ULTRAVIOLET FLUORESCENCE PHOTOGRAPHY OF THE SHROUD OF TURIN

V. DMiller and S. F. Pellicori


One of the nondestructive techniques used to investigate the Shroud of Turin was ultraviolet fluorescence (UV) photography. This technique is able to detect organic and inorganic compounds by their integrated emission spectra and it is the complement of the more common technique of reflectance photography. Photographic data collection was one of many information resources designated by the Shroud of Turin Research Project(STURP) team for the investigation of the body image and blood stains. The goal of the team was to determine the nature of the body image and its cause.


Background
The investigation in October 1978 followed the conclusion of the public exhibition held in celebration of the 400th anniversary of the Shroud’s housing in Turin, Italy. That was the first public exhibition in 45 years and the first fullscale multidisciplinary study in the Shroud’s history.2,3

The Shroud is a 4.4 by 1.1 meter piece of age-yellowed linen which displays the life-sized dorsal and frontal images of man. The appearance of the visible image and the locations of the blood stains suggest parallels with the descriptions of Christ’s crucifixion in the Scriptures. For this reason, the legend associated with the Shroud of Turin is that it is the burial cloth ofJesus of Nazareth. It has also been suggested that the image was painted in the 14th century. Since the historical record is complete back only to the 1350’s, the veracity of the legend cannot be directly addressed. Obvious scorch and water marks can be pinpointed to fire in 1532. Hypotheses such as artistic painting, for example, can be tested for agreement with the observations. The team was thus charged with the task of collecting multifaceted data of necessary and sufficient quality and quantity for testing various hypotheses.


The 
United States team, an independent group of 32 scientists and assistants, waequipped with instrumentation4 capable of detecting work produced by known artistic techniques and adequate to provide a broadly-based foundation of information. The instrumentation included xray transmission and fluorescenceto detect high atomic
number elements expected for inorganic 
pigments, microscopy6 for visual and
photographic examination of details, photoelectric spectrophotometry7,8 for measurements of reflectance and fluorescence, photographythrough bandpass filters, infrared spectrometry10 and UV fluorescence photography documented here for the first time.

Image5

Image6

Image7

Image8

Figure 1A–   Transmittance curves for the ultraviolet (UV) exciting filter cell used in front of the xenon source and for the UV barrier filter used over the camera lens.
B–    Configuration of exciter and barrier filters for ultraviolet fluorescence photographyThe exciter filter consisted of a Pyrex window and a filter cell containing a 1 cm path of the solution shown and a Corning 7-54 glass filter for absorption of the residual red leakThe Hoya L-42 filter served as a barrier filter transmitting only those wavelengths above 420 nm. C–   Exciter filter cell attached to flash reflector.

Image9

Figure 2-Camera and Illumination positioned on support rail for indexing along the length of the Shroud and thus creating a complete mosaic of photographs according to the reference layout in Figure 3. A– Lamp heads (Norman 200 B) with liquid cell filter.    -AC power pack. EL Hasselblad camera with 70 mm back-Telescoping extention rod for locating rail equi-distant from Shroud frame. Leveling screws.
-Centimeter scale with indexing marked for predetermined positions. -Adjustable sliding index pointer for starting sequence.

Photographic procedure
To record the emission excited by ultraviolet, a special light source was assembled. For our experiment a filterwindow bandpass enabled wavelengths of 335 to 375 nm to be isolated from the sources for the exciting radiation. The two sources aimed at 45degree angles from the camera-subject axis were 200 watt second xenon strobes with 15-cm reflectors. The film was to record only radiation emitted in the visiblregion of the spectrum, and none of the reflected, exciting UV. Consequently, the light source had to
be free of visible radiation. To achieve these conditions special excitation filters were constructed to fit othe 15-cm diameter strobe sources.
The filters consisted of a 1-cm path length containing mixture of inorganic salts of transition metals 11 to absorb radiation above about 400 nm. One window of the liquid filtecell was Corning 9863 visible-absorbing UVtransmitting glass.
This 9863 filte
was required to attenuate small red leak in the excitefilter. The othewindow was pyrex. The isolated passband and out-of-band attenuation measured for the filter are shown in Figure 1. Since the fluorescences we sought were expected to be in the visible, the filter needed to attenuate to a level of 10– since visible light from the xenon tubes would completely swamthe weak fluorescent signals. The reasons for using liquid filter system were that no other filters such as multilayer coatings or ultraviolet transmission glass alone are able to define the required passband while possessing adequate rejection. Further, none of the standard filter materials could survivthe heat of the xenon flash. Finally, the 15-cm size was beyond standard UV accessories.


