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Processes and micro technologies for generation of “master masks” for incremental disks divisor and vernier of
position and angular photoelectric incremental transducers
The Romanian Review Precision Mechanics, Optics & Mecatronics, 2007 (17), No. 32 957
PROCESSES AND MICRO TECHNOLOGIES FOR
GENERATION OF “MASTER MASKS” FOR INCREMENTAL
DISKS DIVISOR AND VERNIER OF POSITION AND
ANGULAR PHOTOELECTRIC INCREMENTAL
TRANSDUCERS
Ph.D. Gheorghe I. Gheorghe – Managing Director
National Institute of Research and Development in Precision Mechanics – Bucharest
Ph. D. Octavian Dontu, UPB, Mechanical Engineering and Mecatronics Faculty – Bucharest
Abstract – Precision of the transducer is directly dictated by precision of disks division, by quality of opaque-transparent contrast, by rectilearity of transparent-opaque demarcation line as well as geometry of transparent-opaque areas. Realization of incremental disks is made by photographic technique. One of the methods involves existence of an original mask that multiplies by transferring image from a transparent support on which is laid-down a metal and a photosensitive layer; as a result of corrosion, the part from metallic layer unprotected is eliminated, resulting desired configuration.
Taking in consideration very small dimensions of plotting and high density, technique method for realizing these disks is litophotographic, which allows reaching submicronic dimensions. As regards relative positioning precisions of routes, in case of settlement in X, Y coordinates (frequent in microelectronics), technique of producing masks beneficiates the following
advantage: execution of a mask less pretentious to hundreds times higher scale, which by successive reductions reaches high precisions. Keywords – micro technologies, master masks
Introduction
Fundamental Considerations
Is presented, designed and realized the
incremental angular position transducer (fig. 1).
Precision of the transducer is directly
dictated by precision of disks division, by quality of
opaque-transparent contrast, by rectilearity of
transparent-opaque demarcation line as well as
geometry of transparent-opaque areas.
Realization of incremental disks is made by
photographic technique. One of the methods
involves existence of an original mask that
multip lies by transferring image from a transparent
support on which is laid-down a metal and a
photosensitive layer; as a result of corrosion, the part
from metallic layer unprotected is eliminated,
resulting desired configuration.
Fig. 1
Taking in consideration very small dimensions of plotting and high density, technique
Processes and micro technologies for generation of “master masks” for incremental disks divisor and vernier of
position and angular photoelectric incremental transducers
The Romanian Review Precision Mechanics, Optics & Mecatronics, 2007 (17), No. 32 958
method for realizing these disks is litophotographic,
which allows reaching submicronic dimensions.
As regards relative positioning precisions of
routes, in case of settlement in X, Y coordinates
(frequent in microelectronics), technique of
producing masks beneficiates the following
advantage: execution of a mask less pretentious to
hundreds times higher scale, which by successive
reductions reaches high precisions.
In case of radial settlement of routes at
masks for coder d isks, where appear the problem of
angular position, technique of reducing masks
doesn’t has the effect of increasing precision, so the
quality of method for generating mask is transmitted
directly to the product.
Execution of mask at a higher scale could
bring facilities in execution, taking into account
increase of routes dimensions, but it could have
imposed the use in mult iplying flow of an
intermediary mask obtained on a reduction bank.
To eliminate this technological stage (which
besides supplementary work volume brings a lack o
quality) was used the idea of realizing masks at 1:1
scale.
Work principle for mean of generating
routes is impressing by light fascicle of photo
sensitive emulsion, from a system with laser ray.
Taking into account that in technology of
transferring image mask-sublayer, photo emulsion
enter in direct contact with photoresist and taking in
consideration weak mechanical resistance of
emulsion, for increasing work life, the work masks
has to be copies on chrome of the originals.
This involves that original masks must be
positive of disks images.
In conclusion, masks are obtained on photo
emulsion, on optical glass support, at 1:1 scale,
carrying the positive of disks configurations (with
some auxiliary traces imposed on measurement and
multip lying technology).
