Download THz Diffractive Optical Elements Datasheet (PDF, 119 KB) 
Beam handling is required in many THz applications. Currently it is carried out by parabolic mirrors and refractive optics. However diffractive optics opens up new, basically different opportunities of beam handling since it allows realizing spatial transformation of THz beam.
To satisfy needs in diffractive optics for THz range we have developed calculation methods and manufacturing technology of the following diffractive optical elements (DOE):
Commom Specification:
Parameters 
Type of DOE  
THz Fresnel lens 
THz beam divider 

Material  HRFZSi  HRFZSi 
Mechanical diameter, mm  to 55  to 55 
Optical diameter, mm  to 50  to 50 
Thickness, mm  1  1 
Operating wavelength range, µm  60250  60250 
Diffraction efficiency*, %  40  80 
Coating  twoside antireflection  twoside antireflection 
Developed DOEs have twolevel relief. Currently we are working at technology of DOE manufacturing with four and eightlevel relief. Multilevel relief will increase diffraction efficiency up to 96%.
THz Fresnel Lenses
Fresnel lens is the simplest diffractive element for focusing monochromatic beam. It has no spherical aberrations in comparison with refractive lenses.
There are two focal lengths of diffractive lens: the main one and the secondary one. Diffraction efficiency of the main focus I1/I is 40% and of the secondary one I2/I is <3.6% that has been confirmed experimentally**. Optical characteristics have been investigated using free electron laser, radiation has been detected by matrix microbolometer.
It's possible to produce the lenses with focal length from 100 mm and more. Focal length tolerance is 5%.
Dimension of Airy disk can be calculated using the following equation: X=1.22*λ*F/D, where λ  operating wavelength, F  focal length, and D  optical diameter.
THz Beam Dividers
Beam divider transforms incident beam into spatially spaced several beams with specified power distribution.
Diffraction efficiency of the operating orders (+1 and 1) is 40(+/2)% and of other orders <5%. Value of the angle between operating beams can be from 20deg to 80deg.
For quotation and delivery please fill in our request form.
__________________________** B. A. Knyazev, Yu. Yu. Choporova, V. V. Gerasimov, M. G. Vlasenko, V. S. Pavelyev, B. O. Volodkin , A. N. Agafonov , K. N. Tukmakov, A. K. Kaveev , G. I. Kropotov , E. V. Tsygankova , M. F. Stupak , I. G. Palchikova, Study of Diffractive Optical Elements Using HighPower Radiation of Novosibirsk Terahertz Free Electron Laser, Proceedings of IRMMWTHz 2012