A111Q3 QQ1372

NBSIR 88-3092

SYSTEM FOR MEASURING OPTICAL

WAVEGUIDE INTENSITY PROFILES

Lee E. Larson

Donald R. Larson

Robert J. Phelan, Jr.

National Bureau of Standards

U.S. Department of Commerce

Boulder, Colorado 80303-3328

August 1988

QC

100

.056

88-3092

1988

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SYSTEM FOR MEASURING OPTICAL''^

WAVEGUIDE INTENSITY PROFILES

Lee E. Larson f

Donald R. Larson

Robert J. Phelan, Jr.

Electromagnetic Technology Division

Center for Electronics and Electrical Engineering

National Engineering Laboratory

National Bureau of Standards

Boulder, Colorado 80303-3328

t On leave from Denison University

Physics Department, Granville, OH 43023

August 1988

U.S. DEPARTMENT OF COMMERCE, 0. William Verity, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Contzents

Page

1 . Introduction 1

2. Operation 3

3. Construction 7

4. System Tests 9

5. Software 12

6. References 17

Appendix A: Drawings of Parts 18

Appendix B: List of Commercially Available Parts ... 30

Figures 32

iii

System for Measuring Optical Waveguide Intensity Profiles

Lee E. Larson*, Donald R. Larson, Robert J. Phelan, Jr.

National Bureau of Standards

Electromagnetic Technology Division

325 Broadway

Boulder, CO 80303-3328

We have developed a computer controlled system to

measure the intensity profile of optical waveguides.

Knowledge of the intensity profile provides an indication of

the shape of the waveguide , and therefore the degree to

which light can be coupled to the guide from an optical

fiber. This report describes the construction and operation

of this system.

Key words: computer control; coupling; mode intensity

profile; optical fiber; optical waveguide

1 . Introduction

The Coupling Efficiency Measurement System (CEM) was developed to

measure the intensity profiles of optical waveguides. Knowledge of

the intensity profile gives an indication of the shape of the

waveguide, and therefore the degree to which light can be coupled to

the guide from an optical fiber, at least qualitatively.

We perform an entrance face scan with this system, where the

incoming radiation is focused to a small spot and then moved around

on the entrance face of the waveguide. All the light from the output

is collected and directed to the signal detector. A plot of the

output signal vs position of the entrance spot provides the intensity

profile. An entrance face scan gives results which are identical to

the more familiar near-field exit face scan[l].

*0n leave from Denison University, Physics Department, Granville,

OH 43023

1
In principle if waveguides supporting many optical modes are measured,

the intensity profile closely matches the index of refraction profile [1].

If single mode waveguides are used, the index profile can be derived from the

mode profile [2,3]. Here, however, our primary interest is in measuring the

profiles to assess the efficiency of coupling light from a fiber into a waveguide

A schematic of the system is shown in figure 1. It consists of four

subsystems; Entrance Optics, Stage, Exit Optics, and Detection System. The

Entrance Optics consists of (a) a source of light (He-Ne laser at the moment;

at a later time laser diode sources at 750 nm, 1.3 and 1 . 5 /xm may be added),

(b) a beam splitter which sends a portion of the incident light to a reference detector, (c) a chopper so that lock-in detection can be used,

(d) a spatial filter, and (e) a microscope objective which focuses the

incoming radiation to a small spot on the waveguide face (endfire coupling)

The spatial filter and focusing optics are mounted on a single-axis stage and can be moved in the direction of beam propagation. This stage makes it easy

to accommodate waveguides with different physical dimensions. Other

components in the Entrance Optics subsystem are rigidly mounted to an optical

breadboard.

The Stage has three controllable axes, each one of which can be moved

with steps as small as 0.05 /zm. This stage holds the waveguide being tested

as well as the Exit Optics subsystem. In operation, we move the waveguide

and Exit Optics around in the fixed input beam, accomplishing an entrance

face scan. This stage is fully computer controlled.

The Exit Optics subsystem has: (a) a microscope objective to collect the

light which is guided by the waveguide, (b) an adjustable aperture to

eliminate scattered and unguided light, and (c) a detector. This system is

mounted on a small manual 3-axis stage which is fastened to the computer

controlled stage. This small stage allows the exit optics to be focused and

aligned with the waveguide.

The Detection System consists of two detectors, one to measure the dc

reference signal, the other to measure the chopped radiation which has been

guided by the waveguide. For 633 nm measurements, these are Si photodiodes.

The detectors must be changed to make Infrared measurements above 1 nm. The

currents generated by the two detectors are converted to voltage signals by

op amps wired as current to voltage converters. These voltage signals are sent to a lock-in amplifier. When the lock-in amplifier is run in the

"ratio" mode, it divides the chopped input signal by the dc reference signal

and provides this ratio as its output. The effect of using this ratio mode

is to eliminate the dependence of the results on the source intensity. We

found in the course of our testing that, despite using this procedure, noise

with relative intensity of about 1% was still present when the source was a He-Ne laser. Replacing the He-Ne source with a collimated laser diode

operating at 750 nm reduced the noise by about a factor of 5. Data from the

lock-in amplifier are sent to the control computer over the GPIB bus.

2
To use the system, the waveguide is mounted on its holder, and the stages

are moved manually until light is coupled through the guide and its intensity

is maximized. Then the computer moves the stage in a grid pattern, scanning

the entrance beam over the face of the waveguide and recording the intensity

of the coupled light with the lock-in amplifier. Data are written to a disk

file, and are processed in a separate operation to provide a graphical output

of the intensity profile.

The system has other uses. We have used it to measure a pinhole, and

have looked at intensity profiles from a single mode optical fiber (both of

these measurements were made while we were testing the system) . We also used

it to measure the intensity variations of light from a fiber as the exit end

of the fiber was moved over dimensions of about 20 mm, to see if the power

coupled through the fiber varied as the curvature of the bends was changed.

With the substitution of a fiber coupler for the entrance objective and

holder, the system can be used to pigtail fibers to waveguides. The fiber

will be held stationary while the substrate is moved around to maximize the

coupling of the light. Then the fiber will be fastened to the waveguide with

uv cured epoxy. At the moment angular positioning of the fiber must be done

manually

2 . Operation

We assume that the system is set up: cables are connected to the

computer, optics are set up and aligned, etc. If the system is not set up,

refer to Section 3, Construction.

The following sign conventions and definitions will be used throughout

this report. As viewed along the direction of light travel (looking at the

entrance face of the waveguide) , the X direction is horizontal with positive

to the right, the Y direction is vertical with positive up, and the Z

direction is along the optical axis, with positive away from the laser.

The following operating instructions are written specifically for the

hardware we chose for the system. This has been done solely for the

convenience of the operator. In most cases, other similar components could

be chosen which would perform as well. If different components are used,

then these operating instructions must be altered to match the hardware

selected. We do not imply by our use that the hardware chosen is best for

the purpose, nor do we endorse or recommend it.

1. Turn the system on. Turn on the power to the laser, chopper, detector

amplifiers, computer controlled stage, lock-in amplifier, and computer.