“Etalon mask” configuration
Aligning reticules and technological routes
At the base of establishing mask routes are
execution drawings of incremental disks divisor and
vernier.
Taking into account necessity of measuring
marks, there is the problem of materializing
incremental d isks and of tracing orig in ( = 0 ).
That is way on each mask appears a
reticular central cross and two pairs of indexes
adjusted at 900.
Dimensions of these routes are imposed by
technical characteristics of observation methods and
measuring of the masks. Also, is introduced a
measuring tracks (with 140 mm diameter) on which
is a route at each 10 increments.
For centering operations, for reproducing
and debiting disks sublayer, is necessary existence
on the mask of some concentric circles at specific
dimensions.
As regards the geometry of routes from
measuring tracks, there are two variants for
realization, according to figure 2 and figure 3.
Fig. 2 Fig. 3
Technological quotation
Taking into account technique for
generating masks in polar coordinates for each route
must be defined the following elements:
Medium ray; route thickness;
Angular position of radial symmetry
axe of the route;
Maximum and minimum ray ;
Route thicknesses corresponding to
Rmin and Rmax; respectively all there
elements disposed radially (fig. 4).
Processes and micro technologies for generation of “master masks” for incremental disks divisor and vernier of
position and angular photoelectric incremental transducers
The Romanian Review Precision Mechanics, Optics & Mecatronics, 2007 (17), No. 32 959
Fig. 4
According to these requests were quoted
sketches from figures 5, 6, 7, 8 and values are given
tabular for each mask, according to tables 1, 2, 3, 4.
Fig. 5
Fig. 6
Fig. 7
Processes and micro technologies for generation of “master masks” for incremental disks divisor and vernier of
position and angular photoelectric incremental transducers
The Romanian Review Precision Mechanics, Optics & Mecatronics, 2007 (17), No. 32 960
Fig. 8
Tabel nr. 1.
i 2Rmin i 2Rmaxi i 2xi 2yi i
1 30 34 / 2 0 10’48” 0,0471 0,0534 0
2 35 39 2 0 43’12” 0,2199 0,2450 3 / 4
3 35 39 0 21’36” 0,1099 0,1225 4 + / 4
4 35 39 0 21’36” 0,1099 0,1225 6 + / 4
5 35 39 0 21’36” 0,1099 0,1225 9 + / 4
6 35 39 0 21’36” 0,1099 0,1225 13 + / 4
7 35 39 3 1 4’48” 0,3298 0,3675 16 + / 4
Tabel nr. 2.
I 2Rmin i 2Rmaxi i 2xi 2yi i
1 30 34 / 2 0 10’48” 0,0471 0,0534 0
2 35 39 3 1 04’48” 0,3298 0,3675 49 +3 / 4
3 35 39 0 21’36” 0,1099 0,1225 52 + 3 / 4
4 35 39 0 21’36” 0,1099 0,1225 56 + 3 / 4
5 35 39 0 21’36” 0,1099 0,1225 59 + 3 / 4
6 35 39 0 21’36” 0,1099 0,1225 61 + 3 / 4
7 35 39 2 0 43’12” 0,2199 0,2450 65 + / 4
Tabel nr. 3
Processes and micro technologies for generation of “master masks” for incremental disks divisor and vernier of
position and angular photoelectric incremental transducers
The Romanian Review Precision Mechanics, Optics & Mecatronics, 2007 (17), No. 32 961
I 2Rmin i 2Rmaxi i 2xi 2yi i
1 30 34 / 2 0 05’24” 0,02356 0,0267 0
2 35 39 0 10’48” 0,0549 0.06126 3 / 4 8’6”
3 35 39 0 10’48” 0,0549 0.06126 2 +3 /4 29’42”
4 35 39 0 10’48” 0,0549 0.06126 5 +3 /4 1 2’6”
5 35 39 2 0 21’36” 0,109956 0,1225 9 + / 4 1 45’18”
6 35 39 0 10’48” 0,0549 0.06126 11 + 3 / 4
7 35 39 2 0 21’36” 0,1099 0,1225 14 + / 4
8 35 39 0 10’48” 0,0549 0.06126 18 + 3 / 4
9 35 39 3 0 32’24” 0,1649 0,06126 25 + 3 / 4