The exciting UV energy which was partially reflected by the Shroud was prevented from reachinthe film by nonfluorescing, long-wavelength pass, UV absorbing glass placed in front of the lens (Figure 1). This barrier filter passed wavelengths greater than 410 nanometers.
The 
camera and light source assembly was moved along a rail parallel to the long dimension of the Shroud, which was mounted with its short dimension vertical (Figure 2). The long dimension was divided into eight 53.3-cm square areas for photography and later full-size reconstructionThe areas were intended to be coincident with the blackandwhite coloseparation series taken at another time.
The sections 
were numbered from left to right, beginninat the dorsal feet end of the Shroud. The number-letter coordinate set corresponded with master reference mosaic and is shown in Figure 3.
The camera was Hassleblad EL with a 80 mm lens. The film used was Kodacolo400 film, a color negative film with an exposure index of 400. Prints were then made on Kodak Ektacolor no. 78 paper.
Differences between 
the fluorescent record and white light photos were noted.
Assisted by laboratory data
interpretation of these differenceprovides insight into the nature and causes of the various markings on the Shroud, namely the body image, blood stains, and scourge, wateand scorcmarks. These interpretations can be compared with laboratory-produced simulations.


Detailed observations
Some general comparisons from color photographs of fluorescing colors and natural light colors are listed in Table I.
Differences are detailed in the following pages for each section of the Shroud under discussion. Section through by 1 through 4, for exampledefines a rectangle according to the coordinates of the reference overlay on the Shroud. (See Figure 3 and the reduced size overlay in the text.)
Image10Figure 3-Reference layout of the Shroud showing the numbered and lettered sections discussed in detail in the text.

Table I-Comparison between UV Fluorescence and Visible Reflectance Photographs
Image11

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Figure 4– Section B through Eby throug4 of the Shroud. A-UV fluorescenceB-white light reflectance photograph.

Dorsal feet area– through bthrough 4 (Figur4)
Some cloth fluorescent characteristics stand out as different from the white light appearance, namely creasesthread, and shadowing arless apparent in UV.
The striation in the weave pattern (warp versuweft) are enhanced in fluorescence.
Theris a general decrease in cloth emission at the corners. The teflon coated magnets, quite visible in white light, are nonfluorescent. This signifies threjection level of reflected lightThe visual water markare nodetectible fluorescently, while the scorches around the burns emit reddish fluorescence.
Left foot-C through D b1 through 2
Blood ired visuallybut neutral to black (absorbingfluorescently. Detailed shading in absorption in the blood in center of left foot. triangular-shaped pattern is seen at the ball of the foot. Note the very dense absorption in the blood area at the left end of the rivulet from the heel: scorching might be associated. A fluorescing border in the blood now off the body image areas is seen.
Right foot
A more distinct light border area iseen. The body image appears differenfrom thblood in fluorescencethat is, iabsorbs less intensely. The scourge marks have greater contrast in fluorescence than in white light and on the calf appear as linerather than as dumbbell shapes as they do furtheup on the leg. Some scourges arnot perceptiblin the white light photo. The scourge Linerun parallel and diagonally from top left to bottom right. T hbackground clotfluorescence is prominent between the leg image(C-D area). The absorbing water marks at and B through E have Lighborder areas.

