 Thu May 23 23:27:38 2019, Koji, Optics, Characterization, IGHQEX3000 high power test 
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LaserComponents IGHQEX3000 (Cage B2: Serial# B1-23) was exposed to the beam with the optical power from 1.6mW to 332mW.
After each illumination, the dark current and the dark noise level were measured. Also the photo image of the PD surface was taken each time.
- No significant change of the dark current after each illumination. |
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Mon Jul 1 12:38:49 2019, Koji, Optics, Characterization, A and M prisms perpendicularity measurement 6x
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[Stephen, Koji]
The perpendicularity of some of the A and M prisms were tested.
Results |
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Mon Jul 1 12:49:42 2019, Koji, Optics, Characterization, Scattering measurement of A and C mirrors
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| Liyuan's scattering measurement for the A and C mirrors. |
 Thu Aug 22 12:35:53 2019, Stephen, Optics, Characterization, Wedging of the debonded PZTs 2019 August
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Wedge and thickness measurements of PZTs 12 and 13 took place after debonding and cleaning - results are shown in the first image (handwritten post-it
format).
These thickness measurements seem to have come back thinner than previous measurements. It is possible that I have removed some PZT material |
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Fri Aug 23 11:11:44 2019, shruti, Optics, Characterization, Finding the curvature bottom
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I attempted to fit the data taken by Koji of the beam spot precession at the CCD in order to find the location of the curvature bottom in terms
of its distance (d) and angle () from the centre of the mirror. This was done using
the method described in a previous similar measurement and Section 2.1.3 of |
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Thu Aug 29 11:51:49 2019, shruti, Optics, Characterization, Wedging of the debonded PZTs - Calculation
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Using the measurements of PZTs 12,13 taken by Stephen, I estimated the wedging angle and orientation following Section 2.3.1 of T1500060. The results
can be found in Attachment1 and is summarised as follows.
For PZT 12, PZT 13 respectively: |
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Thu Oct 8 19:55:22 2020, Koji, General, Characterization, Power Measurement of Mephisto 800NE 1166A
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The output of Mephisto 800NE (former TNI laser) was measured.
The output power was measured with Thorlabs sensors (S401C and S144C). The reference output record on the chassis says the output was 837mW at 2.1A
injection. |
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Sat Nov 21 13:58:30 2020, Koji, Electronics, Characterization, Dark Current Measurement for InGaAs QPDs
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Dark current measurement for InGaAs QPDs (OSI FCI-InGaAs-Q3000) has been done using Keithley 2450 and Frank's diode test kit. Frank's setup uses
various custom instruments which are no longer exist, therefore the kit was used only for switching between the segments.
The diodes were serialized as 81, 82, 83, 84, continuing the numbering for the OMC QPDs. The numbers are engraved at the side and the back of |
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Sun Nov 22 13:49:12 2020, Koji, Electronics, Characterization, Impedance Measurement for InGaAs QPDs
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To know any anomaly to the junction capacitance of the QPD segments, the RF impedances were tested with a hand-made impedance measurement.
All segments look almost identical in terms of capacitance.
Measurement setup: |
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Mon Nov 23 23:17:19 2020, Koji, Electronics, Characterization, The dark noise of the Q3000 QPDs
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The dark noise levels of the four Q3000 QPDs were measured with FEMTO DLPCA200 low noise transimpedance amp.
The measurement has been done in the audio frequency band. The amp gain was 10^7 V/A. The reverse bias was set to be 5V and the DC output of
the amplifier was ~40mV which corresponds to the dark current of 4nA. It is consistent with the dark current measurement. |
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Tue Nov 24 10:45:07 2020, gautam, Electronics, Characterization, The dark noise of the Q3000 QPDs
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I see that these measurements are done out to 100 kHz - I guess there is no reason to suspect anything at 55 MHz which is where this QPD will be reading
out photocurrent given the low frequency behavior looks fine? The broad feature at ~80 kHz is the usual SR785 feature I guess, IIRC it's got to do
with the display scanning rate. |
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Tue Nov 24 12:27:18 2020, Koji, Electronics, Characterization, The dark noise of the Q3000 QPDs
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The amplifier BW was 400kHz at the gain of 1e7 V/A. And the max BW is 500kHz even at a lower gain. I have to setup something special to see the RF band
dark noise.
With this situation, I stated "the RF dark noise should be characterized by the actual WFS head circuit." in the 40m ELOG. |
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Mon Nov 14 08:34:45 2022, Camille, Optics, Characterization, transmission measurements through OMC #1 (before cleaning)
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[Camille, Koji]
Friday, Nov 11th, 2022
Setting up OMC #1 for transmission measurements: |
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Mon Nov 14 09:27:13 2022, Koji, Optics, Characterization, transmission measurements through OMC #1 (before cleaning)
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The measured total optical loss of the OMC was
1st: 0.015 +/- 0.003
2nd: 0.085 +/- 0.005 |
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Thu Nov 17 19:50:00 2022, Koji, Optics, Characterization, Conclusion on the cleaning of OMC #001
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Conclusion on the cleaning of OMC #001
- After a couple of first contact cleaning trials and deep cleaning, the total loss was measured to be 0.045+/-0.004.
This indicated a slight improvement from the loss measured at LLO before any cleaning (0.064+/-0.004). |
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Fri Dec 2 11:42:03 2022, Koji, Optics, Characterization, OMC #1 cleaning for water soluble contaminants
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[Camille, Koji] Log of the work on Nov 30, 2022
The following is the notes from GariLynn
Cleaning for water-soluble contaminants:
It uses deionized water instead of acetone.
Cleaning is based on this: LIGO-E1200326-v2
Your |
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Fri Dec 2 12:38:15 2022, Koji, Optics, Characterization, OMC #1 cleaning for water soluble contaminants
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Another set of FC cleaning was applied to FM1/FM2/CM1/CM2 and SM2. Some FC strings are visible on SM2. So I decided to clean SM2 as well as the cavity
mirrors close to SM2 (i.e. FM2 and CM2)
As a result, the bright scattering spot on CM1 is now very dim. And the loss was reduced to 4.0%. This is 0.4% better than the value before the |
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Fri Dec 2 23:58:33 2022, Koji, Optics, Characterization, OMC #1 cleaning for water soluble contaminants
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The second trial of the water scrub
A bright scatter is visible on FM1, so I tried water scrub on FM1. This time, both surfaces of FM1 and both surfaces of BS1 were cleaned.
Smaller Vectra swabs were used for the scrub. Then the water was purged by IPA splashed from a syringe. Right after that FC was applied. |
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Fri Dec 9 13:13:13 2022, Koji, Optics, Characterization, FSR/TMS/Spot Positions/Transmission
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[Camille Koji]
We quickly measured the basic parameters of the OMC as is.
=== FSR === |
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Mon Dec 12 19:04:40 2022, Koji, Optics, Characterization, FSR/TMS/Spot Positions/Transmission 2nd trial
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[Camille Koji]
We replaced CM2 with a PZT mirror subassembly serialized by PZT "13" (Attachment 1).
This made the transmission increase to 96.x%. Therefore the quick measurement of FSR and TSM were done. Also more careful measurement of |
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Mon Dec 19 18:51:50 2022, Koji, Optics, Characterization, TMS measurement with the PZT voltages altered
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[Camille, Koji] Log of the work on Dec 15, 2023
The vertical and horizontal TMSs for OMC #4 were measured with the PZT voltages scanned from 0V to 200V.
We concluded that this alignment nicely avoids the higher-order mode structure up to ~19th order. We |
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Wed Feb 8 16:10:52 2023, Stephen, Optics, Characterization, A+ OMC, Parallelism of HR Prisms 7x
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[Camille, Thejas, Stephen]
We set up the white light autocollimator in the Downs B119 cleanroom. (Nippon Kogaku, from Mike Smith).
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Thu Feb 9 15:54:41 2023, Thejas , Optics, Characterization, A+ OMC, Parallelism of HR Prisms 19x
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[Camille, Thejas, Stephen]
Continuing yesterday's efforts to measure the wedge angle of the back surface of the prisms. We completed measurement for all the 18 prisms.
The images below accompanying the readings represent the S2 crosshair image on top of the reticle, alighned for yaw. |
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Tue Feb 14 10:45:00 2023, Thejas , Optics, Characterization, A+ OMC Prism perpendicularity 27x
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[Camille, Stephen, Thejas]
Following the wedge angle measurements of the prisms, perpendicularoty of their bottom surface with respect to their HR surface was measured
usign the autocollimator. More info. about the procedure can be found in the OMC testing document. We want to set the requiremetns for perpendicularity |
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Tue Feb 14 22:52:35 2023, Thejas , Optics, Characterization, A+ OMC Prism perpendicularity of HR Prisms and BS 18x
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[Camille, Stephen, Thejas]
Continuing with the efforts to measure the perpndicularity.