10 35 39 0 10’48” 0,0549 0.06126 28 + 3 / 4
11 35 39 2 0 21’36” 0,1099 0,1225 33 + / 4
Tabel 4
I 2Rmin i 2Rmaxi I 2xi 2yi i
1 30 34 / 2 0 05’24” 0,02356 0,0267 0
2 35 39 2 0 21’36” 0,1099 0,1225 102 + 3 / 4
3 35 39 0 10’48” 0,0549 0.06126 107 + / 4
4 35 39 3 0 32’24” 0,1649 0,06126 110 + 3 / 4
5 35 39 0 10’48” 0,0549 0.06126 117 + / 4
6 35 39 2 0 21’36” 0,1099 0,1225 121 + 3 / 4
7 35 39 0 10’48” 0,0549 0.06126 124 + / 4
8 35 39 2 0 21’36” 0,1099 0,1225 126 + 3 / 4
9 35 39 0 10’48” 0,0549 0.06126 130 + 2 / 4
10 35 39 0 10’48” 0,0549 0.06126 133 + / 4
11 35 39 0 10’48” 0,0549 0.06126 135 + / 4
Technological flow
Due to the special influence of
environmental conditions on dimensional precision
and masks quality, the entire process of realizing
originals is made in the laboratory, in climat ic
conditions strictly adjusted at the following
parameters:
- Temperature: 20 C 2 C;
- Humidity: 45% 5%;
- High degree of dust separation.
Besides these general air-condit ioning
characteristics, there are also used local temperature
adjustments on workstations in chemical p rocessing.
Block scheme of technological flow is
given by figure 9, being evidenced large groups of
operations and base methods of realization.
Programming
The routine contains commands and
informat ion given to the system regarding
dimensions of routes, positioning, factors of tracing
cinematic and succession of operations.
All these commands are elaborated on idea
of realization high precision of circu lar d ivision and
idea of min imizing method errors (errors cumulated
resulted from a round calculation by repeated
summarizations and of a step, errors given by limits
imposed by the computer to significant dig its).
The minim increment of angular command
in polar coordinates is 0.25”. The routine is
expressed by a computer language computer own,
and the diagram that shows how is made is given by
the figures 10 and 11.
Processes and micro technologies for generation of “master masks” for incremental disks divisor and vernier of
position and angular photoelectric incremental transducers
The Romanian Review Precision Mechanics, Optics & Mecatronics, 2007 (17), No. 32 962
ADJUSTEMENT OF MASKS
DIMENSIONS
ADJUSTEMENT OF TRACING ALGORITM
PROGRAMMING
GENERATING PUNCHED
BAND
TRACING FOR CHECKING ROUTINE
STANDARD PROCESSING
MASKS INSPECTION
ROUTINE CORRECTIONS
TRACING SAMPLES TECHNOLOGICAL SAMPLES
PROCESSING IN CORRECTED CONDITIIONS
MASKS INSPECTION
MEASUREMENT
CORRESPOND
DATA INTERPRETATION
STOP
1
2
3
4
5
6
7
8
9
10
11
12
13
EXPOSURE CORRECTION R
b
[OKITYPER 5800]
[SISTEM PMPG R1010]
MICROSCOP MESMI 75
MICROSCOP ASAHI
MICROSCOP PERAVAL
PLATE DIVIZOR ZEISS OPTON RT 05
NO
YES
NO
YES
SISTEM PMPG
RD 0101
Fig. 9
START
CORRESPOND
Processes and micro technologies for generation of “master masks” for incremental disks divisor and vernier of
position and angular photoelectric incremental transducers
The Romanian Review Precision Mechanics, Optics & Mecatronics, 2007 (17), No. 32 963
START
CROSS TRACING DOUBLE RETICULAR
TRACING CIRCLE DE-MARCATION, INTERIOR
TRACING CIRCLE INTERIOR CENTERING
TRACING INDEXES
OF 0 AND 90
SUBROUTINE EXECUTION - 100 TIMES (200 TIMES)
TRACING TRACK "0"
TRACING
INTERMEGIARY CIRCLE
TRACING CIRCLE EXTERIOR
DEMARCATION
TRACING CIRCLE INTERIOR CENTERING
STOP
SUBROUTINE DIVISION MEASU-REMENT TRACK
