and to utilize 30% of the light to align the device. It was also important to them to minimize polarization effects. This IR coating was coated on ZnSe. Due to the high index of ZnSe there was also an AR on the back side
Cube - Rs/Ts=50/50%±1% 680-780nm Cube BS
This customer wanted a very flat BS from 670-800nm for an Interferometer. Due to the internal angle of incidence, the cemented gap and index difference between, the coating materials and Bk7 cube there are heavy polarization effects. Accordingly, we recommended an S-Polarization preference. With this preference we were able to maintain their tight 1% tolerance. In this particular example the customer was not interested in Tp
Plate - R >99% @ 1310, Rav < 3% @450-650, & R = T = 50% ±3% @ 1064 nm @ 45º
The US Navy wanted quite a challenging and multi-faceted BS design for MW range 1064nm Laser Power. Although the exact purpose of this optical element is not publicly know, it is clear this optic is unique and highly classified
Plate And Cube Polarizer
It may be necessary to polarize light in order to "clean up" a signal and obtain a better Signal To Noise ratio(S/N). This can be especially important in fiber optics or optics where the signal is carried over large distances. We are able to achieve Tp/Ts>1000 over a very broad range
Plate - POL For Telecom 1550nm C Band at Brewster's Angle
This Telecommunications company sought out our services to Polarize light that would be coupled into PM or Polarization Maintaining Fiber. In this case, the customer did not really have a specific angle of incidence in mind. So, Cascade suggested we utilize the Brewster's angle to facilitate the best possible Tp Transmission while the coating design's interference layers went to work on reflecting the remaining Ts. This angle is 56.13º for air to FS. Here we see Tp is maximized and Ts is -37db or 0.02% reflectivity or Efficiency of Tp/Ts>5000 which is excellent for a Plate BS
Plate - POL for VIS and NIR
This customer works in the Biosciences and has a product that replaces human eye lenses after cataract eye surgery. For their particular application they requested a VIS Pass and then a secondary POL at 850nm
Cube - BS Ts/Tp>60db Telecom S, C,& L Band
With a high internal angle of incidence and a large Cube and coating material index offset very large polarization effects are induced. So, It takes fewer layers than a Plate to Reflect Ts. For the same reason, the wave band is typically much broader than a Plate. The other benefit is there is no beam displacement. But, again, transparency is limited by optical cements. For some IR applications, it may be necessary to create >lambda/20 flat Hypotenuses and contact them under vacuum
In some ultra, extreme applications the Extinction coefficient, defined as the ratio between Tp and Ts has to be as high as 100,000. The plot to the right shows performance of the Cube BS designed for S, C and L Telecom bands having a Ts to Tp, staggering, ratio of more than 60db