Prism 15 |
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Wed Feb 15 17:40:21 2023, Thejas , Optics, Characterization, A+ OMC perpendicularity of hole prisms 20x
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[Camille, Stephen, Thejas]
Contnuing the efforts to measure and check perpendicularity: tombstone prisms with holes/ hole prisms (HP).
Note: Veritcal crosshair splitting can be seen in the some of the image. This is probably because the horizontal of the Al flat |
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Fri Feb 17 17:11:28 2023, Thejas , Optics, Characterization, A+ OMC beam-splitter prisms wedge angle measurement 11x
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[Camille, Stephen, Thejas]
Yesterday we measured wedge angle of the beamsplitter (BS) prisms. I reckon these measurements are not as important as the BSs will be used |
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Fri Feb 17 17:25:39 2023, Thejas , Optics, Characterization, A+ OMC Breadboard measuerements
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Yesterday we also measured weight and dimensions of breadboard. Error for the following measurements is same as the least count of the instruments used.
26
6149 g |
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Fri Feb 17 17:41:57 2023, Thejas , Electronics, Characterization, A+ OMC Piezos wedge angle
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[Camille, Stephen, Thejas]
PZT model: Noliac 2124
Qty: 18 (Sr. No. 30 - 48) |
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Mon Feb 27 17:40:27 2023, Thejas , Optics, Characterization, A+ OMC curved mirror characterization
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[Camille, Stephen, Thejas]
Today, before the ZYGO lab was cleaned and prepared for the cureved mirrors' radius of curvature (ROC) characterization, Mirror no. 6 was
mounted into one of the half inch mirror holders. The cleanliness of the envoronment and handling was not satisfactory. Tomorrow efforts will |
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Wed Mar 1 10:23:10 2023, Thejas , Optics, Characterization, A+ OMC curved mirror characterization
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[Camille, Thejas, Stephen]
Yesterday, efforts were made to measure ROC of curved mirrors (#6) in the ZYGO lab using a Fizeau Interferometer. Peculiar observation: Stray
fringes were seen that dominated the fringes that conformed with the expectation. The origin of these fringes is still not accounted for (see attached |
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Tue Mar 7 10:20:55 2023, Thejas , Optics, Characterization, A+ OMC Curved mirror radius of curvature
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[Camille, Stephen, Thejas]
Stephen returned the curved mirror #6 to Liyuan for point transmission measurement. We are now using #5 for to setup/align the ZYGO Fizeau
interferometer setup to characterize the curvature center of the mirrors. It was setup such that the focal point of the input reference sphere was coincident |
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Tue Mar 7 23:00:16 2023, Thejas , Optics, Characterization, OMC Lab clean up
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Today, Koji and I cleaned up the the lab space and made some space on the optical table for radius of curvature measurement of the A+ OMC curved
mirrors.
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Wed Mar 8 17:27:51 2023, Thejas , Optics, Characterization, A+ OMC Curvature minimum of curved optics
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[Stephen, Thejas]
Today, a more rigorous effort was made to re-measure the position of the optics forming the Fizeau cavity and re-position the curved optic to
get more contrasting fringes. Distance measurements were made using a Fluke laser displacement sensor. We obtained a contrasting fringe pattern but the |
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Fri Mar 10 10:23:08 2023, Thejas, Optics, Characterization, A+ OMC curved mirror radius of curvature
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OMC test set-up
Yesterday, laser beam output from the fibre follwoing teh mode-matching lenses was picked off and beam profile was characterized using beam profiler Thorlabs
BP209-VIS. |
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Fri Mar 10 11:12:57 2023, Thejas , Optics, Characterization, A+ OMC Curvature minimum of curved optics
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[GariLynn, Stephen, Thejas]
Yesterday, we placed an iris (borrowed from OMC Lab) infront of the spherical transmission sphere to limit the spot size, on the other end of
the cavity, to only the curved optic. This produced a crisp boundary for the interference pattern. We obtained some data at different imaging focal planes. |
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Tue Mar 14 10:41:06 2023, Thejas , Optics, Characterization, A+ OMC curved mirror characterization
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[Camille, GarriLynn, Stephen, Thejas]
Folllowing the replacement of the spherical transmission / reference mirror with a flat mirror, on Friday we were able to observe fringes that
facilitated characterization of the curvature minimum. |
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Tue Mar 14 12:12:41 2023, Koji , Optics, Characterization, A+ OMC curved mirror characterization
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RoC: 2.65m ! Interesting. I'll wait for the follow-up analysis/measurements. The RoC may be dependent on the area (diameter) for the fitting. You
might want to run the fitting of your own. If so, let me know. I have some Matlab code that is compatible with the CSV file exported from MetroPro data. |
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Tue Mar 14 18:24:03 2023, Thejas , Optics, Characterization, A+ OMC Curved mirror radius of curvature
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Today, I tried to measure the radius of curvature of the curved mirror using the input beam for the OMC test set-up. It was noticed that the half inch
curved optic (ROC=2.5 m), when placed within the Rayleigh range of the beam waist, did not focus the beam. This is probably becasue the beam diameter is
small for this optic's radius of curvature to produce any focussing. This can be illustrated even further using the JAMMT software by replacing |
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Tue Mar 14 20:06:03 2023, Koji , Optics, Characterization, A+ OMC Curved mirror radius of curvature
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If the mirror has the RoC, it works as a lens. And you should be able to see the effect in the beam profile.