SUBROUTINE EXECUTION - 8 TIMES (28 TIMES)
SUBROUTINE DIVISION
READING TRACK
TRACING INDEXES OF
0 AND 90
TRACING CIRCLE INTERIOR CENTERING
TRACING CIRCLE DE-MARCATION, INTERIOR
CROSS TRACING DOUBLE RETICULAR
START
TRACING TRACK OF "0"
TRACING
INTERMEGIARY CIRCLE
TRACING CIRCLE EXTERIOR
DEMARCATION
TRACING CIRCLE INTERIOR CENTERING
STOP
Fig. 10 Fig. 11
Tracing
The principle of system tracing [PMG R
0101 - pattern generator] is as follows: a laser spot
dimensionally controlled, whose symmetry axis is
rigorous centered, focalized in photo emulsion
plane, is moved on a direction impressing sensitive
plaque, which fixed on a gyrating table is angularly
moving (part icular case of tracing in polar
coordinates).
Carrying sublayer of photosensitive
material is fixed in a vacuuming device.
Focalizat ion is made in two stages:
Manual focalization for bringing with
Processes and micro technologies for generation of “master masks” for incremental disks divisor and vernier of
position and angular photoelectric incremental transducers
The Romanian Review Precision Mechanics, Optics & Mecatronics, 2007 (17), No. 32 964
approximation on adjusting range ( 0,5 m);
Automate focalizat ion, maintained during
tracing for deviations from planarity take-up
and perpendicularity at optical axis.
On the entire flow, there are used as
photosensitive materials AGFA films on polyester
support OP 81 GEVALITH for routine samples,
aligning, centering and AGFA films on glass support
HOLOTEST 10 E 56 for samples of exposing route
samples and final masks.
In term of sensitivity, spectral sensitivity,
exposing lamp characteristics, dimensional
corrections proposed for routes in optical route are
interposed color filters and transmission filters.
Values for wave lengths and transmission
coefficients have a theoretical base, being then
experimentally adjusted for obtaining desired results
on both qualities of film.
Chemical microtechnologies for master masks
processing
Together with exposing and sensitivity of
photographic plaque, chemical processing is
considered as being the third critical factor in
obtaining images with high resolution. Standard
technique for processing exposed masks (negative
process) presents a series of variables, with more o r
less stages, in term of photosensitive materials. But a
complete process will necessary involve the
following stages:
1 – alkaline treatment for deantiholoing (variab le
only for antiholo layer plaques);
2 – washing with flowing water (also for plaques
with antiholo treatment);
3 – developing with continuous swirling;
4 – washing in flowing water;
5 – fixing in fixing solution with frequent swirling;
6 – washing in flowing water;
7 – drying.
If the alkaline treatment applied in case of
plaques endowed on the back side with antiholo
layer doesn’t represent a special problem, chemical
reactions from developing operation are significant
for the process.
A typical developing solution will contain:
1 • solvent (which is water); 2 • reducing agent; 3 •
activator; 4 • maintaining agent; 5 • modeler.
Basic reaction is reducing granules of silver
halide exposed to metallic silver with help of
reduction agent, which is a reactive from phenols
series (is exemplified by hydroquinone) and in
alkaline solution is in a ionized state and in a
relatively high concentration (fig. 12).
