Liquid crystal modulator in the channel of a laser projection microscope
Using the light modulator based on electrically controlled reflection in the interface between isotropic dielectric and nematic liquid crystal has been viewed. The optical scheme of a laser projection microscope (LPM) with a liquid crystal modulator (LCM) in treatment, observation and recording chan...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2004
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| Назва видання: | Semiconductor Physics Quantum Electronics & Optoelectronics |
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| Цитувати: | Liquid crystal modulator in the channel of a laser projection microscope / P. Oleksenko, V. Sorokin, R. Zelinskyy // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2004. — Т. 7, № 3. — С. 309-312. — Бібліогр.: 10 назв. — англ. |
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irk-123456789-1191312017-06-05T03:03:42Z Liquid crystal modulator in the channel of a laser projection microscope Oleksenko, P. Sorokin, V. Zelinskyy, R. Using the light modulator based on electrically controlled reflection in the interface between isotropic dielectric and nematic liquid crystal has been viewed. The optical scheme of a laser projection microscope (LPM) with a liquid crystal modulator (LCM) in treatment, observation and recording channels has been proposed, implemented and investigated. In the proposed scheme, LCM can act as a light beam splitter, attenuator and modulator simultaneously. Possibilities of some thin film materials processing by LPM with LCM in the treatment, observation and recording channels are demonstrated. 2004 Article Liquid crystal modulator in the channel of a laser projection microscope / P. Oleksenko, V. Sorokin, R. Zelinskyy // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2004. — Т. 7, № 3. — С. 309-312. — Бібліогр.: 10 назв. — англ. 1560-8034 PACS: 42.79.Hp http://dspace.nbuv.gov.ua/handle/123456789/119131 en Semiconductor Physics Quantum Electronics & Optoelectronics Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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Using the light modulator based on electrically controlled reflection in the interface between isotropic dielectric and nematic liquid crystal has been viewed. The optical scheme of a laser projection microscope (LPM) with a liquid crystal modulator (LCM) in treatment, observation and recording channels has been proposed, implemented and investigated. In the proposed scheme, LCM can act as a light beam splitter, attenuator and modulator simultaneously. Possibilities of some thin film materials processing by LPM with LCM in the treatment, observation and recording channels are demonstrated. |
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Article |
| author |
Oleksenko, P. Sorokin, V. Zelinskyy, R. |
| spellingShingle |
Oleksenko, P. Sorokin, V. Zelinskyy, R. Liquid crystal modulator in the channel of a laser projection microscope Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Oleksenko, P. Sorokin, V. Zelinskyy, R. |
| author_sort |
Oleksenko, P. |
| title |
Liquid crystal modulator in the channel of a laser projection microscope |
| title_short |
Liquid crystal modulator in the channel of a laser projection microscope |
| title_full |
Liquid crystal modulator in the channel of a laser projection microscope |
| title_fullStr |
Liquid crystal modulator in the channel of a laser projection microscope |
| title_full_unstemmed |
Liquid crystal modulator in the channel of a laser projection microscope |
| title_sort |
liquid crystal modulator in the channel of a laser projection microscope |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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2004 |
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http://dspace.nbuv.gov.ua/handle/123456789/119131 |
| citation_txt |
Liquid crystal modulator in the channel of a laser projection microscope / P. Oleksenko, V. Sorokin, R. Zelinskyy // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2004. — Т. 7, № 3. — С. 309-312. — Бібліогр.: 10 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
| work_keys_str_mv |
AT oleksenkop liquidcrystalmodulatorinthechannelofalaserprojectionmicroscope AT sorokinv liquidcrystalmodulatorinthechannelofalaserprojectionmicroscope AT zelinskyyr liquidcrystalmodulatorinthechannelofalaserprojectionmicroscope |
| first_indexed |
2025-07-08T15:16:43Z |
| last_indexed |
2025-07-08T15:16:43Z |
| _version_ |
1837092364387090432 |
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309© 2004, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
Semiconductor Physics, Quantum Electronics & Optoelectronics. 2004. V. 7, N 3. P. 309-312.
PACS: 42.79.Hp
Liquid crystal modulator in the channel
of a laser projection microscope
P. Oleksenko, V. Sorokin, R. Zelinskyy
V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, 41, prospect Nauky, 03028 Kyiv, Ukraine
Abstract. Using the light modulator based on electrically controlled reflection in the interface
between isotropic dielectric and nematic liquid crystal has been viewed. The optical scheme of
a laser projection microscope (LPM) with a liquid crystal modulator (LCM) in treatment,
observation and recording channels has been proposed, implemented and investigated. In the
proposed scheme, LCM can act as a light beam splitter, attenuator and modulator simultane-
ously. Possibilities of some thin film materials processing by LPM with LCM in the treat-
ment, observation and recording channels are demonstrated.
Keywords: liquid crystal, modulator, optical scheme, super radiant laser medium.
Paper received 04.06.04; accepted for publication 21.10.04.
