OPTIMIZATION OF THE LASER

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04770A002600020023-8
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 3
• Document Creation Date: December 28, 2016
• Document Release Date: December 9, 2002
• Sequence Number: 23
• Publication Date: June 1, 1964
• Content Type: PERRPT

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PAR. 217
1 June 64
SUBJECT-. Optimization of the Laser
TASK/PROBLEM
1, Explore the production of 0.5 micron (blue-green) laser radiation
by harmonic doubling in KDP and AOD crystals.
2. Work on this project was authorized 2 March and study began
in"early April. A laboratory setup has been made to generate and detect the
5300A second harmonic component from a neodymium laser.
3. The set-up consists of a 12-inch neodymium laser mounted
on one end of a heavy duty optical bench and enclosed in a "light-
tight"' cavity. At the output end of the cavity is a one-inch aperture
covered with a visibly opaque, infrared transmitting filter f lass. This
filter material, 2540, transmits about 8(% of the fundamental
1.06 micron radii utside of this light-tight cavity, but also
mounted on the optical bench, is the one-inch square, 5mm thick K.D.P.
crystal held in a micrometer controlled precision gimbal mount. A piece
of 12043 heat absorbing glass is placed in the beam between the
crystal and the green light detector to filter out the residual 1.06
micron radiation. The detecting element currently being used is a 929
photocell with an integrating circuit which provides a D.C. voltage
proportional to the incident 5300A radiation.
!t. The initial results from this study indicated that our
K.D.P. crystals were not optimally oriented. Further, measurements
indicate that the angle between the surface normal and the optical axis
of the crystal should be approximately 46?, rather than the present
41%
5, Measurements were also made to determine the 5300A output
as a function of the crystal rotation. The results, which we believe
to be accurate to 10% show this output decreasing to 50% of peak in
1/6? rotation with a further decrease to 10% of peak in less than
1/2* rotation as shown in Figure 1. This agrees well with available
published data.
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 Approved For Release 2003/01/x: CIA-RDP78BO477OA002600020023-8
Graph of relative output vs crystal orientation
in harmonic doubling of laser radiation
,2ct'.RE?
160
.90
. z-o
.l0
5
15 z0 Z5 30 3S
.ANGLE. IN MINUTE-5
40
45
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PAR 217
1 June 64
6. 0urrentl we are awaiting three more K.D.P. crystals from
with the optical axis oriented at 1t6 to the
surface normal. Two of these crystals are 1.5 inches square and
5mm thick, the third is one inch square and one cm thick.
7. Also during the quarter, a visit was made to
to discuss the plasma pinch experiments of
I uin one of which the discharge acted as a laser pump.
This approach is interesting as it provides high-intensity pumping
in a very narrow spectral wavelength region as opposed to the more
conventional black-body radiation pumping with flash tubes. The pinch
pump has the advantage of reducing radiative heating of the laser rod.
It is hoped that this technique in combination with harmonic doubling
can produce 5300A radiation at high repetition rate.
8. During the next quarter effort will be aimed at increas-
ing the intensity of the second harmonic output. Techniques such as
optimizing the'incident 1.06 micron beam pattern, focusing the beam
on'the crystal, Q-switching: using two or more crystals in series,
etc. will be tried. The results of this effort hopefully will be
quantitative data on both output intensity and efficiency.
9. In addition, to this, effort will also be directed toward de-
veloping the theta or plasma pinch technique as an optical pump for
high repetition rate laser operation. Discussions with at
have indicated feasibility ..n this
area, and a as outlined several of the basic operational requirements.
We have a power supply which will be tried as the driving source.
We also have several argon-filled pinch tubes and are in the process
of assembling the experimental equipment.
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