2. From the DOS prompt on the computer, run the program NANOMOVR. A

"bootable" disk is available for a floppy-based system; this disk is labelled

NANOMOVR. In a hard disk system, change to the proper subdirectory and start

the program.

3
3. Follow the prompts on the screen. When asked if you want to unpark

Nanomovers, answer Y(es), To unpark all Nanomovers at the same time, press

the F4 function key followed by U(npark)

4. The stage screen should now appear. When choices appear at the top of

the screen, press M (for move)

5. Install the substrate. In general, it should be centered in the holder,

or be offset from the stage center in the +X direction. (The travel of the

output optics is limited in the direction toward the stage; it will be

impossible to align the output optics with a waveguide which is too far in

the -X direction.)

6. The next step in the operation of this system involves moving the

computer controlled stage. The stage is moved by pressing keys on the

computer keyboard. The X axis is controlled by the columns of letter keys at

the left edge of the keyboard. The Q and W provide fast - and + motion, the

A and S provide medium speed - and + motion, and the Z and X provide slow - and + motion. The Y axis is similarly controlled by the E-R, D-F,and C-V

keys. The Z axis is controlled by the T-Y, G-H, and B-N keys.

The 4 key sets all three stages to a reasonable default position, and the 3

key sets all three stages to 0. CAUTION: Be certain when using the 3 or 4

keys that the stage will not hit parts of the fixed system. TO STOP THE

STAGE AT ANY TIME, PRESS THE SPACE BAR.

7. Couple light through the waveguide. In general this procedure is easiest

with the chopper turned off. Set up a card to use as a screen in the

vicinity of the output optics aperture and focus the output optics to give a sharp image of the end of the substrate. Focus the incoming light onto the

entrance face of the substrate. Coarse focus can be accomplished with the

manual input stage. Use the microscope provided to view the entrance face of

the waveguide. This will be an aid in focusing the light on the entrance

face and in locating the waveguide.

Now move the stage as outlined in Step 6 until light travels through a waveguide. In general, the Y position is set correctly if light just grazes

the surface of the substrate. As the computer controlled stage is moved in

the X direction, the focusing optics must be moved manually so as to keep the

two objectives aligned. Light coupled through a waveguide shows up as a small bright dot on the screen.

Once the waveguide has been found, remove the screen, and let the light

travel through the aperture to the detector. The image can be lined up so it

passes through the aperture to the detector by adjusting the manual stage

holding the output optics. Normally the waveguide image should be focused

between the aperture and the detector, so that the image nearly fills but

does not overfill the detector. Then the aperture should be closed to just

block the stray radiation. Now turn on the chopper. We have made most

measurements with a chopper frequency of about 500 Hz.

4
8. Adjust the lock-in amplifier so that it indicates the ratio of signal to

reference voltage. If the signal appears noisy, check the size of the dc

reference signal. It should be in the range of 1 to 2 volts. (If the

reference signal is too small, the discrete nature of the A/D converter will

make the ratio signal appear noisy; if the reference signal is too large, the

signal amplifier will overload when a reasonably large output is requested.)

If the reference signal is not in the correct range, adjust the feedback

resistor on the reference amplifier until it is correct.

Once the lock-in amplifier is adjusted, peak the signal by making small

motions in the computer controlled stage. The X and Y positions should be

adjusted with the Z-X and C-V key pairs, a single step at a time until the

lock-in amplifier signal is maximized.

(These fine-adjust keys allow the stage to be set with 0.1 /xm resolution.

In addition, the anti-backlash feature is enabled for these keys. The antibacklash feature is disabled for the medium and coarse adjustments to make

continuous motion smoother. The motions used under program control have the

anti-backlash feature enabled; therefore for consistency between keyboard

adjustment and program adjustment, the final X and Y motions in the

maxin .zing process should always be made with the fine-adjust keys. This is

not so critical for the Z motion; the Z motion is not adjusted by the

program, and the depth of field of the focusing optics is a couple of /xm, so small inaccuracies in the Z motion will not affect the results.)

9. Press the FIO function key to get back to the main menu. Press P for

program, select the default BASIC by pressing <EIET>, and interpreted BASIC

will start. Type RUN CEM to start the control program. The program requests

the extent of the X and Y motions, the number of steps to use, the lock-in

amplifier time constant, and the number of readings to signal average.

(The program waits a settling time of twice the value you provide for the

lock-in amplifier time constant. If the signal is noisy, the lock-in

amplifier can be read more than once at each data point, and the results

averaged.

)

The program will now start, and "quick look" data will be graphed on the screen. The reading in the lower left corner of the screen is the actual

data from the lock-in amplifier.

After all data are taken, the program gives an option to save the

information to a disk file. Follow the screen prompts carefully. The data

file is in the format of a SURFER CRD file and can be used directly by the

program SURFER for drawing contour lines or intensity profiles of signal

voltage

10. To get back to the Nanomover screen, type SYSTEM. To quit, from the

Nanomover menu type Q, and when asked if you want to park Nanomovers, respond

with Y(es)

press function key F4 to choose all motors, and press P(ark).

ALWAYS TERMINATE OPERATION AS DESCRIBED ABOVE SO THE NANOMOVER SYSTEM WILL

NOT LOSE ITS ORIENTATION.

5
11. Software program SURFER can be used to draw contour lines (Section 11.1) or intensity profiles (Section 11.2) of signals.

11.1 Contour Lines. On a computer which has SURFER loaded, get into the

SURFER subdirectory and type TOPO FILNAM where FILNAM is the name of the data

file containing a run of data. FILNAM should include disk drive and/or

subdirectory. An extension of GRD is understood.

Information presented on the screen includes the minimum and maximum Z

signal. To draw 10% contour lines, compute 10% and 90% of the difference

between minimum and maximum Z values. Then select Level, fill in Minimum

contour with the 10% number. Maximum with the 90% number, and Interval with

the 10% number. Press ESCAPE to get back to the main menu.

At any time a screen graph can be seen by pressing function key F2.

Some useful options include:

Output: Sends output to plotter. Use defaults; change last choice to Yes.

Title: If a title is desired, select Title option and enter.

Grid: Select to turn grid lines on if desired.

Scale: Used to change the size of the plot.

Coniines : Allows contour lines to be labelled, changes smoothing

options

Equip: Used to change plotter type, screen colors, etc.

Special keys and Function keys have the following uses:

ESCAPE:

FI:

F2:

F3:

F4:

Shft-F4:

Back up one menu choice; return to next screen when viewing graph.

Help

View display on screen

Return to Main Menu

Stores highlighted value as a default for future graphs.

Stores all current settings as defaults for future graphs.

In general, defaults have been stored so that a minimum number of changes

need to be made for good displays with data from the CEM system.

11.2 Intensity Profiles. To draw intensity profiles, get into the SURFER

subdirectory and type SURF FILNAM where FILNAM includes drive and/or path

information.

Function key F2 will draw the intensity profile on the screen.

Useful options include:

Base: Determines whether to draw base. Default is Base Off.

Title: Use this option to add a title to the plot.

Axes: Plot and label axes. Default has X and Y axes plotted.

Titles can be added, and Z axis can be plotted as well.

