Polarization beamsplitter cube split randomly polarized beams into twp orthogonal, linearly, polarized components-S-polarized light is reflected at a 90°. Angle while P-polarized light is transmitted. Each beamsplitter consists of a pair of precision high tolerance right angle prism cemented together wieh a dielectric coating on the hypotenused of one of prism.
|Material:||N-BK7; Fused Silica|
|Parallelism:||＜20 seconds||＜5 seconds|
|Flatness(per 25.4mm):||λ/4@ 632.8nm||λ/10@ 632.8nm|
|T/R(for random porlarization)T=(Ts+Tp)/2；R=(Rs+Rp)/2:||50/50±5%||50/50±2%|
|Bevel(face width×45°) :||Protective bevel or specified by customer|
|Coating:||Range of the wavelength specified by customer|
|Part No.||Norrow Band||Broadband||Size|
|BRD-PBS-3.2||355nm, 488nm, 532nm,|
850nm, 880nm, 980nm,
1064nm, 1310nm, 1550nm
|3.2mm x3.2mm x3.2mm|
|BRD-PBS-5||5mm x 5mm x 5mm|
|BRD-PBS-10||10mm x 10mm x 10mm|
|BRD-PBS-12.7||12.7mm x 12.7mm x 12.7mm|
|BRD-PBS-15||15mm x 15mm x 15mm|
|BRD-PBS-20||20mm x 20mm x 20mm|
|BRD-PBS-25.4||25.4mm x 25.4mm x 25.4mm|
When the interference film is used for oblique incidence, a strong polarization effect is produced, especially for the interference film layer in the closed glue prism. This effect is due to the requirement that the tangential components of the electric and magnetic fields at each interface of the film layer be continuous. For S-polarized light, the electric field is perpendicular to the incident interface, and the effective refractive index of each layer is equal to the actual refractive index multiplied by the cosine of the respective refraction angle; for P-polarized light, the electric field is parallel to the incident interface, and the effective refractive index of each layer is equal to the actual refractive index. Except for the cosine of the respective refraction angle. Because of this, we have also designed various types of polarization beamsplitters using this polarization effect.
The design principle of the polarizing beam splitter is to find an incident angle. When a pair of parallel rays is incident at this angle, the reflectivity of the substrate and the film to the P-polarized light is the same. This special angle is called the Bouchers. Special angle. Under this condition, the reflectance of the P-polarized light completely disappears, and the multilayer film stack formed by alternately superimposing the two materials will not cause any reflection to the P-polarized light.
For practical film materials, this condition can only be achieved when light is incident on a multilayer film from a high refractive index medium. Therefore, such a multilayer film is usually glued in the middle of a glass prism. Therefore, only the effective refractive indices of P-polarized light are equal, and two different materials can satisfy the Brewster angle condition.
When the effective refractive index: nL / cosq L = nH / cosqH
And in accordance with the law of refraction: nL*sinq L=nH*sinqH= no*sinq o
Namely: no*sinq o=nH*nL/(n2H+ n2L) 1/2
In this way, the design and preparation of the polarization beam splitting prism can be easily realized by specifying the refractive index of the high and low materials, selecting the angle of the glass substrate or specifying the incident angle of the glass substrate.
The following curves are designed with nb2o5 and sio2 at 45 degrees of incidence: