Next: Laser lithography
Prepared As-S thin film samples were used as a medium for
classical holographic recording and for laser lithography (laser
writing). Some of the exposures were done at IPHT Jena during
visit(s) there, due to unique optical equipment available, the
rest was done in-house.
The holographic recording setup in IPHT Jena was situated on
vibrations isolating Melles Griot optical table with air
suspension mechanisms. The setup itself is depicted on
fig. 17. The continuous wave Ar laser
COHERENT INNOVA model 304 served as the main recording beam
source. The used wavelength was 514.5 nm. The laser was equipped
with intra cavity etalon and the gaussian beam diameter was about
1.2 mm. The coherence length of this laser is on the order of tens
meters so this factor can be neglected.
The beam was controlled by 845 HP-02 remote-controlled electronic
shutter system by Newport to prevent touching the optical table.
Than the beam height adjusting system comprising of set of two
mirrors was used. The Newport beamsplitter was used to split the
beam into two. Two halfwave plates were used to control and adjust
the outgoing beams ratio. Two Newport spatial filters were used to
remove random fluctuations from the intensity profile of the laser
beams. The schematic drawing of a spatial filter is on the
figure 19. Two lenses were used to make the
expanded beams parallel.
All of mirrors (Newport) used in the recording setup were models
with extremely high surface flatness () and
reflectivity, which results into a low wavefront distortion. They
were placed on massive steel mounts to prevent vibrations and any
motion. To control the beams diameters last components before the
sample stage were two iris diaphragms.
A beamblocker was located just behind a sample to protect
operators. Beams ratio has been checked regularly and adjusted to
be as close as possible to 1:1. Beam intensity was about 100
mW/cm in each of two beams. The Newport hand-held Optical
Power meter 840-C, with Newport 818-SL visible range silicon
detector was used for these measurements. This detector is
equipped with EEPROM calibration module compatible with power
Holographic recording setup used at IPHT Jena
1 Arlaser COHERENT INNOVA 304; 2 He-Ne laser
HN-40P-1; 3 Electronic Shutter; 4 Beamsplitter; 5 Spatial Filters;
6 Collimating Lens; 7 Dielectric Mirrors; 8 Iris Diaphragms;
9 Sample stage; 10 Mechanical Shutter; 11 Photodetector Newport
The setup used in our laboratories is similar to that one used in
Jena. Our setup is shown on fig. 18 The whole
setup is also placed on an optical table, as vibrations
isolating/reducing component is used thick (15 cm) layer of soapy
polystyrene. The recording beam source is Ar laser system
ILA-120-1 with water-cooling system by Carl Zeiss corp. The
Newport dielectric mirror is then used to change beam direction.
The beam is interrupted by 845 HP-02 remote controlled electronic
shutter system by Newport to minimize operator-table contact time.
On the stable fixed height platform are a Newport beamspliter cube
and again two spatial filters to improve beams profiles and
Holographic recording setup built at
Description: 1 Arlaser ILA-120-1;
2 Electronic Shutter; 3 Beamsplitter; 4 Spatial Filters;
5 Collimating Lens; 6 Dielectric Mirrors; 7 Iris Diaphragms;
8 Sample stage
Two achromatic lenses are used to make the beams parallel again.
Three additional mirrors are used to redirect beams. All used
mirrors are Newport VALUMAX models with dielectric
coating and very high () surface flatness to prevent
wavefront distortion. Two iris diaphragms are used to control the
final diameters of the beams.
Various exposure times were tested on both setups as well as
various recording angles. Applying equation 17 on
page , it is possible to calculate
different recording periods obtained.
Schematic drawing of a
Spatial Filter 
Next: Laser lithography