Size: Change the size of the overall plot, and change scale of Z axis

relative to X and Y axes. Default fills a normal sheet of paper.

6
Output: Make a hard copy of intensity profile. Use the defaults on

the menu, but answer Yes to last question.

The special keys and function keys have the same meaning as in TOPO, and

are described in the previous section.

3. Construction

The CEM System is made up of commercially available components wherever

possible, to keep custom machining to a minimum. Custom made parts consist

of 11 different types: detector holders (2), substrate holder, three

different thickness spacers, five different optical mounting platform parts

and table legs (4)

Drawings of these parts are included in Appendix A.

Letters in curly brackets refer to the item in the drawings. A list of

commercially available parts to make up the remainder of the system is

included as Appendix B. This list is provided as a convenience to others

building such a system. In the following description, the numbers in curly

brackets refer to the numbers on the list of parts.

To make the construction details clear, we describe the system as a combination of subsystems.

The optical axis for the system was set at 5.5 inches, determined as a convenient working height for the computer controlled stage.

3.1 Optical Platform. The system is built on a 2 by 4 foot optical

breadboard {1}. This breadboard is not vibration isolated, and providing

this isolation could possibly improve the system resolution.

3.2 Source and Entrance Optics. These parts are assembled as shown in

figure 2. The system is designed to hold several sources (lasers) of

different wavelengths, and to have a beam switching mirror which will easily

let light from any one of the sources into the entrance optics. However, at

this time the only source used is a 1 mW helium-neon laser (2). This laser

is mounted in an adjustable mount to allow easy height adjustment (3). The

mount is spaced from the post by a spacer (A) to put the beam on the correct

optical axis.

A beam splitter (4) is used near the laser to send a portion of the light

to a reference detector {B),{5). The output of this detector is sent to the

lock-in amplifier and is used to ratio the main signal to remove noise due to

laser intensity fluctuations. The light is then sent through an optical

chopper {6} so that lock-in detection can be used.

The entrance optics are mounted on a custom made mounting plate (C) which

is fastened to a one axis stage (7). This stage is in turn mounted on an optical table (D) , (E) to set the optical axis at the correct height. Two

components are fastened to the mounting plate: a spatial filter assembly (8;

which is raised by a spacer (F) to the correct optical axis height and a

7
microscope objective holder (9). Three different microscope objectives {10}

with powers of 20X, 40X, or 60X can be used to couple light into the

waveguide. The objective holder and spatial filter are mounted at

approximately the "tube length" of the objectives apart, a distance of 160

mm.

3.3 Computer Controlled Stage and Substrate Holder. Refer to figure 3. A

three axis precision computer controlled stage {11} is used to move the

substrate and exit optics in the entrance beam. A bracket assembly (G} , (H)

which fastens to this stage supports the substrate holder {!) and the exit

optics. A spacer (J) is placed between the bracket assembly and the

substrate holder so that it is properly positioned. The substrate being

studied is gently clamped to the holder using 1/2" diameter Teflon washers

which are tightened against the substrate by thumbscrews. The bracket

assembly also supports the exit optics described in the next section.

3.4 Exit Optics. The exit optics are fastened to a mounting plate (K)

which is held to the bracket assembly by a small manual 3-axis stage {12}.

The manual stage allows the optics to be aligned and focused relative to the

substrate. When the measurements are being made, however, the exit optics

assembly does not move relative to the substrate holder. The computer

controlled stage moves both the substrate and the exit optics as a fixed

unit. The arrangement is illustrated in figure 3.

There are four components which make up the exit optics. A lOX

microscope objective {13} held in an objective holder {14} is used to form an image of the exit face of the waveguide. An aperture {15} is used to

eliminate light not guided by the waveguide, and a detector {B},{16} is used

to measure the signal. The objective lens is mounted near the substrate end

of the mounting plate, and the detector is mounted near the far end. The

aperture is mounted approximately in the center. The horizontal Z position

of these components is not critical. The X and Y locations of the detector

and aperture assemblies are adjustable, and must be set so that light from

the waveguide falls squarely on the detector.

3.5 Electronics. The signals from the detectors are amplified by op amps

connected as shown in figure 4. The op amps are powered by a small modular

+/- 15 volt power supply. The signal from the reference detector is wired to

the reference signal input of a lock-in amplifier {17}, and the output of the

signal detector is sent to the main lock-in input. The output of the lock-in

is sent to the control computer over the GPIB bus.

The computer controlled stage must be interfaced to the control computer.

See the stage manual for instructions.

3.6 Microscope. A microscope {18} is used as an aid to coupling the light

into the waveguides. Its base sits on an unused part of the optical

breadboard, positioned so that its head can be placed over the entrance face

of the waveguide

8
3.7 Setup. First, all components should be arranged as described in the

previous sections. The laser is polarized; if its plane of polarization is

important to the measurements to be made, rotate the laser in its mount until

the beam has the proper orientation. The direction of polarization is

indicated on the back of the laser. Place the chopper in the beam as shown

in figure 2; do not run it, but place the blade so that light passes down

through the system.

Next, align the input optics. With the entrance objective and spatial

filter elements removed, align the laser beam so that it is level and passes

through the center of the lens mounts. Then replace the lenses and spatial

filter pinhole. Adjust the position of the reference detector and/or beam

splitter until the reference beam falls in the center of the reference

detector. Next place a card at the entrance objective holder, before the

lens. Adjust the position of the pinhole until a symmetric image is present.

Then adjust the focus of the spatial filter lens until the central spot is

brightest and the least light is present in the diffraction rings. The

position of the pinhole may need to be adjusted again to keep the image

symmetric. Remove the card and check to be sure that the expanded beam from

the spatial filter is centered on the entrance objective. If it is not,

slight adjustments may need to be made to the position of the laser. Once

the spatially filtered light is centered on the objective, a good image

should be formed at the position of the substrate entrance face. Check the

quality of the out-of-focus image on a card; be sure it is symmetric and

evenly illuminated. Repeat this entire procedure if necessary.

Connect the detector amplifiers to the detectors and connect the power to

the amplifiers from the power supply. Connect the reference detector output

to the lock-in reference detector input (ADC 1 on the EG&G 5209), and connect

the signal detector output to the main lock-in input. Connect the computer

controlled stage as described in the stage manual. Motor 1 is wired to the

top connector, 2 to the center one, and 3 to the bottom. Plug in all ac power cords.

Install the substrate and locate a waveguide as described in Section 2,

Operation. Once the waveguide is guiding light, adjust the manual stage

position until the light passes through the center of the aperture. Adjust

the focus of the exit objective using the Z axis of the manual stage until

the beam focuses between the aperture and the detector. Then adjust the

detector mount until the image is centered on the signal detector. Once this

procedure is complete, turn on the chopper.

The system should now be set up for most measurements.

4. System Tests

We performed a series of tests designed to show that the system is

functioning and to explore its limitations. These tests are described in the

following sections. Two types of information are presented in the figures;

9
a) contour plots of intensity vs X-Y position with contour lines referenced

to the maximum signal and drawn at 10% intervals, b) relative intensity

profiles as a function of X-Y position.

