| June 2, 2008 Getting up to Speed - MOSES E (ev) = (12400)/(Lambda À) MOSES - 100,000K (Transition Region) He II: 304À or 30.4nm He+ Ly(alpha) 1216À or 121.6nm ((INSERT LogT Graph)) ((INSERT MOSES Mirror System Diagram)) June 3, 2008 Getting Started - Setting up a Point Source ![]() A = Laser
B = Beam Splitter C = Pinhole D = Point Source The following is the procedure to which to translate a laser beam into a point source. -Level laser near, then far, by
using
pinhole and iris. Line up first close to laser for reference then
place pinhole on far side of table. Adjust until laser hits iris
same way as when close up.
-Insert objective (microscope
thingie)
which has limited focal point and might run out of range if you place
in too far. Let it be slightly out by a few millimeters for
adjustment later.
-Place ray splitter at an angle so that one may see the dimmer split, not the brighter one, on a piece of paper or wall opposite of the working side of platform. This is for focusing purposes later. -Screw in pinhole ALL the way, this is NOT to be adjusted later. Aligning the Point Source - Best done in dark -Get defraction patterns lined up
on
the wall where you had previously placed there (this is the dimmer part
of the splitted ray, which are actually two or three faint but visible
defraction patterns).
These are adjusting the x and y axis points. -Then adjust the z axis. This is done using the large round adjuster's connected to the microscope objective. -Now move to the spacial filter, which is what the pinhole/micro-objective is, and using the round adjuster surrounding the pinhole, NOT the pinhole itself, in conjunction with the two adjuster's used previously to find brightest point in x and y directions, direct the resulting beam of light through the pinhole into a point source which has little to zero defraction patterns visible. (This might be made easier if after you get it close enough, placing a card very near the end of the spacial filter and viewing details from there). Addition of a
Lens
![]() A = Laser B = Beam splitter C = Pinhole D = Point source E = Thin lens F = Plain waves G = Cube's Corner Retro Reflector Make sure all things are lined up as perfectly as possible, alignment will mean everything later. This means the lens must be flush and perpendicular to the z-axis, the laser beam axis, and cannot be tilted in either the y or x axis or your measurements will be off. Place lens on a slidable port as well as a rotational mount. This is for adjustments you might make in those dimentions. The following is the procedure to allign the lens: Aligning Lens -
Best done in low light
Before
you start: Check laser placement on a stationary reference card
which is placed far from laser point (after it is leveled) to ensure
the beam goes straight along a designated line which will corrospond to
where you place all following equipment. If the lasor is level
but not alligned to the table in this manner, things down along the
line might not recieve the beam's light.
1) Place lens close to where spots on wall directly behind laser are as close together as possible. Lens height is dependant upon this alignment, which tells you that you are hitting the center of the lens in the y direction. 2) Then, move the two spots to as close to the laser source as possible, adjusting the x-axis or tilting the lens back and forward slightly to do this (tilting should not be necessary but the set up might not be perfect and the lens could be seated slightly crooked in the z-axis). 3) Add previously adjusted spacial filter using a crows clamp as the placement of this objective will need pointing towards the lens precisely. The use of a stationary card might be helpful, but if you are doing this in the dark, not necessary. ![]() Crow's Clamp Also, place lens at the
approximate
focal point on an adjustable sliding platform. The lens table may
not be long enough to find it if in the wrong place and you'll want to
have some room to move the lens and experiment with where the focal
point actually is.
It should be noted that the addition of the Retro-Reflector is to point the resulting point source back towards the laser source, to which the beam will hit the beam splitter and make it's own light upon the wall if the lens is in focus. This fact in of itself is how we find the focus. By moving the lens (which should be on a slide table for adjustment of position in the z-axis, or the laser axis) one can find the point where the beam of light going back through the apparatus is at it's brightest point. This might sound confusing, but move the lens back and forth and see a small point brighten on the wall where you previously had focused the point source on, this is your focus range and you will see one point of brightening if you have the lens perpendicular to the z-axis. (Note: If there are two points of brightening, your lens is tilted slightly to the right or left and needs adjusting as this is an artifact of astigmatism). To test for perfect focus and to incorperate a test for astigmatism, do runs which consist of turning the lens +5 degrees from best estimated 0 degrees and -5 degrees. Use an Amp meter attached to a detector alligned to the dimmer spot produced by beam splitter to measure brightness of spot. If your allignments are good, the focal point should be at one bright point in your graphs you make of the measurements taken from the amp meter, averaged over 50 data points and allowed to repeat, not a moving average filter. June 4, 2008 June 3rd's experiment premise
used in runs done today.