1. Introduction
The appearance of laser techniques was initiated by mi-
croelectronic requirements. It turned out that laser tech-
niques enable to solve such tasks as adjustment of hybrid
microcircuits, quartz resonators and surface acoustic wa-
ve device parameters, correction of defects in chips when
checking their quality, photomasks in chip production,
etc. Laser technique has a lot of advantages in the follow-
ing fields: small zone of thermal influence, adjustment of
treatment depth, high productivity, possibility of treat-
ment at various stages of chip production and after them.
Some articles were devoted to investigations of laser
techniques and ways of their implementation [1,2]. The
technique for simultaneous treatment, registration and
observation based on super radiant laser medium is a
field of special interest.
For the first time, the idea to obtain image with am-
plified brightness by using laser active medium was pro-
claimed in [3]. Later in [4], the practical scheme of LPM
was described, and its characteristics were published. In
the following articles, a lot of possible schemes of LPM
where active medium was used not only for imaging in a
screen, but also for simultaneous treatment and observa-
tion of objects [5], have been proposed. One of such
schemes was implemented in the laser microprojector 09
VP-1000-02. Main characteristics of this laser micropro-
jector were reported in [6]. It is necessary to notice that
such type of microprojectors can be successfully used for
treatment of thin film electron devices and equipment:
photomasks, resistors, semiconductor structures, etc.
High frequency of laser pulses (8 kHz) in a copper
vapor laser causes considerable difficulties during the
execution of precision technological operations. In the
course of the laser treatment, it is necessary to have a
possibility of fast laser beam switching (switch on and
off) with frequencies comparable to the frequency of laser
pulses. In a correspondence with this requirement, inves-
tigations of optical emission LCM based on electrically
controlled reflection of the light on interface between glass
and nematic liquid crystal as an optical element of LPM
have been performed [7]. The main goal of this paper was
to research LPM characteristics that can be achieved
using LCM in observation, recording and treatment chan-
nels and its comparison with LPM characteristics with-
out LCM. Main characteristics of LPM with LCM in
observation and treatment channels were also investi-
gated.
2. Peculiar properties of LPM schemes with
LCM
An optical scheme of device for observation, recording
and treatment of objects is shown on Fig. 1. Optical
scheme of device for observation, recording and treat-
ment of objects with LCM in observation and recording
channels is shown in Fig. 2. It consists of super radiant
laser medium 1 with the optical focusing system 2 and
310
SQO, 7(3), 2004
P. Oleksenko et al.: Liquid crystal modulator in the channel of a laser projection microscope
object 3 on the one side. On another side of super radiant
laser medium 1 placed are LCM 4 and the reflective ele-
ment 5. In the plane n1, which is conjugated with the plane
n2, containing the object 3, located a recording medium
6, for example, screen for visual observation. Object 3 is
treated and observed by super radiant laser medium 1
that can be gas discharge plasma in vapors of copper,
gold, barium, etc. A thyratron generator can accomplish
excitation of superradiant laser medium. The light beam
from super radiant laser medium is collected at the object
3 by the optical focusing system 2.
It is necessary to notice that in the same time the light
beam falls on the recording medium 6. The light beam
reflected by the object 3 is returned through the optical
focusing system 2 in superradiant laser medium 1 where
it is amplified. After that, it comes into LCM light splitter
where it is divided into two parts. One part of the light
beam comes onto the recording medium 6 in order to ob-
tain an amplified brightness and magnified image of the
object 3. Another part of the light beam is reflected from
the element 5 and returns into the superradiant laser me-
dium 1 and falls onto the object 3 through optical focus-
ing system 2.
The object 3, optical focusing system 2, superradiant
laser medium 1, LCM light splitter 4 and recording me-
dium 6 located on the same optical axis form an observ-
ing channel. Respectively, object 3, optical focusing sys-
tem 2, superradiant laser medium 1, LCM light splitter 4
and reflective element 5 situated at the same optical axis
form the treatment channel. At the same time, LCM works
as alight splitter and optical shutter. It allows us to ac-
quire necessary object characteristics at the right time
moment.
The increase in treatment accuracy and quality, and
obtaining light spot with minimum size for the given op-
tical focusing system 2 has been achieved because the
dimensions of reflective area of the element 5 in LPM
scheme have the same value as the optical scattering spot
for the optical focusing system 2 in the plane optically
conjugated with the plane containing object 3. This aim
can be achieved in LPM with LCM shown in Fig. 2, if
one of LCM control electrodes has a size no more than
the size of the scattering spot for the optical focusing
system 2. If one of LCM control electrodes has N control
electrodes that it is possible to treat fixed relatively to the
optical focusing system 2 object 3 in field of vision of the
optical focusing system 2 by the light spot with a limited
size. The larger accuracy can be achieved when control
electrodes of LCM are realized as a matrix. It is con-
nected with the fact that the scale of movement of the
light spot reflected from mirror 5 is proportional to mag-
nification of the optical focusing system 2.
For some technological tasks, for example, the treat-
ment of object with high selectivity or a treatment of only
a part of object in LPM with the scheme shown in Fig. 1
between the light splitter and light shutter placed are the
special device that can fluently attenuate light intensity.
This device is the movable optical wedge from neutral
gray glass.