4.1 Initial Test Using a Pinhole. We Inserted a 25 /zm pinhole in the system

at the waveguide location, and scanned it. The entrance objective had a power of 20X and a NA of 0.4. The results are shown in figures 5 and 6.

Figure 5 shows the intensity contour plot and figure 6 displays the intensity

profile. The step size was 1 ^m. The data are basically what we expect for

a pinhole source of this diameter, confirming that the movement of the stages

is at least roughly correct. By looking at the most dense distribution of

contour lines, we see that the beam size of the entrance beam is about 1 ^m.

4.2 Single Mode Fiber. We measured the intensity profile of a fiber which

supports a single mode at 633 nm. The advertised core size is 5 /zm.

For our first attempts we used a piece of fiber about 2.5 cm long. The

results were difficult to interpret, particularly when the entrance light was focused with a high NA lens. After noticing that the entire fiber assembly

was glowing from end to end, we decided that the difficulties were possibly

caused by cladding modes which had not radiated away and which were fairly

sizeable in comparison with the core signal. We then replaced the short

fiber with a piece about a meter in length clamped to the waveguide holder at

each end and looped around the apparatus. Results with the longer fiber were much closer to what we expected.

Since the waveguides we use are all relatively short, this experiences

suggests that we must be very careful to use the aperture in the exit optics

system to mask light from outside the guide. In addition, the entrance

objective should have a relatively low NA. A NA of about 0.4 is a good

compromise between having the spot size small (about 1 /zm) and not having

excessive radiation outside the waveguide.

Figure 7 shows the intensity contours when the system was incorrectly

focused. A similar plot with the system correctly focused is shown in figure

8. The pattern is circular, and the diameter of the 10% contour line is just

over 5 /zm. The pattern of the out-of-focus plot is broader than the one which is correctly focused.

The profile cross section of a single mode fiber is often Gaussian.

Figures 9 and 10 illustrate the horizontal and vertical profile cross

sections, with a Gaussian function superimposed. There are small variations,

but in general the fit is quite good.

4.3 Waveguides. We measured intensity profiles for several potassium ionexchanged glass channel waveguides. These were all on a single substrate.

The results are shown in figures 11-15. In addition to the intensity

profiles, corresponding mechanical surface profiles near the ends of the

guides are shown. The potassium ion-exchange process used to increase the

refractive index of the glass also causes a slight swelling of the glass.

10
For the mechanical surface profiles, the horizontal axis is in ^m, and the

vertical axis is in angstroms. The surface of the guides are readily

apparent in the intensity profiles; the spread in contour lines above the

surface is due in part to the finite size of the spot on the entrance face.

The intensity profile shown in figure 11 indicates that the waveguide is

at an angle relative to the X axis. We believe this is real, and that there

is a ripple in the glass in this region. The ripple does not show up in the

surface profile, because the surface profilometer electronically levels the

surface

The most interesting observation relates to the symmetry of the guides.

The intensity profiles for guides shown in figures 12 and 15 are nearly

symmetric, as are the surface profiles. In cases where the intensity

profiles are asymmetric (figures 11, 13, 14) however, the surface profiles

taken near the ends of the guides are also asymmetric. In fact, for the

guide shown in figure 14, both the intensity profile and the surface profile

show two peaks near the center of the guide. At least on a qualitative

level, then, the mechanical shape of the guide and the "optical shape" are similar

4.4 Intensity variations of light from a fiber. In experiments we have

designed to measure the response uniformity of detectors, we plan to couple

light into a fiber, and then to move the fiber around the detector surface

while we record response as a function of surface position. The question

arises as to how much variation is caused by changing the bends in the fiber

during the course of the measurement. We have used the CEM system to measure

this variation.

We used an auxiliary laser and fiber coupler to couple light into the

fiber. These components were rigidly mounted to the optical breadboard. The

beam splitter, reference detector, and chopper were moved to this auxiliary

beam and serve the same purposes here as for the usual measurements . The

exit end of the fiber was clamped to the waveguide holder, and the output

radiation was directed to the detection system.

We moved the exit end of the fiber over a 22 by 22 mm square pattern and

recorded intensity as a function of position. The results are shown in

figures 16-21. The contour plots have lines drawn at 20% intervals between

the minimum and maximum signal levels.

The source for the results shown in figures 16-18 is a helium-neon laser.

The maximum variations from the mean value are of the order of 1%. The source for the results in figures 19-21 is a laser diode which operates at a wavelength of 750 nm. With this source the output is much more stable, with

maximum variations of about 0.2%. When comparing the two dimensional

intensity profiles shown in figures 17 and 20, note the change in the

vertical scale.

11
Our results indicate that the variations, at least above the 0.2% level, are due to the source rather than the variations in fiber loss due to changes

in the bends

4.5 Stage Motion. In order to test the accuracy of the stage motion, we set

up a laser interferometer and compared the interferometer readings with the

positions to which the stage was directed by the computer. We tested only

the Y axis stage which provides the vertical motion. Since this stage is

under the most mechanical load, it should give us a worse case indication of

the accuracy.

Extensive tests allow us to draw the following conclusions, (a) The

stages used in this system have an automatic scheme for removing backlash

termed the Lost Motion (LM) control by the manufacturer. The direction and

extent of stage motion to remove backlash can be controlled by the operator.

At least for this stage, much better results are obtained with the LM

direction negative, (b) An LM value of 2 (20 /xm) seems adequate. Nothing is

gained by increasing this value. (c) A relatively low stage velocity is

marginally better than a high one.

One of the major limitations to our tests seem to be temperature changes

in the room. The stage manufacturer notes that temperature changes causing

length changes in the screw constitute a major source of error. This is

confirmed by Figures 22-24 which show the change in Interferometer readings

when the stage was not moving, taken during the morning when the temperature

of the laboratory was noticeably increasing. The 500 readings were taken

over a period of about 10 min. Figure 22 shows that the path length changed

about 0.5 /xm over this time. To get a measure of errors between adjacent

readings and between those which are 20 units apart, we drew the histograms

shown in figures 23 and 24. Figure 23 shows that, typically, adjacent

readings differ by less than 0.1 /xm. This is essentially a measure of the

noise in the measurement system, since the stage was not moving. The data

shown in figure 24 are an indication of the drift of the system with time.

Subtracting points which are 20 readings apart results in a significant

number of cases where differences are up to 0.3 /xm.

Typical stage data are shown in figures 25-27. We see maximum errors

over one turn of the micrometer screw (500 ^m) of about 1 /xm. Figure 26

shows that most adjacent points representing stage motion of 1 /xm show errors

less than 0.1 /xm, with a smaller but significant number with errors of up to

0.2 /xm. For readings over 20 /xm, a typical width of a waveguide scan, figure

27 shows errors up to 0.3 /xm.

Our conclusions from a large series of measurements such as those just

described is that the stage meets our requirements for accuracy.

5 . Software

The software to run the GEM system consists of two programs, a compiled

program to run the computer controlled stage which is supplied by the stage

manufacturer, and an interpreted BASIC program which drives the system,

acquires the data, provides graphics for a "quick look" at the data, etc.