+2H++2Ag
++2OH
-→2Ag
0+ +2H2O
OH
OH
O-
O
O
O
Fig. 12
This reaction begins in latent status image
fall into silver halide granules exposed and continue
until developing is stopped.
Metallic silver wires resulted produce
optical density of image resulted in emulsion. As
typical moderator is used potassium bromide which
delays developing at unexposed granules level,
forming some kind of area electrostatic charged
around them, which act as a barrier to reducing
agent. Maintaining agent is alkaline antioxidant type
sodium sulphite that slows oxidation of active
reducing agent and is situated in developing solution
in contact with atmospheric oxygen.
Because developing reaction is produced
especially in emulsion with exposed granules, a
slight agitation is indicated to allow fresh developing
agent to dispel inside.
Developing reaction can be stopped in the
following phase of washing in flowing water and
more rapid ly, although not indicated (because
produces malformations at emulsion level) in
slightly acid solutions.
Developing stage is especially critical and
necessitates a rigorous control of the process.
Selectiv ity of the silver halide granules towards
reducing agent from developer is limited to a short
period of time, if the process continues, reduction
reaction will continue as well with a decreasing
speed until reducing the entire quantity of silver
halide, exposed or unexposed to metallic silver.
Practical experience demonstrates that
activity degree of developing, time, temperature and
agitation state of solution is in connection with
quantity of silver developed. Rigorous control of
these factors leads to endowment of development
baths from processing installations, extra towards
other baths (which have submicronic filtering and
agitation) with precision thermometers of 0,2 C,
chronometers and pH indicators for activ ity level o f
developer. In fixing stage, takes place removing
silver halide remained in unexposed areas.
Reaction takes place between salt cake or
ammonia sulphate, in water solution of fixing agent
in ionized state and silver halide, which forming in
this way soluble complexes, can be removed by
washing: 32)302(SAG
2302S AgX şi
X52)302(SAG (1)
Traces of disulphide in emulsion, not
Processes and micro technologies for generation of “master masks” for incremental disks divisor and vernier of
position and angular photoelectric incremental transducers
The Romanian Review Precision Mechanics, Optics & Mecatronics, 2007 (17), No. 32 965
removed by washing, can later produce defects of
image.
The last stage of masks drying and which is
also a part of processing technology, although
appears unimportant, was hardly studied.
Thereby is very important that no mater
which method of drying is used, washing that
precedes it to be made in clean water, so after drying
to not appear on the mask from previous operations
traces of chemicals, reaction products, colorants or
other types of materials.
There are used for basic techniques for
drying masks, each with a higher or smaller
extension:
Drying by evaporating water: the main
advantages are: long period of t ime when drying
takes place at room temperature or danger for
deforming image when drying temperature
exceeds a certain value. Also, the system
presents a high degree of danger for mask
contamination.
Removing through physical methods of the
water: is realized by forced drying with air jet o r
centrifuging. By air jet, dry ing can result in
photo masks with residuum traces in marginal
areas, where water leaved the plaque,
centrifuging method representing this fault, but
in general is accessible in a limited area of the
mask.
Dilution with rapid evaporation of the solvent:
is also method applied in practice, uses
methanol (very toxic) or ethanol, polar solvents
slightly volatile and with water forms mixtures
miscible in any proportion.
The process includes three successive baths
where the solvent grows from 25% to 100% in the
last bath, allowing that water extraction from
gelatine to be made with a moderate speed without
degraded it (blue veil phenomena).
Movement with solvent with high drying speed;
drying involves overlapping of two phenomena:
Replacing water from dried surface with a
liquid with superficial low vo ltage;
Movement of water droppings at the surface
(water having lower density) and gathering
them in a system with separator, liquid being
recircu lated.
In studies also appear a variant of this
system called “drying with spaces within phases”.
The two phases that participate to water
removal can be for example tricloretine and a
mixture of alcohol with Freon.