Just what you need to do is to compare the beam profile without the mirror (or with a flat mirror) and then with the curved mirror.
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Wed Mar 15 15:28:24 2023, Thejas , Optics, Characterization, A+ OMC Curved mirror radius of curvature
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Thanks for teh comment Koji. Yes, I did see this effect by comparing the beam sizes with and without the curved mirror. But the observation did not conform
with the expectation that the beam should focus at a distance of 1.25 m from the curved mirror (as seen in the software images). So, I plan to
use some lenses to increase the beam waist and perform the measurement. |
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Wed Mar 15 17:07:35 2023, Koji , Optics, Characterization, A+ OMC Curved mirror radius of curvature
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| I hope you can find useful lenses from the lens kit in the cabinet. If you need more lenses and mounts, talk to our students in WB and the 40m. |
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Fri Mar 17 15:01:21 2023, Koji , Optics, Characterization, A+ OMC Curved mirror radius of curvature
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Thanks Koji, the lenses available in the cabinet in the lab actually sufficed.
Quote:
I hope you can find useful |
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Fri Mar 24 07:38:54 2023, Camille Makarem, Optics, Characterization, ROC measurements of the curved mirrors
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[Thejas, Camille]
21 March 2023
We made slight adjustments to the beam expander lenses in the ROC setup. The position of the second lens was moved slightly (a few mm) to improve |
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Fri Mar 24 07:47:37 2023, Camille Makarem, Optics, Characterization, ROC measurements of the curved mirrors
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[Camille]
22 March 2023
Beam profile measurements were continued for more of the curved mirrors. |
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Tue Mar 28 11:21:27 2023, Camille Makarem, Optics, Characterization, Sagitta measurements of curved mirrors
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[Camille, Stephen, Thejas]
Curved mirror sn02 was used to test the method for collecting Zygo measurements on the curved mirrors. The curved mirror was mounted with its back |
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Mon Apr 3 11:06:47 2023, Thejas , Optics, Characterization, Flat mirror flatness
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Data can be found in DCC document T2300050.
On Friday. Camille and I measured the flatness of the flat mirror. Tilt values (without subtracting tilt) were less than 100 nm and PV |
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Tue Apr 11 16:18:25 2023, Thejas, Optics, Characterization, A+ OMC Curved mirror radius of curvature
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Curved mirror radius of curvature raw data can be found in the DCC document: T2300050
The input beam falling on the curved optic was characterized. The beam waist and it's position was found by curve fitting gaussian beam
propagation formula in near field: |
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Thu Apr 13 07:47:28 2023, Camille Makarem, Optics, Characterization, Zygo setup for curved mirror measurements
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[Camille, Thejas, Stephen]
We modified the Zygo setup for measuring the sagitta of the curved mirrors. A mirror at 45deg was used to reflect the interferometer beam down
towards the surface of the table (see picture). A fused silica flat was placed horizontally with the surface of the table and was used as our reference |
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Fri Apr 14 15:52:53 2023, Camille Makarem, Optics, Characterization, Determining the curvature bottom of the curved mirrors
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[Camille, Thejas]
We repeated Zygo measurements (using the same setup and method as below) for curved mirrors sn07, sn11, sn12, sn18, sn19, sn25, sn26, and sn30.
sn11 and sn25 still show a large spread in angular measurements (see attached.) This is attributed to the low decentering values for these two |