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5 Laser Specklometer, Speckle-Optical Diagnostics and Laser …
A. The position of the legs relative to the head can be modified due to the height and
the angle.
In the process of operation, the laser radiation is brought into the light guide 1,
which is established in the conjunction block (head), passes through it, then moves
aside by the prism 13 and illuminates the surface under study A.
Partially reflected, scattered light passes through the prism 13 backward, comes
into the second light guide 1 and goes through it to the tip 2, fixed on the PMT unit.
Introduction of the beam to transmitting light guide is conducted in the block of
conjunction of laser with the light guide. It consists of the body 1 (Fig. 5.9), in the
borings of which the eccentrics 2 and the barrel 3 are placed. One of the tips 4 of the
block of the light guides is fixed in the barrel. The eccentric axes 5 with the bearings
6 are fixed along the eccentric axis 2. The frame 8 with the objective 9 is pressed
with the spring 7 to bearings. The frame 8 is placed in the gap between the body 1
and tablet 10. The nut 12 is put in the gap between the body 1 and cover 11. The nut
is connected to the bushing.
During adjustment, the beam from prism goes along the objective axis and shifts
perpendicular to its axis because of transverse shift of the frame 8 with the objective 9
during rotation of the eccentrics 2 and the eccentric axis 5. At that using the eccentrics
2 (their eccentricity is 500 μm), preliminary tuning was performed, and using the
eccentric axes 5 (their eccentricity is 50 μm) accurate shift of the laser beam with the
axis of the light guide was made. To join the face of the light guide with the focus of
the objective 9 and, thus, to obtain maximal energy input of the laser radiation into
the light guide, axial shift of the barrel 3 is conducted through rotation of the nut 12.
3. The electric part of the laser specklometer.
The electric part of the laser specklometer contains a unit of preliminary
processing and an indicator of power of the laser radiation. The unit of preliminary
processing consists of a preliminary PMT signal intensifier: a programmed intensifier; a low-frequency filter 1; a detector and a low-frequency filter 2; connection
with an electronic processing unit and a personal computer; a high-voltage power
supply of PMT; and a power supply.
3.1. The construction of preliminary processing unit (PPU).
The PPU units are assembled on printed-circuit boards, mounted into the
body and joined through wiring.
The PPU is situated on a plate base of the optical-mechanical part of the
specklometer.
On the PPU body, there are fixed two connectors for connection of the electrical processing block and the PC; contact plug for PMT connection; and
a contact plug for connection of the power voltage. The PPU construction
provides access to adjustment and replacement of separate units, possibility
to control their parameters during repair.
3.2. Characteristics of the PPU purpose:
(a) The preliminary intensifier provides PMT output matching.
5 Laser Specklometer, Speckle-Optical Diagnostics and Laser …
A. The position of the legs relative to the head can be modified due to the height and
the angle.
In the process of operation, the laser radiation is brought into the light guide 1,
which is established in the conjunction block (head), passes through it, then moves
aside by the prism 13 and illuminates the surface under study A.
Partially reflected, scattered light passes through the prism 13 backward, comes
into the second light guide 1 and goes through it to the tip 2, fixed on the PMT unit.
Introduction of the beam to transmitting light guide is conducted in the block of
conjunction of laser with the light guide. It consists of the body 1 (Fig. 5.9), in the
borings of which the eccentrics 2 and the barrel 3 are placed. One of the tips 4 of the
block of the light guides is fixed in the barrel. The eccentric axes 5 with the bearings
6 are fixed along the eccentric axis 2. The frame 8 with the objective 9 is pressed
with the spring 7 to bearings. The frame 8 is placed in the gap between the body 1
and tablet 10. The nut 12 is put in the gap between the body 1 and cover 11. The nut
is connected to the bushing.
During adjustment, the beam from prism goes along the objective axis and shifts
perpendicular to its axis because of transverse shift of the frame 8 with the objective 9
during rotation of the eccentrics 2 and the eccentric axis 5. At that using the eccentrics
2 (their eccentricity is 500 μm), preliminary tuning was performed, and using the
eccentric axes 5 (their eccentricity is 50 μm) accurate shift of the laser beam with the
axis of the light guide was made. To join the face of the light guide with the focus of
the objective 9 and, thus, to obtain maximal energy input of the laser radiation into
the light guide, axial shift of the barrel 3 is conducted through rotation of the nut 12.
3. The electric part of the laser specklometer.
The electric part of the laser specklometer contains a unit of preliminary
processing and an indicator of power of the laser radiation. The unit of preliminary
processing consists of a preliminary PMT signal intensifier: a programmed intensifier; a low-frequency filter 1; a detector and a low-frequency filter 2; connection
with an electronic processing unit and a personal computer; a high-voltage power
supply of PMT; and a power supply.
3.1. The construction of preliminary processing unit (PPU).
The PPU units are assembled on printed-circuit boards, mounted into the
body and joined through wiring.
The PPU is situated on a plate base of the optical-mechanical part of the
specklometer.
On the PPU body, there are fixed two connectors for connection of the electrical processing block and the PC; contact plug for PMT connection; and
a contact plug for connection of the power voltage. The PPU construction
provides access to adjustment and replacement of separate units, possibility
to control their parameters during repair.
3.2. Characteristics of the PPU purpose:
(a) The preliminary intensifier provides PMT output matching.