General dorsal areas– 4 throug(Figure 5)

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Figure 5– Section through E by through 6A-UV fluorescence-white light reflectance photograph.

Red fluorescence is seearound patches at left and right boundries.
There is a 
series of holes through t he Shroud cloth (through which threinforcinbackincloth sewn to the Shroud after the fire can be seen). The densely burned borderof these burned holes show no emission. Where the morlightly scorched material matches the appearance of other scorched areas (around added patchesfor example)the fluorescent appearance is quite differentthat is, no emission is seenThe different appearances might relate to different generation mechanisms.
Calf areas of right and left leg Scourges favor orthogonal orientation in this area. As the thigh is approachedthe scourges become scratchlike. On thright leg at C-5 and D-6, the scourges appear to be off the body image area. Weave striations are obvious in fluorescence. ID-6 and C-6, we note small areas of brightness betweecenteburns in botem ission and reflectiophotos. The circular mark in the thighs (D-5 and C-5) resembling a scourge might be scorch mark. Similarly, in D-7 and C-7, there is nfluorescence emission, but perhapthe marks have the same origin as the circular burn holes in this section.
At the boundaries, Band E, and a round the patches, the scorches display shading in red emission. These scorches appeadifferent from thburn holes. The water stainC-5 and D-5, did not disturb thscourge marks. Iareas hrougE by 6-7, faint red-brown bandare apparent: they traverse the burn holes. Notice at the expected knee joint, 6that there inbody image apparent and limited scourging.

Image14

Figure 6– Section through E by through 9A-UV fluorescenceB-white light reflectance photograph.

Dorsamidsection area– 7 throug9 (Figure 6)
All the patched burn areas fluoresce reddish brown, including the water stain front. Other white light water boundaries are indistinguishable in fluorescence. The scourges orient orthogonally and are distinctly absorbent against the fluorescent background linen. The emission of the linen is not uniform. Across the small of the back the rivulets of blood are absorbing; see also D-9 and C-9. There aresome lighter border areas associated with the blood flow. Some of the densest marks within the blood flow area might be scorches. In area D-8, the blood boundaries fade in fluorescence. At E-8 and C-8 the stainat the inner boundary of the large patches appear to be mirror images.
Two 
small circular stains at C-7 and D7 are mirror images and visualiy resemble weak scorches. In fluorescence these stains are absorbing. Note also lighter boundary areas associated with water marks. The body image (nonfluorescing) is very dense at the scapula and rib cage.
Scourges 
are apparent through the scorched shoulder areas above the patches. Many scourges have fluorescing bordering areas.

Image15
Dorsal head and neck area and ventral head area– 10 through 12 by B through E (Figure 7)

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Figure 7– Section B through E by 10 through 12A-UV fluorescence. B-white light reflectance photograph.

At E and Band at patches 11 and 12, red fluorescing scorched areas are obvious. The brightly fluorescing yellowgreen donut-shaped areas to the right of patch 11– 12 at E and B appear to be scorchesThey are mirrored elsewhere at symmetrically located fold sections. The faint water stain between the head images has lighblue boundaries in fluorescence. The cloth weave striation is an apparent nonuniformity. The blood stains on the dorsal head area are bounded by brighter areas. A smudge or scourge appears to the right of the general blood flow on the dorsal head. Faintscorch pattern is visible in the light blood stains. At C-D by 11-12 smudge resembling blood is visible between the head imagesThe dorsal body image is more distinct than the ventral image. At the center of the dorsal head, a blue fluorescence is noted. This has a different color than the body image.

Image17

Figure 8– Section B through E by 13 through 15. A– UV fluorescenceB-white light reflectance photograph.