In LPM with LCM that is represented in Fig. 2, the
fluent attenuation of the light intensity is achieved by the
change of control voltage peak value applied to LCM
electrodes. In this case, the selectivity of treatment is suf-
ficiently higher, because it is possible to treat the object 3
by limited light pulses with a required intensity as it will
be shown below.
In the proposed scheme of LPM with LCM for treat-
ment, recording and observation of objects by super-
radiant laser medium, it is possible to use different types
of intensity and movement sensors in order to automate
the treatment process like that in [6].
3. Experimental setup
According to the scheme shown in Fig. 2, the experimen-
tal equipment for treatment, recording and observation
of objects by superradiant laser medium was created, and
its main parameters and characteristics were measured
and investigated.
In experimental tests, LC modulators based on the
effect of electrically-controlled light reflection at the in-
terface of a glass and nematic LC were used. Here, the
geometry of NLC optical axis reorientation described in
[8] was used. Experimental samples of LC modulators
3
4
2
8
1
Fig. 1. Optical scheme of the device for treatment, observation
and recording objects by using superradiant laser medium: 1 �
superradiant laser medium, 2 � optical focusing system, 3 � ob-
ject, 4 � light split mirror, 5 � reflective mirror, 6 � screen, 7 �
system of optical wedges, 8 � modulator.
5
6
6
4
3 2
5
1
Fig. 2. Optical scheme of device for treatment, observation and
recording objects by usingsuperradiant laser medium with LCM
in treatment and observation channels: 1 � superradiant laser
medium, 2 � optical focusing system, 3 � object, 4 � LCM, 5 �
reflective mirror, 6 � screen.
P. Oleksenko et al.: Liquid crystal modulator in the channel of a laser projection microscope
311SQO, 7(3), 2004
were composed of two glass prisms with the base angle
ϕ = 63° and refractive index n = 1.8 (for λ = 510.5 nm)
and were created according to technique [9,10]. The la-
ser based on copper vapour had the following character-
istics: the light pulse duration � 30 ns, pulse repetition
frequency � 8 kHz. LCM was controlled by the sine-form
signal with the frequency of 8 kHz and amplitude of
8�80 V modulated by square pulses with the duration of
0.5 to 10 ms. Optical pulses were registered by the co-
axial photoelectric cell FEK-16 and oscilloscope I2-7
with the minimal measuring time of 0.5 ns.
4. Results and discussion
The results of our experimental investigation of LCM as
a controlling element in the resonator channel of LPM
shows that it demonstrates switching times of 0.2 and
0.4 ms (Fig. 3). Switching times were determined at the
level 0.9 at increasing and 0.1 at decreasing of electro-
optical characteristics of LCM.
The analysis of the oscillogram in Fig. 3 shows that
developed LCM can transmit pulse burst with the mini-
mal quantity of pulses equal to 7. The saturation is char-
acterized by the obvious step that guarantees the trans-
mission of powerful laser pulses with practically stable
energy. When control voltage applied to LCM is changed
from 30 up to 70 V, it demonstrates the change of trans-
mission coefficient and, as the consequence, the change
of laser pulse energy for object treatment in the range of
10 dB. The correspondent oscillograms are shown in
Fig. 4. As it can be seen in this figure, decreasing the
control voltage not only leads to decreasing the laser pulse
power but also to increasing the �switch on� time and to
insufficient decreasing the �switch off� time.
Investigations of modulation percentage M and opti-
cal losses P show the possibility of obtaining M = 99%
at P = 60%. Such high value of optical loses can be ex-
plained by the loses in polarizer (P = 50%) placed on
input plane of LCM and spurious reflection of light from
interfaces between air and glass, glass and transparent
electrode, glass and air. However, almost in all the cases
such loses do not affect efficiency and quality of object
treatment.
For investigation of LPM with LCM, technological
possibilities treatment of different samples were per-
formed.
Thin chromium films (thickness 0.1 µm) deposited on
a glass substrate and polysilicide thin films (thickness
0.3 µm) deposited on a substrate from phosphorous silicide
glass were used as laboratory samples. The size of light
spot was 1.5 by 1.5 µm. The results of sample treatment
shows that using LCM as a light shutter in LPM gives
Fig. 3. Oscillogram of an optical signal. The control voltage 50 V,
τ³ = 0.5 ms (time resolution 0.5 ms/scale)
a
c
b
Fig. 4. Oscillograms of optical signals. τ³ = 1 ms, control voltages
30 V (a), 40 V (b) and 60 V (c) (time resolution 0.5 ms/scale).
312
SQO, 7(3), 2004
P. Oleksenko et al.: Liquid crystal modulator in the channel of a laser projection microscope
possibility to remove chromium from area with repro-
ducible sizes 2 µm. The layer-by-layer controllable re-
moval of polysilicide thin film was observed when ampli-
tude of LCM control voltage was varying.
5. Conclusions
The results of our experimental investigations shows that
using LCM based on electrically controlled reflection
from the interface between isotropic dielectric and
nematic liquid crystal in treatment and observation chan-
nels of LPM, which simultaneously acts as a modulator,
attenuator and light beam splitter can sufficiently im-
prove characteristics of LPM and enlarge its functional
possibilities.
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