See data sets of these runs: Practice Allignment ![]() A = D
B = da C = Theta D = y E = f F = depth of field ((INSERT HAND NOTES)) June 5, 2008 Worked on assigned program,
linked below.
June 6, 2008 9am: Presented assigned program in
IDL to REU's and mentors, based off the work-up Dr. Kankelborg gave me Spot Size Estimation
and using the image:
It worked, so I suppose it was ok. Read out as following: IDL>
.r focusprogram
% Compiled module: FOCUSPROGRAM. IDL> focusprogram % Loaded DLM: JPEG. N= 303741. x_o= 199.984 y_o= 310.036 The root mean square (RMS) spot radius is= 21.9481 % Compiled module: XTV. % Compiled module: XREGISTERED. % Compiled module: XPDMENU. % Compiled module: XMANAGER. Spent rest of day getting ready for Yellowstone trip, left at 3pm. June 9, 2008 Interferometers
Micheison Interferometer ![]() A = Plain waves
B = "Perfect" rectangle C = Cube beam splitter D = Test Surface E = Interference fringes F = Screen This tests a surface of unknown
quality against a higher dollar surface of known quality, near
"perfect."
The frindges will alter if test surface is imperfect in any way, and by the differences you should be able to determine relative quality. Fizeau Interferometer ![]() Fizeau Interferometer
*Note: B and C are same device* A = Spherical wave source B = Cube Beam Splitter (See C) C = Effect of Beam Splitter D = Partially reflective surface E = Test surface F = Screen G = Resulting fringe pattern Spherical wave version of Micheison Interferometer. Afterwards, worked on web-log and read up on the notebook Thom Rust gave me, "Space Optics Lab: Spherical Wave Interferometer." June 10, 2008 Issues came up mounting first
test mirror. Only post mount with side hole big enough was too
tall. Found a bolt that fit on the first mirror though.
Later found magnetic placing mount with slide pole and mountable slide pole which positioned the mirror well. Also was unable to find "sweet" spot for the "perfect" or test lenses to allign them with GRIN hole. Their radius of curvature must be placed precisely upon the GRIN hole and I could not seem to find it. Suggested changes: propose four sections of mounts for the following pieces... 1) For laser and polarizer
2) Cube beam splitter and GRIN lens 3) "Perfect Lens" - on slideable track 4) Test Lens - on slideable track June 11, 2008 Worked on web-log.
June 12, 2008 9am: Sun Lecture #1
Worked on alligning interferometer once more. Had issues getting light to transverse back through GRIN lens for allignment. Asked Tom Rust to meet next day at noon. June 13, 2008 Met with Tom and discovered a
method which seemed to work, an order to which to allign the
interferometer.
1) Allign Laser (make mark on
wall for future deviational allignments)
2) Allign cube beam splitter 3) Allign "perfect" lens 4) Place and allign GRIN lens (mount first) 5) Focus "perfect" lens through GRIn lens until beam has little deviational spread, beam keeps similar size no matter distance from screen (this is going to be rough estimate, perfect not necessarily possible). 6) Place and focus "test" lens with same procedure as "perfect" lens This method produced fringes, origins of which are questionable in reference to what we are looking for. June 16, 2008 Interferometer Procedure - Alterted and detailed 1) Allign Laser: appoint and
mark a spot across from table for laser reference.
2) Set "Perfect" Lens: Ensure reference spot and allowed beam are alligned once more as the addition of the lens can create a bending upon the laser light and move it from mark if mis-alligned. This is your "perfect" lens. 3) Set Cube-Beamsplitter: This is a temporary set up. Reference of position only for GRIN lens. 4) Set up GRIN lens: Allign first the mount to be square with the apparatus. Then adjust lens itself with the seat screws. Create point source to which alligns with "perfect" lens and cube beam splitter to which covers both centrally. Ideally the GRIN lens should be placed as close to the beam splitter as possible. 5) Remove Cube-Beamsplitter and focus "Perfect" Lens (PL): move enough out of the way to allow light from grin lens to hit lens undeviated and in essence allow light from the "perfect" lens (PL) to hit the GRIN directly. Locate beam of light from PL and place directly upon GRIN lens in it's smallest focused point, making the dot as small as possible. This should produce a light on the opposite side of the GRIN lens which should be moved to a central position, but NOT down the cavity of the laser. Place a separate flat beam splitter between laser and GRIN lens. ((Note:))Locate two points of light which are reflections of the GRIN lens from the laser. Assure the point of light you are using to refer to is indeed from your PL by placing an obstruction between the PL and the first objective infront of it (should be GRIN lens). After doing this, using the two reflection dots, allign the point of light from your PL to be centerally fixed between those two dots. After doing this, assure that the beam of light from you PL deviates as little as possible as you move the screen towards and away from the beam splitter, the dot not allowed to grow or shrink a good deal in essence. This means well collimated light and a good focus has been found. 6) Add Test "Unknown" Lens (TL): Procedure for alligning the test lens is the same for PL and the same warning note applies concerning the reflectoin points and the PL point. 7) Replace Cube Beam Splitter: By this point, placing the screen in the path of the beam splitters reflecting surface which makes the fringes accessable will allow one to see fringes. Analysis of this procedure Resulting fringes were confusing,
as many were found from several subtractions from set up.