12
5.1 Nanomovr. This is the compiled program which operates the stage. The

instructions for its operation are given in an earlier section of this

report

There are sixteen different configuration possibilities. These can be

used to drive up to sixteen different motors, a single motor in sixteen

different ways, or any combination. In our case we drive three motors in

five different ways, leaving one configuration possibility unused. The stage

manufacturer calls each configuration option an "axis".

A svimmary of the configuration options as used in this system is shown in

figure 28. Each of the 16 lines in this table, beginning with "X Repeat

Fast," is a brief indication of the motion expected for that particular set

of options. The actual configuration for each line in this table is made by

choosing Change from the menu and selecting the appropriate line from the

table. Figures 29-31 show representatives menus of these options. All the

choices from the table in figure 28 which move the X axis motor are shown in

figures 29-31. The corresponding Y and Z choices are similar, except for

Axis Name, Motor #, and values of Plus Key and Minus Key, The axis names and

motor numbers are all listed in figure 28, and the Plus and Minus Key values

are discussed in the OPERATION section of this report. The stage manual

describes each of the parameters listed in figures 29-31 and how to choose

appropriate values

If the motor parameters are changed, they will be in force only until the

program is terminated unless they are saved in an AXS file. To save parameters, choose the Files option. The parameters shown in the figures are saved in the default file NANOMOVR . AXS . This is the AXS file which is

automatically loaded when the program starts.

The configuration parameters used in the BASIC acquisition program are from lines 11-13 in figure 28, labelled X Tab, Y Tab, and Z Tab. The

acceleration, speed, LM control, and so on used by the BASIC program are from

these parameter tables.

5.2 BASIC Driver Program. This is the program which actually does the data

acquisition. A commented listing of the code written in Interpreted BASIC

for a floppy disk system follows. The code for a hard drive system is very

similar, except for Lines 250 and 5610 (change Hex number to &HD000) , Lines

660, 670 and 1020 (screen parameters) and Lines 1060-1080 which specify the

file name for stored data.

10 'Program CEM which is designed to run the CEM system to measure mode

20 'profiles. It uses the NANOMOVER stage and a PAR 5209 lock-in interfaced

30 'through a CEC-488 card.

40 'Written by Lee Larson, NBS, Boulder, CO 3/15/88

50 ' 60 ' Initialization for NANOMOVER

70 ' 80 DEF SEG=0

9 0 NAN0M0VE=PEEK (320) +PEEK (321)^256

100 NANOSEG=PEEK(322)+PEEK(323)*256

13
110 NANOPOS=PEEK(324)+PEEK(325)*256

120 NANOSTAT=PEEK(326)+PEEK(327)*256

130 DEF SEG

140 'Define 3 axis variables

150 XAX=11 'X axis on front of waveguide (Motor 2)

160 YAX=12 'Y axis on front of waveguide (Motor 3)

170 ZAX=13 'Z axis, focus waveguide (Motor 1)

180 DIM Z%(100,100)

190 'Sub at 5000 (define AXIS, POSITION) moves motor.

200 'Sub at 5200 (define AXIS) reads position into POSITION

210 'Sub at 5400 (define AXIS) reads status into STAT (0 normal w/ no motion)