The process takes place as shown in the
figure below (fig. 13), where there are displayed the
six stages if the process that takes place:
The drop of water from the surface of the
plaque that was immersed in solvents mixtu res;
A part of alcohol is extracted from the drop of
water;
Following modification of the density as well as
superficial voltage towards plaque, the drop is
removed from the plaque and is lifted;
At the surface is formed a d istinct phase from
water and alcohol;
Plaque extracted from solvent, which has on the
surface a layer absorbed by the alcohol, Freon
which rep laced water, this is found on solvent
surface in equilibrium with a layer from solvent
vapors;
By rap id evaporation at air, this layer is
removed.
Fig. 13
In figure 14, is also reproduced a system
that realize quick d rying of photo plaques by this
method.
The system is applicable at realizat ion in
large series of the mark.
Even in best systems of exposing and
processing of the masks, the result cannot be
represented as very precise areas of passing from
opaque to transparent, as a result of optical exposure
systems imperfect ions, as well as limitations of
processing solutions selectivity.
Wa
ter
se
pa
rato
r
water
Processing compartment
D
eca
nte
r re
se
rvo
ir
Wa
ter
at
dra
inin
g
Freon – alcohol vapors layer
water
Freon – alcohol
distillate
Fig. 14
Processes and micro technologies for generation of “master masks” for incremental disks divisor and vernier of
position and angular photoelectric incremental transducers
The Romanian Review Precision Mechanics, Optics & Mecatronics, 2007 (17), No. 32 966
In figure 15, can be seen the influence of
exposure and developing on emulsion thickness. Can
be seen at the final phase exposed and developed (d)
how as a result of the process appeared thickness
differences of opaque areas and there are unwanted
especially in t ransfer through contact method.
Emulsion transparent substrate glass
Effect of exposure and developing on
glass mask emulsion thickness
2,0
3
6,0
0 μ
m
C A
4,0
0 μ
m Emulsion(opaque)
4,0
0 μ
m
2,0
3 μ
m Emulsion (transparent)
B D
• Unexposed and undeveloped
• Developed and unexposed areas
• Unexposed and undeveloped • Exposed and developed
Emulsion
Fig. 15
In figure 16, is reproduced the curve of
image profile of a HRP-KODAC plaque – processed
by negative process where is observed behavior of
emulsion towards light energy absorbed at exposure
and who made that line of 100 m (2,54 inch) to
have the aspect from the figure.
Fig. 16
Processes and micro technologies for generation of “master masks” for incremental disks divisor and vernier of
position and angular photoelectric incremental transducers
The Romanian Review Precision Mechanics, Optics & Mecatronics, 2007 (17), No. 32 967
Moreover, experimentation showed that as
line narrows, is less dense, so in the same image of
the mask we have wider lines with higher density
and narrow and less dense lines. If density control of
the mask were made on wider areas, we must have a
higher density here to assure convenient values at
thicker lines (narrower surfaces). But the differences
in density between wider and narrower lines depend
on too many factors, first of all on developing lens.
Conditions for practical realizing of processing
Realizing masks processing (AGFA -
GEVERT) was made in following stages:
Developing: 4 minutes at 20 C 0,1 C in
developer G 2820 (a part concentrated + 2 parts
distilled water);
Washing in flowing water at 20 C for 2
minutes;
Fixing in fixative G 333 c (1 part
concentrate + 4 parts distilled water at 20 C 1 C,
for 2 minutes);
Washing in flowing water for 10 minutes;
Drying no. 1 in 25% ethanol + 75%
distilled water for 30 seconds;
Drying no. 2 in 50% ethanol + 50%
distilled water for 30 seconds;
Drying no. 3 in 100% ethanol (absolute
ethylic alcohol) for 45 seconds;
Dry ing at air in niche with laminar flow
for 10 seconds;
Measuring masks is possible after
approximately 1 hour from processing when they
reached constant temperature from measuring
chamber.