Confusing in the sources and causes, which could be numerous.
Some might be from the following: - GRIN lens (large banded ones) - Cube beam splitter (small horizonal / veritical ones) - Metalic surfaces reflecting (corner fringes) Also laser emitted odd beam: pure red in center surrounded by a rather large bright halo of blue, causing shadows further down the apperatus. Cause currently unknown. Also, removal of cube splitter may have been unwise, as refraction within the cube can effect where focus point towards the GRIN lens is. Analysis of this short-sight tomorrow: - Snell's Law
- Fermat's Principle - Fresnel Equations June 17, 2008 9am: Solar Lecture #2
Snell's Law
ni / nt = sin(theta t) / sin(theta i) theta i ~ 45* - 0* (all others ignored for they would deviate out of cube and not reach the GRIN) ni = 1 (air) nt = 1.5 (glass) 1/1.5 = sin(theta t) / sin(45) theta t = 41.8* FOUND CUBE SPLITTER CORRECTION: focus
shift = t (n-1) /n = t (0.5) / 1.5 = 0.333 t
where t = thickness of cube June 18, 2008 ![]() Cube-Beamsplitter Ray Refraction Diagram s = arbitrary length
w = arbitrary length t = thickness of cubesplitter Theta i = angle of insident ray Theta t = angle of refracted ray P = Focal point before cubesplitter P' = Focal point after cubesplitter delta = difference between P and P' Revised
Procedure to Allign Interferometer
1) Allign laser (with dot on
wall)
2) Allign cube splitter - place shimms to allign two relecting spots which appear on wall. Make sure they return down laser cavity as best as possible as laser is optical axis. 3) Place "Perfect Lense" (PL) as close to alligned as possible, estimate how much shimming might be needed. 4) Place and allign GRIN lens- make sure both reflecting points from GRIN return to laser cavity. 5) Allign PL - Do this by placing a flat beam splitter between and focusing it to smallest non-deviating point out or near the GRIN lens reflection spot which is nearest to center of laser cavity. 6) Do same with "test mirror" (TM) - cover with dimming screen to allow the light from the lens later to not be overshown. 7) Adjust TM until interferometer is alligned and produces straight fringe lines. June 19, 2008 1pm - Meeting with phone
conference
3pm - weekly meeting Worked on weblog all day, was really behind. June 20, 2008 Set up interferometer for tour.
Placed hardware and posts in ultrasonic cleaner. Was unable to set up anything today, do it monday. June 23, 2008 Set up interferometer in the
clean room. Went over clean room procedures.
Had issue with odd pattern coming from either GRIN lens or laswer. They were like small dimples in a small circular pattern. Different from dust. Turned the GRIN around and they mostly disappeared. However on the far top right of optical surface, large pieces of dark substance shadow appeared. It was all a bit odd. 4pm - went to doctor June 24, 2008 June 25, 2008 Helios not working again.
June
26, 2008Radius of curvature for Lag Mirror - 9480 +/- 5 mm Table = 48 x 168 post holes, or inches 9am - Solar Lecture #4
11am - Doctor's appointment 2:30pm - arranged set up roughly, will make more precise distances after meeting. 3pm - Meeting with advisors June 27, 2008 Space on Table available = 480
inches
Space needed = 372 inches Arrange table thus: Lag Mirror to First fold mirror
(2" mirror) = 140 inches
Arranged all components on table into places. Lag mirror not yet
installed until all distances are varified, leaving least amount of
exposure time on table for Lag.First fold mirror (2") to Second fold mirror (2") = 140 inches Second fold mirror to Interferometer = 94 inches +/- addition adjustment in finding fringes. Set interferometer on mount which allows distance adjustment. June 30, 2008 Question came to weather the
first fold mirror, the one which is pointed towards the Lag, is big
enough to encompass entire beam coming from the Lag. The formula
considering the size of the converging cone at any point, namely 140
inches from mirror which is what was in question was the following:
((INSERT CALCULATIONS)) In short, we need a bigger mirror. A 1 foot radius mirror thus was placed as first fold mirror. July 1, 2008 9am - Solar Lecture #5
Fine tuned distances and placed
lag mirror. Began search for returning spot from lag on interferometer.