Heaand chest-13 through 15 bthrough (Figure 8)
Scorches near thpatches emireddish brown fluorescence. Thwatestain boundarbelow patches at C15 anE15 appeato contain reddisfluorescenmateriaas froscorcheswhile those at C and D at 15 (abdomendnot contain fluorescing material. Thlower left arm bloostains, and C at 16, have lighborder areas. Througthe scorches of B a14 and 15, upper left armcan be seen bloooscourges. Thupper area of thleft shoulder shows fainblood, scourge and boddetail. Thdiffusely appearing
sco
urge markbelothe centrawatestain, C and D at 16, becommordistinct
(sc
ratch-like) neaC15 and D15. Scourges ardiagonaand orthogonalwith a scratccharacteristipredominant othleft. Thface imore strongl bounded by thweave pattern on its left side thaon its right, C and D at 13. Goinbeyond thifeature, nimage idiscernible. Thbloostreakin thhair ardenseothright side and have fluorescinboundaries, C and D at 13. In comparison with the generabodimage, thbeard and mustache ardenserln fact, thdensitis greatest othlefportioothe beard and mustache anmore diffuse othright. A distinct boundaris present at thloweleft. Thlower lip appears to have a fluorescenboundary. On thright shoulder, thbloostains arin very sharp detailwitthlower stain broken into dotsCompare
t
hiarea witsome othe scourges othright sideCircles oyellowgreen fluorescence are associatewitthese wounds.

Image18

Figur9 Section B through E by 16 throug19. A-UV fluorescenceB-white light reflectance photograph.

Ventral hands and thighsarea 16 through 1(Figur9)
Scorches show red fluorescence except for those associated with the sets of three holes which have heavily burned borders. Plumes of pyrolyzed materials pointing toward the feet are seen associated with the burned holes. At 19 the plume pointing toward the hands fluoresces red. Some shading from red to yellow fluorescence can be seen. The water mark above the knees at 18 has an absorbant edge with density gradations.
Some fluorescing bordering can be seen also. In white light, however, this water stain is not prominent. The fluorescent color is brown as opposed to grey. The water stain situated above the series of holes to the right side has very little emission. Some of the water stains are better defined in fluorescence, others are not. The blood and body image are similar in the fluorescence photos; i.e., grey and non-emitting. Notice the clear fluorescing borders around the hand wound blood stains. As is true of scourges elsewhere, the scourge wounds are more distinguishable in the fluorescence photos. As the uppethigh area is approached, however (see 19), the scourges become more diffuse. Often scratches are contained within the diffuse areas. Some scourge marks appear only in the fluorescence photos: examples are noted between the hands and forearm areas.
Around 
the knuckle of the left hand a slight blood flow can be seen. The body image absorption, especially arm anthigh, is greater on the left side of the body. There is detail located where the genitals would be expected below the intersection of the handsThe dark patch below the wrist wound appears distinct from the body image. It is not understood. The fingers possess more contrast by fluorescence photographyThe differences among water stain appearances might be due to differing material content, with some containing mobile pyrolysiproducts.

Image19

Figure 10– Section B through E by 19 throug22A-UV fluorescence. B-white light reflectance photograph.

Ventral feetknees and thighs-19 through 22 (Figure 10)
A very faint bodoutline idiscerniblin this section, even ifluorescence photos. Thfeet arnot defined. Thleg outlinand scourge markings arlimited by a weave line appearinbluin fl uorescenemissiowhere thweave directiochanges.Thiis an area of”no-print.”
Thcentral watestain at B anby 18 and 19 icontrast-enhanced bfluorescenceit absorbs strongly against the emittinbackgroundWhile the water stain at D-20 has fluorescing bordeareas, the opposinone at A-20 does not. Also, the onat D-22 has aunusuallwide absorbing boundary. Ain the othescourgereas, the scourges rudiagonallleft to loweright, and both diffuse and scratch-likmarks, somperpendiculato thleg, are visible. See thlefleg at B-20 and 21. Somscourges appeato bbounded by the central watestain. No scourges can be found othe ankles.
On thfeet, twblood stain areas are distinguishable othright foot; the smalleonidenserthlarger has a fluorescing bordeareaCuriouless densely absorbinflowwithoudefinite boundartraifrothblood spots. They dnot resemblthusual bloocharacteristics. Thsmal circular mark above thwater boundary at D-22/21 has thfluorescencoloroa scorch: regrading to a yellow border. To thupper right a 2-inch diametestain containinthree dark lineappears bnuorescence contrast, but not bwhite light. Wax drops seen in thiarea arbright. nuorescercoloreyellowogreen. At the loweedge, D-22, two sharp-edgemarks visible as dark brown emibrighwhite in nuorescence.


