... A Moiré Story

Iota Theta Eta Kappa Gamma Beta Alpha Delta Epsilon Zeta

As first mentioned in The Basics-Part 2, we see a different moiré pattern and/or configuration in each of Wah's ten communicators:











Though to simplify the matter, all but three were derived from only two separate original images; a painting called "Fall" and Edmund Scientific's "Pattern #4."  This is how it all came together.

Pattern #4 - The "Spider" Moiré

Dr. Gerald Oster (at far right, here w/ Salvador Dali), renowned bio-physicist and mathematician then with Brooklyn’s Polytechnic Institute, co-wrote a May 1963 Scientific American article on the optical effects of moiré patterns - the strange and interesting lines generated from overlaying two similar images atop one another.  In an effort to make his work more accessible, he then teamed up with Edmund Scientific Co. to create a whole range of moiré products and educational materials for mainstream consumption.

Their initial offering, first listed in the 1965 catalog on Page 74...

(link to higher resolution image of Page 74 for easier reading)

... was a "Student's and Experimenter's Moiré Kit" and similar "Educator's and Designer's Moiré Kit" (with thicker stock) of eight small patterns (3¾" x 4½" transparencies with matching cards).  This first kit was called their "Series (A)":

It also came with a reference book discussed more in detail below.  Of the eight moiré patterns Dr. Oster first created, the one that seems to have caught Wah Chang's eye was Pattern #4 ("Radial Lines"), which when rotated atop another creates a fun "spider" effect of expanding and contracting arcs.  When turned by a 30-second stopwatch, this became the dynamic effect in his two hero communicators.  The image below is of an actual transparency & card; the red lettering is our:

The distance the stacked images are offset influences the resulting moiré arc lines.  Here with Pattern #4, observe that the closer the two centers are, the fewer but thicker are the lines, and the closer to the center the arcs can still be distinctly seen:

The second (1/8") and the fourth (1/32") pics above are pretty much what we see in Alpha (averaging 0.118" apart) and Beta (averaging 0.023" apart), respectively:

Another difference arises based on how you assemble the two layers.  If you locate the center of the bottom (turning) layer well off the stopwatch's axis but the top (motionless) transparent layer is on-center, the arcs will grow and shrink, plus the entire spider pattern will rotate at the same speed and direction as the stopwatch.  In essence you get two motion effects for the price of one!  This is what we see in Alpha.  If, however, the positions are reversed, such that the bottom layer is on-center and the top is off-center, the growing / shrinking arc patterns will stay pretty much fixed in the same orientation   This is what happens in Beta.

This difference can be confirmed by drawing a line through the arc axis of both.  In "Friday's Child," Alpha's pattern rotates in the 4.5 second total clip about the expected 54 degrees.  In Beta's only close-up, in "Day of the Dove," during about 2.5 seconds (starting while the camera is still zooming in) we would expect 30 degrees of rotation if it was built identical to Alpha, but instead there's barely any:

Alpha beginning:    ending:         Beta beginning:    ending:

It's fun to note if both top and bottom layers are off-center, the arc patterns will transition from a "slow & many-arcs" pattern like in Alpha to a "fast & few-arcs" pattern like in Beta, and back again.  We actually see this happening in the large moiré display at Spock's bridge station:

*   *   *   *   *   *

With the #4 pattern established as his hero model, Wah looks to have scrounged for extra similar images to put in some of his eight static dummies, so he turned to a related source.  To accompany Edmund Scientific's moiré kit, Dr. Oster  also wrote a short technical guide book called “The Science of Moiré Patterns,” copyrighted 1964 and selling for $2 at the time:

front    back

The pink seen on the cover of this first (1964) edition is on a plastic overlay held on by the bright red "report" clip on the bound edge.  All pages of this 8.5"x11" book are reproduced at the bottom of this page for your studying pleasure.

On its Page 9 we see a number of moiré patterns reproduced.  The #4, while much more crude here on rough paper stock than on the smooth Kromokote in the kits, was nonetheless cut out and installed in Epsilon.  Note the asymmetric blank patch surrounding the black dot in the center that confirms for us the exact source and also its rotational orientation in the prop:

Wah next cut out the Pattern #4 "spider" image from a loose-sheet advertising insert (a reprinting of a combined Page 38 and 74 from the Edmund Scientific catalog) that came along with the 1964 moiré book - and put it into Kappa:

*   *   *   *   *   *

Starting in 1966, Edmund sold an expanded line of Dr. Oster's moiré product kits which included extra moiré patterns, some in larger image sizes and colors.  This 1966 catalog had the exact same Page 74 as the 1965.  It also had the "spider" on the cover, but that one is too large to match what went into Kappa:

(link to higher resolution image of Page 140 for easier reading)

It seems Wah wanted more variety beyond the #4, so he switched over to another pattern for three other comms.