220 'Sub at 5600 takes a data point; returns value in Q%

230 ' 240 'Initialize CEC board and Lock-in

250 DEF SEG = &HC000

260 INIT=0 ; SEND=9 : ENTER=21 : TRANSMIT=3 : ADDR%=21 : L0CKIN%=9 : LEVEL%=0

270 STATUS%=0

280 Q$=SPACE$(60)

290 LENGTH%=0

300 'LOCKIN ADDRESS SHOULD BE 9 AND TERMINATOR SHOULD BE LF

310 CALL INIT(ADDR%, LEVEL%)

320 DEF SEG

330 ' 340 'Now set up system for measurements

350 CLS

360 PRINT "Stage should be set using NANOMOVR menu for center of waveguide."

370 INPUT "Has this been done (Y,N) ",S$

380 IF S$="Y" OR S$="y" THEN GOTO 430

390 IF S$="N" OR S$="n" THEN GOTO 410

400 PRINT "NOT A VALID ANSWER" :G0T0 360

410 INPUT "Go back to NANOMOVR menu (Y or N) ", S$

420 IF S$="Y" OR S$="y" THEN SYSTEM

430 CLS

440 INPUT "WIDTH OF SCAN IN X DIRECTION (MICRONS) ",WX

450 INPUT "WIDTH OF SCAN IN Y DIRECTION (MICRONS) ",WY

460 INPUT "NUMBER OF POINTS ON EA LINE IN X DIRECTION ",NX

470 INPUT "NUMBER OF POINTS ON EA LINE IN Y DIRECTION ",NY

480 INPUT "TIME CONST OF LOCKIN (MS) ",TCONST

490 DELAY1= TCONST*2/1000 'Delay time is twice time const of lockin

500 INPUT "NUMBER OF READINGS TO SIGNAL AVERAGE ",NOSIG

510 INCX=WX/NX 'INCREMENT TO MOVE IN X DIRECTION

520 INCY=WY/NY 'INCREMENT TO MOVE IN Y DIRECTION

530 INPUT "PRESS <RETURN> KEY TO BEGIN TAKING DATA " , S$

540 GOSUB 5600 'Take peak value before moving

550 ZMAX%=Q% 'Store as initial value for ZMAX%

14
560 SCALE=2*NY/ZMAX% 'Scale factor for data plotting

570 0FFSET=2 'Rot factor for plot; > num plots straighter

580 'MOVE STAGE TO STARTING POINT

590 AXIS=XAX 'X DIRECTION ON FRONT OF WAVEGUIDE

600 P0SITI0N=-NX*INCX/2

610 GOSUB 5000

620 AXIS=YAX

630 P0SITI0N=NY*INCY/2

640 GOSUB 5000

650 CLS

660 SCREEN 2 670 VIEW (0,0)-(719,317)

680 KEY OFF

690 WINDOW (0,0)-((NX+(NY/OFFSET)) , (1 .5*NY+ZMAX%*SCALE))

700 FOR Y=0 TO NY

710 AXIS = XAX

720 POSITION=INCX

730 FOR X=0 TO NX

740 GOSUB 5600 'Get data point

750 Z%(X,Y)=Q%

760 LOCATE 25,1: PRINT Q%

770 IF X=0 THEN PSET (X+Y/OFFSET , Y+Q%*SCALE)

780 LINE -(X+Y/OFFSET,Y+Q%*SCALE)

790 IF Q%>ZMAX% THEN ZMAX%=Q% 'Make sure ZMAX% is largest value

'Don't inc position after last data pt

'Move to next X position

'Don't inc position after last data pt

'Move to next Y position

'Return to beginning X position

800 IF X=NX THEN GOTO 820

810 GOSUB 5000

820 NEXT X

830 IF Y=NY THEN GOTO 870

840 AXIS=YAX

850 P0SITI0N=-INCY

860 GOSUB 5000

870 AXIS=XAX

880 POSITION=-WX

890 GOSUB 5000

900 NEXT Y

910 'Return stages to starting point

920 AXIS=XAX

930 P0SITI0N=NX*INCX/2

940 GOSUB 5000

950 AXIS=YAX

960 P0SITI0N=NY*INCY/2

970 GOSUB 5000

980 LOCATE 25,1: PRINT "PRESS <RETURN> TO CONTINUE";

990 INPUT S$

1000 KEY ON

1010 CLS

1020 SCREEN 0

1030 'Save data in a file

1040 INPUT "SAVE DATA ON DISK (Y,N) ",S$

15
1050 IF S$="N" OR S$="n" THEN GOTO 4990 'End

1060 INPUT "NAME OF FILE (NO EXTENSION OR DRIVE SPECIFIED) ", F$

1070 INPUT "BE SURE DATA DISK IS LOADED IN DRIVE B; PRESS <RETURN> WHEN READY

", S$

1080 F$="B: "+F$+" .GRD"

1090 OPEN F$ FOR OUTPUT AS #1

1100 PRINT #1,"DSAA"

1110 PRINT #1, NX+1,NY+1

1120 PRINT #1, 0,WX

1130 PRINT #1, 0,WY

1140 PRINT #1, 0, ZMAX%

1150 FOR Y=0 TO NY

1160 FOR X=0 TO NX-1

1170 PRINT #1 , Z%(X,Y)

1180 NEXT X

1190 PRINT #1, Z%(NX,Y)

1200 PRINT #1,

1210 NEXT Y

1220 CLOSE #1

1230 PRINT "DATA SAVED IN FILE " ; F$

4990 END

5000 'Subroutine to move position

5010 DEF SEG=NANOSEG

5020 CALL NANOMOVE (AXIS, POSITION)

5030 DEF SEC

5032 GOSUB 5400 'Check STAT; wait for motor to stop moving

5034 IF STATUS AND 1 THEN GOTO 5032

5040 RETURN

5050 ' 5200 'Subroutine to read position

5210 DEF SEG=NANOSEG

5220 CALL NANOPOS ( (AXIS , POSITION)

5230 DEF SEC

5240 RETURN

5250 ' 5400 'Subroutine to read status

5410 'A reading of 0 is when all is normal and there is no motion

5420 DEF SEG=NANOSEG

5430 CALL NANOSTAT(AXIS , STATUS)

5440 DEF SEC

5450 RETURN

5460 ' 5600 'Subroutine to get data point from lockin

5602 START=TIMER

5605 IF (TIMER- START )<DELAY1 GOTO 5605 'Allow for settling time

5610 DEF SEC = &HC000

5612 B=0 'Sum of signals for signal average

5615 FOR S=1 TO NOSIG 'Take NOSIG readings for sig ave 5620 A$="OUT"

16
5630 CALL S END (LOCKIN%,A$, STATUS %)

5640 Q$=SPACE$(60)

5650 CALL ENTER (Q$,LENGTH%,LOCKIN%, STATUS %)

5660 Q=VAL(LEFT$(Q$,LENGTH%)) 'DATA POINT RETU^ED AS Q%

5665 Q=ABS(Q)

5666 B=B+Q

5667 NEXT S

5670 DEF SEG

5675 Q%=INT(B/NOSIG) 'Signal averaged value to return

5680 RETURN

A second BASIC program named CEMBACK is on the NANOMOVR disk. It is

essentially the same as the one shown above, except that the scan starts at

the upper right corner instead of the lower left. The only changes are the

directions to increment and loops which start at the maximum value and work

down rather than starting from the smallest value as is the case with CEM.

6 . References

[1] Young, M. Refracted-Ray Scanning (Refracted Near-Field Scanning) for

Measuring Index Profiles of Optical Fibers, chapter 3 in Optical Fiber

Characterization Nat. Bur. Stand. (U.S.) Spec. Publ. 637, V. 1; 1982

July. 200 p.

[2] McCaughan, Leon; Bergmann, Ernest Index Distribution of Optical

Waveguides from Their Mode Profile. J. Lightwave Technology LT-1:

241-244; 1983 March.

[3] Morishita, Katsumi Index Profiling of Three Dimensional Optical

Waveguides by the Propagation-Mode Near-Field Method. J. Lightwave

Technology LT-4 : 1120- 1 124 ; 1986 August.

[4] Kim, E.M.; Franzen, D.L. Measurement of Near-Field Radiation Patterns

from Optical Fibers, chapter 3 in Optical Fiber Characterization Nat.

Bur. Stand. (U.S.) Spec. Publ. 637, V. 2; 1983 October. 239 p.

17
APPENDIX A

Drawings of Parts

A. Spacer

B. Detector case

C. Mounting plate

D. Optical table

E. Optical table

F. Spacer

G. Bracket assembly

H. Bracket assembly

I . Substrate holder

J . Spacer

K. Mounting plate

18
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APPENDIX B

List of Commercially Available Parts

This list is provided solely for the convenience of the reader who wishes

to duplicate this system exactly. The inclusion of a piece of equipment on

this list does not imply endorsement or recommendation by the National Bureau

of Standards. In many instances alternate pieces of equipment from other

manufacturers would perform well.

{1} TMC #74-119-02 Optical Breadboard

Technical Manufacturing Corp . , 15 Centennial Dr., Peabody, MA 01960

617-532-6330

{2} Melles Griot #05LHP111 Laser with #05LP340-1 Power Supply

Melles Griot, 1770 Kettering St., Irvine, CA 92714 714-261-5600

{3) Newport #806 Mount and #375 Rod/Clamp Assembly

Newport Corp., 18235 Mt. Baldy Circle, Fountain Valley, CA 92708

714-63-9811

{4} Newport #10B20 Beamsplitter, #GM-1B Mount, #VPH-3 Holder, #SP-2 Post,

#BU-P Base

{5} Newport #VPH-4 Holder, #SP-3 Post, #BU-P Base

Centronic #CD-33H Photodiode (2 required)

Centronic Electro-optics, Inc., 1829 B DeHavilland Dr., Newbury Park,

CA 91320 805-499-5902

{6} Stanford Research #SR540 Optical Chopper

Stanford Research Systems, Inc., 460 California Ave., Palo Alto,

CA 94306 415-324-3790

Newport #SP-6 Post, #BU-P Base

{7} Daedal #4416 Positioning Stage

Daedal, Inc., P.O. Box G, Harrison, PA 15636 800-245-6903

(8) Newport #900 Spatial Filter

{9} Newport #LP-05B Mount with #LPMH-05 Adapter (2 sets needed)

(10) Edmund Scientific #G30.047, #G30.048, #G30.049 Microscope Objectives

Edmund Scientific, 101 E. Glouster Pike, Barrington, NJ 08007

609-547-3488

{ll)Melles Griot Nanomover System and Stage consisting of; 3 #11NCM001

Nanomover Positioners, #11NCS001 Advanced System Controller, #11NCN001

Nanomotion Card, 3 #07TSC007 Translation Stages, #07TSB007 Angle

Bracket, #07TSA007 Z Motion Adapter

Melles Griot, 1770 Kettering St., Irvine, CA 92714 714-261-5600

30
{12)Newport #460-XYZ Stage

(13) Edmund Scientific #G30.046 Microscope Objective

{14)Newport #LP-05B Mount with #LPMH-05 Adapter (see {9})

(15) Newport #ID0.5 Iris and Mount Assembly

{16)Newport #MPH-1 Post Holder, #MPS-1.5 Post, #BU-P Base

Centronic #CD-33H Photodiode (see (5))

{ 17 ) EG&G/PAR Model 5209 Lockin Amplifier

EG&G/PAR, Scientific Instruments Div. , P.O. Box 2565, Princeton,

NJ 08543 609-452-2111

{18)Bausch and Lomb SVB-73 Microscope, #31-26-40-73

Bausch and Lomb, Inc., Box 450, Rochester, NY 14692 716-338-6086

31
ot—(j

a>d

bO

Ci^

32

COMPUTER

CONTROLLED

XYZ

STACE
33
34
Amplifier

Housing

o

<DC

35

Figure

4.

