Fig. 2. With given image (scene) calculation of hologram
means determination of a complex amplitude field in the plane of a hologram
followed by calculation of an effective phase field in hologram plane
will be obtained owing to interference. But as was mentioned
above, the possibilities to change simultaneously both the amplitude and
phase we are restricted. Practically one can manipulate with a phase or
with amplitude only. The technology [6,7] allows producing a given relief
in a transparent material therefore we deal with the phase DOE.
We developed a method of calculating an effective phase
field from the complex amplitude. The method produces the phase field in
form of a 4-level phase hologram. Details of the method including
estimation of effectiveness of a 4-level hologram will be presented
elsewhere. Of importance here is that the effective phase field is
directly related to the relief via the refraction index of a DOE material.
The analysis of relieves and our experimental experience show that the
relief has spatial features with sizes from 100nm to 10um. This was the
reason why e-beam lithography (not a photolithography) was used for DOE
producing. in [4,5].
The technology of DOE producing is described in [6,7]. The main advantage of the technology is the fact that only one e-beam exposure
it used. This became possible after and due to the development of a special 3D proximity correction technique [6,7]. The possibility of the
given relief creation was demonstrated by producing lenses with a continuous relief . Further we developed additional technological steps
to produce a rigid copy from the resist relief and to obtain copies of the relief from soft material . We estimated the spatial resolution of the
whole technological chain to be 50nm. This estimation was confirmed in  where resolution 25nm was achieved during imprinting in polymer
Fig.3e. An AFM image of a relief of a transparent polymer DOE after copying from the metal replica.
Fig.3f. An image corresponding to the 4-level DOE. image resulting from the 4-level hologram.
Fig4.a. A DOE with two different focal planes.
Fig.4b. An image formed DOE (hologram) on distance = 2mm.
Fig.4c. An image formed by DOE (hologram) on distance = 3mm
The first example (Fig.3) comprises a passive splitter of a parallel
laser beam into tens of distinct beamlets. Fig. 3a shows a designed
image where the beamlets are arranged as some letters. An effective
4-level phase field is shown in the gray scale in Fig. 3b. The hologram
of 200um by 200um was calculate for PMMA with refractive index n=1.49
and for a laser with wave length l=632.8nm. An elementary height step
provides the 3.14../4 phase shift. Figure 3c demonstrates a 200um by
200um lithographic pattern consisting of about ten thousand domains
with specific exposure times assigned as result of the 3D proximity
correction implemented in the advanced version of PROXY. We used the
SEM JSM-840 as the exposure tool together with PROXY-WRITER for lithographic
data preparation and exposure control. After the exposure and development
4-level relief in resist was created. Electroplating with Cu was used
to obtain a rigid copy (a stamp) of the resist relief. The expected
4-levels of the metal are clearly seen in Fig. 3d. Several tens of polymer
copies were than obtained by imprinting in heated PMMA. A PMMA relief
of a polymer copy obtained by AFM is shown in Fig. 3e. The last picture
Fig. 3f presents a computer simulation of an image corresponding to
the 4-level DOE. image resulting from the 4-level hologram.
Fig.3a. A designed (desirable) image.
Fig.3b. A phase distribution (4 levels) of phase DOE to produce image the of Fig.3a.
Fig.3c. Exposure time isolevels after correction
Fig.3d. A SEM image of a metal replica from
resist relief (DOE) obtained by one step e-beam lithography and electroplating
The sizes of the beamlets and their relative intensities for
the image generated by real 4-level phase hologram were very close to
those predicted by simulation. This was demonstrated during the paper
presentation at MNE'96.
The second example demonstrates the possibility to create
not only image in the plane but 3D scene and comprises tens of focal
spotlets concentrated in two distinct focal planes as shown in Fig. 4a. In
this case a 200um by 200um hologram was created. Figure 4b and Fig 4c show
the corresponding images in two focal planes. The sizes and relative
intensities of the spotlets were consistent with the simulated
A method for designing of calculated holograms (DOEs) in
form of a 4-levels relief is presented briefly. The technological scheme
based on 3D proximity correction, one step e-beam lithography and
electroplating for obtaining rigid stamp for further producing cheap
polymer copies of DOE is experimentally evaluated. Two demonstrators
(passive splitter and generator of 3D scene) confirm the reliability of
the whole long set of designing and technological steps.
1.T.Shiono, K.Setsune, O.Yamazaki and K.Wasa.
J. Vac. Sci. Technol. B 5.33(1987)
2.T.Shiono and H.Ogawa, Appl. Opt.
3. M T Gale,M Rossi H Schulz, Proceedings of the Foruth
International Conference on 'Holographic Systems, Components and
Applications', 13-15 September 1993, University of Nuechatel,
4.H.Zarzhitsky, A.Stemmer, F.Mayerhofer, and G.Lefranc.
Jpt. Eng. 33.3527(1994)
5.A Stemmer, H.Zarzhitsky, E.Knapec, G.Lefranc,
and F.Mayerhofer. J.Vac.Sci.Technol. B 12,3635(1994)
B.N.Gaifullin, V N Matveev, H.F.Raith, A.A.Svintsov, and S.I.Zaitsev, J.
Vac. Sci. Technol. B 13(6) Nov/Dec 1995, 2526.
7. V V Aristov,
S.V.Dubnos, R Ya Dyachenko, B.N.Gaifullin, H.F.Raith, A.A.Svintsov, and
S.I.Zaitsev, Microelectron. Eng. 27, 195(1995)
8. S Y Chou, P R Krauss,
P J Renstrom, Science, Vol. 272, 5 April 1996, P 85.