Fall - The "Wavy" Moiré

We begin this part of our tale in 1963 with world-famous British abstract artist Bridget Riley (right), who that year painted amongst other eye-twisting geometric pictures a large 55 in. x 55 in. canvas she named "Fall" - now hanging in the the Tate Britain Museum in London:


A year later, the afore-mentioned Dr. Oster observed the retinal-scrambling properties of Ms. Riley's work.  To accompany his own patterns in his first (1964) edition of “The Science of Moiré Patterns” book, he printed her piece on the front and back covers, plus on Page 24.

Each of the three "Fall" images (cover, Page 24, and back) is at a different scale, which allows us - by matching wavy lines seen in screen caps and other photographs - to determine exactly which ones Mr. Chang used.  Even more specifically, since “Fall” was hand-painted, slight variations in line widths allow us to identify the precise location within that image they were cut from!  So from the version appearing on Dr. Oster's book cover, Wah cut two circles (using an old-fashion radial compass that poked a hole at the center) and inserted them into Delta and Iota:

Delta is self-explanatory; the wavy lines in modern photos of the prop being an absolute perfect match to the moiré book cover.  For Iota we must use a slightly less-precise method.  Its individual wavy lines can't be seen, but the pattern can still be located by observing the secondary "bunching lines" formed from the linear clumping when the waves are tightly spaced.  These larger lines have their own spacing to each other, plus have lighter and darker patches within them, that allow us to get within hopefully a millimeter or so of the actual center.

Another easy one... from Page 24 Wah cut a circle for Gamma, and the great TMOST photo plate allows us again to zero in on the exact location:

Regarding the "why" of this wavy pattern, we can only surmise that Wah found the lines reminiscent of an oscilloscope.  However, we'll never know why he chose those exact spots from two different "Fall" images, especially when one of them had lines so thin (Delta's and Iota's) that the pattern could never be seen on TV sets of the day.  In fact, only once in just one episode, in Assignment: Earth (r >>), were the individual lines in a wavy pattern (Gamma's) at all obvious.

Moving on from the wavy patterns...

Non-descript uniform Concentric Circles for Zeta's Moiré

For Zeta he oddly plucked the Pattern #5 (a boring evenly-spaced 34 lines per 1/2" radius) from the same Page 9 that he sourced Epsilon's pattern from.  It's a blessing that this particular dummy comm survived, as there's no way we'd ever know what its pattern was from just screencaps:

This concentric circle pattern is duplicated nearly exactly on the front book cover as well, but the quality of the print there (the cover having a rougher surface) tells us with near certainty the source for Zeta is Page 9.  Now, when you view the back of that bezel ring (>>), it looks like Wah cut the circle too small and glued it to larger disk from what was likely a manila folder to secure it in the ring.  It is not known if all other dummies had a backing layer, but we guess not.

Note that Zeta's moiré bezel is now loose from the shell, so the original orientation is not known (unless Mr. Jein took a photo that we've never seen of the prop prior to his dismantling it).  That didn't stop us from making a guess, and based on a crude matching of glue spots on the ring vs. what's left on the shell, we show an off-angle orientation in our simulation at the top of this page and in the print-ready 1200 dpi version.

A "Gun Barrel" Spiral for Eta's Moiré

Like with Zeta, Eta got almost no airtime whatsoever.  Just a few hard-found distant glimpses inside are all we've got to go on:

Still, that white spot in the center of its moiré image is so unique that, given its size, it could only have come from one source within the pantheon of Edmund Scientific products:  the Pattern #18 (called a "30-line logarithmic spiral) printed on glossy Kromokote cardstock from their second, lesser-known "Series (B)" kit of Patterns #11 thru 18:


A Wildly Different 2-Layer Moiré for Theta

Lastly there's Theta, and for the longest time its moiré area stumped us utterly.  Sometimes it looks completely black:

Other times it's a very light grey:

And notice how in every case, it's essentially featureless.  It took all we had and a whole lot of dumb luck to unravel this mystery (that's told at great length on Theta's details page), but here we'll just cut to the chase...

This prop had during the show two different inserts, and both were completely unusual.  Wah first installed in the comm a newly-available novel moiré effect that came from two stacked samples of a thin multi-prismatic sheet made by Rowlux that were included in the Edmund Scientific "Experimenter's Moiré Kit with Booklet":

Individually these sheets are unremarkable, but depending on their position against each other they can display an amazing range of various cells, dots, lines and swaths of bright/dark, while also often offering random sparkles as you move it around under light:

Undoubtedly impressed with the material, Wah cut two 1-inch diameter circles out of the sheets, stacked and (presumably) oriented them to look cool, glued them together (with the glue not quite reaching the full perimeter) and installed the assembly in Theta's bezel ring:

The only thing that can't be known with any confidence is what the exact original pattern looked like, as the limited images we have of the spot lack that level of firm detail.