Detector

amplifier

schematic.
36

Figure

5.

Data

from

25

/xm

pinhole.
%

e

37

Figure

6.

Data

from

25

/im

pinhole.
o oo (O CM o

00

(O

CMo

oo <0 CM

O

38

Figure

7,

Data

from

single

mode

fiber,

out

of

focus.
LJO

:z<

“I

Q

(O CM

39

Figure

8.

Data

from

single

mode

fiber,

in

focus.
Gaussian

;dlSN31Nl

40

Figure

9.

Vertical

cross

section

of

data

from

single

mode

fiber,

with

Gaussian

fit.
ISOOOn

Expt

A11SN31NI

41

Figure

10.

Horizontal

cross

section

of

data

from

single

mode

fiber,

with

Gaussian

fit.
'**

'nil

'urri ft:

•|j^#=.».l :L

O'.*

K«:i rc:

3*> I

<•jri2:

l*S**Z*»jni ;

CM

O

42

Figure

11.

Mechanical

surface

profile

(top)

and

corresponding

mode

intensity

profile

(bottom)

of

optical

waveguide.
o

o

oro

«CM

«

CM

CM

CM

CM

OCM

2 E

=5. 2uj

o

<

h00

CM

— eo

<o

CM

CM O flO <0 CM O

43

Figure

12.

Mechanical

surface

profile

(top)

and

corresponding

mode

intensity

profile

(bottom)

of

optical

waveguide.
0) T3O

bOC • TJ (U C T) O -H a 13 W bO 0) 0) u > o > o

i-H T) (fl C O

(d -iH iJ

/-V CXi

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Ct,

44
I

<1jI

It:

'-lurii

45

Figure

14.

Mechanical

surface

profile

(top)

and

corresponding

mode

intensity

profile

(bottom)

of

optical

waveguide.
46

Figure

15.

Mechanical

surface

profile

(top)

and

corresponding

mode

intensity

profile

(bottom)

of

optical

waveguide.
47

Figure

16.

Measurement

of

intensity

of

light

from

a

fiber,

as

fiber

end

position

is

changed.

Source

is

He-Ne

laser.
48

Figure

17.

Measurement

of

intensity

of

light

from

a

fiber,

as

fiber

end

position

is

changed.

Source

is

He-Ne

laser.
49

Figure

18.

Measurement

of

intensity

of

light

from

a

fiber,

as

fiber

end

position

is

changed.

Source

is

He-Ne

laser.
—7—'—

7

—^—~r

00t 0Q 09 0^^

A2ISN31NI —

7

02

T)C

0) ti u

OJ bOC

•H •H <w u

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* o

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tfl Vi E 0) o w

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4J CO x:

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CO

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4.) cn C •pH 0)B c

0) o • v '*pH q

d VI q

M •r-4 CO CO o <U O in s p0)d

bO

•l—

I

50
AJ.ISN3J.NI

51

Figure

20.

Measurement

of

intensity

of

light

from

a

fiber,

as

fiber

end

position

is

changed.

Source

is

a

laser

diode

operating

at

750

run

.
T3C

(U 4J

cO

!-i (U bO

XI

C

•r^ •H

4J

CO

w

M

CO 0)a.o

d) 0) Xi T3

•IH o

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T)

COs d) o CO

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iJ CO

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iJ d) C bO

•pH c

CO iwo o

4.) CO c •rH (US c • 0) o s

)-l •rH ^ 3 4J

CO •r4

CO CO

O

(U o m S (X

CM

0)

W)

•H

52
o

r o

m

r

CM

o

q:

LU

QQ

o

Q

<

LU

o

o

-- o

GO

CD

(uurf) yoyy3

53

Figure

22.

Data

from

laser

interferometer

showing

stage

position,

stage

not

moving.
500 rO CM

AON3n03yj

54

ERROR

BETWEEN

READINGS

(jjm)

from

laser

interferometer

showing

stage

position,

stage
E

_j<>

LU

h-oQ<

LJ

cro

CNJ

q:

LU>o

cro

QL

cr

LU co

•r-l iJuoa

(VbO

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I/l bOC3oX

COu0) u0) Eou0) C4-I u

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0)

cn >

(0 o

r-l

B e iJ o o u c

Cm 0) <0 60 M ra

CQ

M

a CO

jCNJ

(Vkl3

bO

u.

A0N3n03dJ

55

400

CD

O

ho

vOCM

0)

I.J 3

bO

U.

T

1 r o O

o

ro CM

A0N3n03dJ

57

ERROR

BETWEEN

SINGLE

STEPS

(pm)
A0N3n03yj

58

ERROR

OVER

20

MICROMETER

INTERVAL

(pm)
=Nanomotion System:

Welcome to the Melles Griot Nanomotion System

Copyright 1986» 1907 Melles Griot, All Rights Reserved

Nanomover software version 1.1

Turn the Nanoamp Chassis POWER switch ON

Press any key when done

Move Change

Move motors

Program Files Setup Quit

Axis Motor Position Units Motion

X Repeat Fast 2 8,771.200 microns Repeat

Y Repeat Fast 3 12,029.799 microns Repeat

z Repeat Fast 1 12,512.000 microns Repeat

X Repeat Med 2 0,771.200 microns Repeat

Y Repeat Med 3 12,029.799 microns Repeat

z Repeat Med 1 12,512.000 microns Repeat

z Jog 1 12.512 000 mm Jog

X Repeat Slow 2 8,771.200 microns Repeat

Y Repeat Slow 3 12,029.799 microns Repeat

z Repeat Slow 1 12,512.000 microns Repeat

X Tab 2 8,771.200 microns Tab

Y Tab 3 12,029.799 microns Tab

z Tab 1 12,512.000 microns Tab

X Absolute 2 8,771.200 microns Absolute

Y Absolute 3 12,029.799 microns Absolute

z Absolute 1 12,512.000 microns Absolute

59

Figure

28.