July 2, 2008 All day conference in Department.
Each mentor talked on their projects.
July 3, 2008 Got the Lag and fold mirrors all
alligned and pointing back to laser. Assembled interferometer.
Found all three orders, pointed first center order (the brightest) towards interferometer. Attempted getting spot on interferometer, however lost second fold mirror allignment and left it for monday. July 7, 2008 Removed GRIN lens and realligned
mirrors using coherent laser light. Replaced GRIN and with some moving
around found I could reallign interferometer without having to readjust
reference lens.
Hoever found horizonal motions merely altered which order light reflected off of Lag. Motions being position of Lag light coming in to hit GRIN. So horizonal and vertical motion can only be done to mirror, however directly correcting by tilt adjustments of small 2" secondary fold mirror itself, leaving Lag unmoved. Keeping in mind though that Lag's order ranges can fade from misallignments so Lag must be relatively close to centered on interferometer and adjusting using second fold mirror should be for only fine tuning. July 8, 2008 Completely disaasembled
interferometer and attempted reallignment again.
July 9, 2008 11am - Doctor's appointment
Got mirrors alligned again, left interferometer alligned at end of day. Attempt to find spot tomorrow. July 10, 2008 9am - Solar Lecture #6
Changed mount for interferometer, Tom needed larger sliding adjuster. Refitted mount with posts to make height requirement for Lag mount, which is at same height as future project MOSES mirror is. July 11, 2008 SUCCESS! Found spot of center of
curvature to Lag on interferometer. Managed to track through the
"perfect lens" and onto cube beam splitter.
However, proved too dim once through splitter, could not find spot to lay it on GRIN lens for allignment. 1pm - Doctor's appointment. July 14, 2008 Continued searching for spot
through GRIN. Found it eventually as a 2cm smeer of light which
oscillated quite a bit.
However was quickly lost due to dimming by the addition of the cube splitter. More dimming is assumed when adding perfect lens. This presents a problem with brightness ratio between the perfect lens and the lag mirror. A similar but reverse problem found before using a smaller and much closer mirror in the beginning trials. The problem being one is much brighter and will drown out any fringe contrast. To correct this before a screen was used and placed infront of second brighter mirror. This solution cannot work as the problem is with the first lens which leads to the dimmer Lag mirror. Meaning if I dimmed perfect lens, it would also dim Lag, unhelpful. Possible Solution: Use a pinhole iris obsiticle where it allows all light from Lag and limited light from PLens. This should dim amount of leg from PL and allow all light avaible from Lag. Testing this tomorrow with using a camera on spots from cube beam splitter to find fringes (lag spot too small to see with eye). July 15, 2008 Tom was sick today, so no camera
or software available.
July 16, 2008 Tom still sick, no camera.
July 17, 2008 3pm - Meeting
Dr. Kankelborg tanked our pinhole
iris dimmer plan in today's meeting.
Even though the light from the perfect lens is beging partly blocked out, the portion which makes fringes with the Lag spot is only as big as the Lag beam. So basically the iris blocks NOTHING towards dimming the perfect lens light which would be affective in balancing contrast ratio. However, Dr. Kankelborg still believes dimming should not be necessary and that Lag light should be bright enough. Lag results are showing otherwise, but I will try again. July 18, 2008 Got camera placed, waiting on
another small mirror to bounce light from beam splitter into camera to
see fringes.
However, had a major issue with computer anyway. It would not install Fish Camp Starfish camera software called Nebulosity. 7pm - MOSES movie interview They said I did such a good job
as an interviewee that they asked all the questions instead of skipping
some to get it over with! Yay!
July 21, 2008 July 22, 2008 July 23, 2008 July 24, 2008 July 25, 2008 July 26, 2008 July 27, 2008 July 28, 2008 July 29, 2008 July 30, 2008 July 31, 2008 August 1, 2008 ***07/28/08 1:40 pm*** ***END OF CURRENT UPDATE*** |