Then.... a year later, sometime before or during the shooting of the "Bread and Circuses" jail fight scene, the bezel ring came off and these sheets fell out.  Upon hasty repairs, what was reinserted was some kind of matte black disk that either was freshly cut from (maybe) construction paper, or perhaps we're seeing the backing of Wah's initial multi-layer installation, and the repair guy in 1967 just put the assembly back in upside-down using an excess of glue:

*   *   *   *   *   *

It will be an enduring mystery why Wah didn't use more of the transparencies and cards that came in the multiple moiré pattern kits he must have had.  After all, some of those pattern combinations create awesome effects even when not being rotated, and the shiny top surface would at least have matched his heroes.  We have to figure he simply had too little time, so after the complexity of Theta he must have went for convenience and just used a single paper layer in the rest.


All Pages of the 1964 "The Science of Moiré Patterns" Book

For those who wish to explore further the actual book Wah used as the pattern source for six of the static dummy communicators, we provide the following scans of all twenty eight pages, plus the outside and inside of both front and back covers as well as the advertising insert (for Kappa's pattern), at 150 dpi resolution.  Wah cut out circles from the front cover (for Delta and Iota), from Page 9 (Epsilon and Zeta) and from Page 24 (Gamma).  Those page names are highlighted in red for a quick find.

Front Cover outside

Front Cover inside (blank)

Page 3

Page 4

Page 5

Page 6

Page 7

Page 8

Page 9

Page 10

Page 11

Page 12

Page 13

Page 14

Page 15

Page 16

Page 17

Page 18

Page 19

Page 20

Page 21

Page 22

Page 23

Page 24

Page 25

Page 26

Page 27

Page 28

Page 29

Page 30

Back Cover inside

Back Cover outside


Advertising Insert (front)

Advertising Insert (back)
All Cards from the original "Series (A)" Edmund Scientific Co. "Experimenter's Moiré Kit"

Sold in the mid 1960s alongside the above moiré science book, and then utilized by Wah in his two hero communicators (Alpha and Beta) plus in one of his two tricorders, was the Moiré Experimenter's Kit - Deluxe.  Those kits that had Patterns #1 through #8 were called their "Series (A)."  It contained eight 4½" x 3¾" Kromokote (a museum-grade semi-gloss white stock) cards, each with a different pattern and a matching transparency.  The description in quotes is what Edmund named each.  We have provided here scans of all eight cards at 300 dpi resolution.  The "Deluxe" version of the kit had thicker transparencies (0.020") than the standard version (0.005"), plus slightly heavier cardstock.

Pattern No. 1
"Coarse grating"

Pattern No. 2
"65-line grating"

Pattern No. 3
"Logarithmic scale grating"

Pattern No. 4
"Radial lines 5º"

Pattern No. 5
"Equispaced circles"

Pattern No. 6
"Fresnel zone plate"

Pattern No. 7
"Sphere projection"

Pattern No. 8
"Cylinder projection"
All Cards from the "Series (B)" Edmund Scientific Co. "Experiment's Moiré Kit"

Starting the following year (in 1966) came the "Series (B)" kit with Patterns #11 through #18.  Wah almost assuredly used the #18 in Eta, but no other patterns from here got put in any other comm.  By the way, Edmunds did not print a "Pattern #9" or "10."

Pattern No. 11
"Coarse sines"

Pattern No. 12
"65-line sines"

Pattern No. 13
"Perspective squares"

Pattern No. 14
"Medium grating"

Pattern No. 15
"Gaussian grating"

Pattern No. 16
"Converging circles"

Pattern No. 17
"Elliptical zone plate"

Pattern No. 18
"30-line logarithmic spiral"


Some Cautionary Notes about Sourcing

Two subsequent editions of Dr. Oster's book, from 1965 and 1969, are of limited or no use to us...

The 1965 and identical 1966 versions, which have a grey printed plastic overlay above the cover instead of pink, does not have the "Fall" image on the cover (the only differences between the 1964 and the 1965 editions), and thus is missing the patterns for Delta and Iota:

The completely revised 1969 version, with a full-color front cover, has no authentic images or transparancies left in it.

Printing Your Own Patterns!
Downloadable 1200 dpi images of all actual patterns used can be found on the Parts and Plans page for the Moiré and Moiré Bezel. moi

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