Control of tracing and processing quality
Taking into consideration functionality of
divided lines in incremental transducer and taking
into account traces configurations, control
technology followed determining parameters:
Contrast;
Quality of demarcation opaque-transparent line;
Observation of imperfections of traces
continuity.
Microtechnologies for obtaining masks
being closed loop type, all informat ion given by
inspecting masks lead to applying corrections in
various phases of realizations.
Appreciations on contrast give informat ion
on processing exposing parameters, being in this
way corrected: power of exposing laser, filters
values, tracing speed, adjustment of laser light flow
in transitory regime (accelerations, decelerations).
The quality of severance line between transparency
zones and opacity zones leads to controls and
alignments of optical components placed in the
luminosity way of exposition and on the adjustment
of laser light spot focusing.
The comparison of geometrical routes with
widths that are propose in theoretical way, determine
the effectuation of direct adjustment on equipment,
and indirect by interposing of filters on the optical
path of the routes that represents deviance. Routes
break are determined by additions from the medium
and by emulsion imperfect ions, leads to resume of
operations with warning as much as is possible,
about the factors that are responsible for these
disorders.
The necessary data for inspection of the
masks are determinate using laboratory equipment,
follow as:
Stand for measuring lengths with laser
interferometer with microscopic
visualizat ion [MESMIT 5];
Stand for measuring angular
displacements on divisor tables
[ZEISS-OPTON-RT 05] with
microscope [X-Y ASAHI];
- interfential microscope [PERAVAL]
Measurement of master mask
Measurement of the mask refers to
determination of angular precision for traces
positioning disposed on incremental track. This
characteristic of divisor disk (transmitted by the
original mask) gives the quality of angular
incremental transducer.
Measurement of the mask is made on stand
[PMPG R 0101] with the following principles:
a rotary movement is imposed around
their center;
on one side and the other of the mask
there are illuminating laser system,
respectively reception system of a
photoelectric microscope;
each black white border distinguished
by the microscope is transmitted to
measurement system.
Measurement system is dimensioned for
high overall size disks, so it was necessary to bring
certain constructive modificat ions. Besides these
modifications, is necessary that in measurement, to
apply an indirect technique that consist in
measurement of angular positioning error of some
technological routes generated in this purpose. So,
for each tenth division of increments track (φ 40)
correspond a division of measurement track (φ 70),
the two divisions being rigorously on the same ray.
So position deviation of two divisions on
measurement track will be error between division
Processes and micro technologies for generation of “master masks” for incremental disks divisor and vernier of
position and angular photoelectric incremental transducers
The Romanian Review Precision Mechanics, Optics & Mecatronics, 2007 (17), No. 32 968
“n” and “n + 10” on the incremental t rack:
precision of measurement stand: 0,5 sec.;
measurement orig in: first indexed trace;
measurement direct ion: trigonometric;
Errors diagonals represent angular
deviations between symmetry axes of traces.
Figurative data contain, beside mask deviations,
errors of measurement which cannot be eliminated
taking into account that mask is drawing in
prescribed tolerance.
Verniers errors are:
for vernier disk, for 1000 divisions/
circumference;
+ 1 second arc; - 1,5 second arc;
for vern ier d isk, for 2000 d ivisions/ circumference:
+ 0,5 seconds arc; - 1,5 seconds arc.
Errors of incremental d ivisor disks (fig. 17 and
18).
Fig. 17
Fig. 18
for incremental div isor disk with 1000
divisions/ circumference: + 1,5 seconds arc; -
2,5 seconds arc;
for incremental div isor disk with 2000
divisions/ circumference: + 1,5 seconds arc; -
1,5 seconds arc.
References
Gheorghe, I. Gh: Instruments Engineering –
Photoelectric incremental systems and
transducers of displacement and position used in
precision mechanics, mecatronics and robotics;
Cefin; ISBN 973-99591-0-5/ISBN 973-99591-1-3; 1999;