Nanomover

configuration

options.
f'J

tsj

Edit Copy Quit

Use Return to select axis to edit

d^anomover Parameters:

Axis

Repeat Fast

Repeat Fast

Repeat Fast

Repeat Med

Repeat Med

Repeat Med

Joq

Repeat Slow

jjType new value* arrow keys to move* ESC to exit

II X Repeat Fast

jjAxis Name: X Repeat Fast

IjMotion Type: Repeat

II Base velocity: 62.500

||Lost Motion: Disabled LM

IIijAccel: 200,000.000 0

||Vel: 3,000.000 0

Position: 8,771.200

Motor H: 2 Units: microns

Plus Key: W Minus Key: Q

Position Lock Time: 10

Direction: LM Value: 1

Repeat Slow jjunits to move: 10.000'

0

0

Home Position: 0

Repeat

Tab

Tab

Slow ||Absolute LStop: 0 Absolute RStop:

=Re 1 a t i V e^====

25,000.000

Tab

Absolute

Absolute

Absolute

jjLeft Stop: 0

II TABS:

IP

IP

IP

IP

Rt. Stop: 25,000.000

0

0

0

0

Edit Copy Quit

Use Return to select axis to edit

Axis

X Repeat Fast

Y Repeat Fast

Z Repeat Fast

X Repeat Med

Y Repeat Med

Z Repeat Med

Z Joq

X Repeat Slow

iNanomover Parameters: li||Type new value, arrow keys to move, ESC to exit

II X Repeat Med

jjAxis Name: X Repeat Med

jjMotion Type: Repeat

||Base velocity: 62.500

IjLost Motion: Disabled

:cel: 200,000.000 0

Pl> 3,000.000 0

Position: 0,771. 200

Motor #: 2 Units: microns

Plus Key: S Minus Key: A

Position Lock Time: 10

LM Direction: LM Value: 2

Y Repeat Slow

Repeat Slow

Tab

Tab

Tab

Absolute

Absolute

Absolute

lits to Move: 1.000

j Absolute LStop: 0

jjLeft Stop: 0

11 TABS:

IP

IP 0

IP 0

IP 0

Home Position: 0

Absolute RStop:

n»i

25,000.000

Rt. Stop: 25,000.000

0

0

0

0

60

Figure

29.

Nanomover

configuration

options.
Edit Copy Quit

Use Return to select axis to edit

Ax I s

X Repeat Fast

y Repeat Fast

•7 Repeat Fast

X Repeat Med

Y Repeat Med

Z Repeat Med

2 Joq

X Repeat Slow

y Repeat Slow

Z Repeat Slow

T ab

Tab

Z Tab

X Absolute

y Absolute

Z Absolute

^ iMannm

lIType new value, arrow keys

aver parameters —

to move, ESC to exit *

:l

11

II X Repeat Slow

II Position: 8,771.200

j|Axis Marne: X Repeat Slow Motor i; 2 Units: microns

||Motion Type: Repeat Plus Key: X Minus Key; Z

11 ||Base velocity: 62.500 Position Lock Time; 10

!1 ||Lost Motion: Enabled LM Direction: - LM Value: 2

II

II

II Accel; 200,000.000 0 0 0

II

11 ||Vel: 500.000 0 0 0 1ll

II||Units to move; 0.100 Home Position: 0

II

||Absolute LStop: 0 Absolute RStoo; 25,000.000 —Pe 1 a t i VP . — - II

II

'

IIj|Left Stop: 0 Rt. Stop: 25,000.000

11

II

11

II TABS:

11 ||0 0 0 0

1|0 0 0 0

||0 0 0 0

II ||0 0 0 0

II =!J

Edit CoDV

Use Return to

Quit

select axis to edit

Axis

Joq

Tab

Tab

Z Tab

X Absolute

Y Absolute

Z Absolute

fr iJJanomover Parameters:

» Fast

jjType new value

II Fast II Fast

II Ax is Name: X Med j|Motion Type:

Med

|{Base velocity:

IjLost Motion: 1 Med

1 Slow

jAccel: 100,000

jVel: 500.000

SlOM |Units to move:

Slow ^Absolute LStop

X Tab

Position: 9.771.200

Motor i: 3 Units; microns

Plus Key: I Minus Key; U

Position Lock Time: 10

LM Direction: - LM Value: 2

)0 0

0

0.050

jjLeft.Stoo: 0

II TABS:

||0 0

110 0

||0 0

|j0 6,000.000

Home Position; 0

Absolute RStoo: 25,000.000

=R>lati yg

Rt. stop: 25,000.000

0

0

0

12,000.000

0

0

0

10,000.000

61

Figure

30.

Nanomover

configuration

options.
rsi ig

Edit Copy Quit

Use Return to select axis to edit

Axis

X Repeat Fast

Y Repeat Fast

Z Repeat Fast

X Repeat Med

Y Repeat Med

Repeat Med

Joq

X Repeat Slow

Y Repeat Slow

Z Repeat Slow

X Tab

Y Tab

Z Tab

X Absolute

Y Absolute

Z Absolute

li" =Nanomover Parameters;

Type new value* arrow Weys to move* ESC to exit

X Absolute

Axis Name: X Absolute

Motion Type: Absolute

Base velocity: 62.500

Lost Motion: Enabled

Accel: 100,000.000 0

Vel: 2,000.000 0

Units to move:

Absolute LStop:

0.050

Left Stop;

TABS:

0

0

0

0

0

0

0

0

Position: 8*771.200

Motor #: 2 Units: microns

Plus Key: 4 Minus Key: 3

Position Lock Time: 10

LM Direction: - LM Value: 2

0

0

Home Position; 8*000.000

Absolute RStop: 25*000.000

iJ^elative

Rt. Stop: 25*000.000

0

0

0

0

0

0

0

0

System:

II

II

Melles Griot Nanomotion System

Proqram Terminated

Haye A Nice Day'

n

»

IIL

62

Fieure

31.

Nanomover

conf

ieuration

options.
U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1, PUBLICATION OR

REPORT NO.

NBSIR 88-3092

2. Performing Organ. Report No. 3. PubI ication uate

August 1988

4. TITLE and subtitle

System for Measuring Optical Waveguide Intensity Profiles

5. AUTHOR(S)

Lee E. Larson, Donald R. Larson, Robert J. Phelan, Jr.

6. PERFORMING ORGANIZATION (If joint or other than NBS. see instructions) 7. Contract/Grant No.

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered

WASHINGTON, D.C. 20234

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

10, SUPPLEMENTARY NOTES

I I Document describes a computer program; SF-185, FIPS Software Summary, is attached,

11, ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

We have developed a computer controlled system to measure the intensity

profile of optical waveguides. Knowledge of the intensity profile provides

an indication of the shape of the waveguide, and therefore the degree to which

light can be coupled to the guide from an optical fiber. This report

describes the construction and operation of this system.

12, KEY WORDS (S/x to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons

computer control; coupling; mode intensity profile; optical fiber; optical waveguid

13, AVAILABILITY

I X I Uni imited

I I For Official Distribution. Do Not Release to NTIS

I I Order From Superintendent of Documents, U.S. Government Printing Office. Washington, D.C.

20402.

14. NO. OF

PR.NTED PAi.

68

15. Pr

Order From National Technical Information Service (NTIS), Springfield, VA. 22161

i

*U.S. GOVERNMENT PRINTING OFFICE: 1 9 8 8-0-6 7 3-4 6 3/S 00 3
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