Discussion-Laboratory experiments

In fluorescence photographs most of the details are visible in contrast with the Shroud linen, which itself fluoresces. With the exception of lightly scorched areas and some water stained areas, the Shroud features absorb UV energy without visible emission. Compared with modern linen, the Shroud linen fluoresces less brightly.
Iemits a yellowgreen color. Modern linen can be artificially aged by baking at high temperatures (125°-150° C) to the point where its reflected color and fluorescent emission approach those of the Shroud.When foreign materials are applied to the linen, a reaction which results in locally visible darkening of the linen can be stimulated by air baking as above.
These experimentshave led to the interpretation that the body image is the result of locally accelerated dehydration/oxidation and conjugation of the cellulose molecular structure. Images produced in hours at high temperature are comparable in both reflectance and UV stimulated emittance to images produced at normal temperatures during longer time intervals (years?). Laboratory-produced images were photographed using the same equipmentas was used in Turin. Exposure to sunlight of wavelengths less than 340 nm influences the rate and degree of cellulose degradation.
Laboratory data for whole blood displayed total absorption, which is in agreement with the Shroud data.
Weak 
scorches, which in white light have densities and colors similar to body image areas, show a significant difference with UV fluorescence photography.
Scorches emit a reddish brown fluorescence while the body image is nonfluorescent. The significance of this difference is evident in relation to the suggestion that the body image was caused by contact with a hot statue or was scorched by other means. Laboratory-produced scorches emit a bright greenish-yellow fluorescence if they were produced in air and reddish if produced under conditions of limited available oxygen. The scorches
associated with the fire of 1532, during which the Shroud 
was involvedattest to the rapid consumption of the available oxygen. 1Their reddish emission iprobably due to furfurals, which can be produced under such conditions.
Linen lightly scorched by a soldering iron in air shows the greenyellow emission, often distributed in plumes of deposited pyrolysis products. We demonstrated in one experiment that the material of the plumes could be transported by water, but the underlying scorched cellulose retained a bright yellowgreen fluorescence. This demonstration together with the observed absence of body image fluorescence is strong evidence against the cause for the body image being a scorch.
A quite frequent hypothesis is that the body image was painted. The binders used in paints as early as the 14th century would be made of proteinaceous materials, animal collagen being a favored materialegg white and gelatin are other examples. But these collagens would inherently be contaminated by fluorescing amino acids. 1Random sampling of book bindings and illustrations from the 14th and 15th centuries were observed to emit bright fluorescence when excited by long-wave mercury vapor lamp excitation.
Microchemical analyses on fibrils retrieved from the Shroud have shown the absence of paints, pigments, stains, dyes and protein in body image areas.14


Conclusion
The sharp detail revealed for the first time, particularly in the scourges, suggests that intimate cloth-body contact occurred. The detail (and contrast) is only slightly less prominent on the front than on the dorsal image, indicating that the large difference in weight for each side had only a minor influence on the imprinting of the scourges. This observation is contrary to what might be intuitively expected, and it might be a clue to some future understanding of the image production mechanism.
The 
occurrence of contact could also have transferred substances present on the skin to the cloth where they stimulated the cellulose alteration process and caused an image of the body to develop as local darkening of the linen.7
Hypotheses 
such as scorccause or paint are contradicted by the fluorescence photography results.
UV fluorescence photography has revealed some near-invisible details, many of which require explanation. For example, the pattern of distinct burn holes has characteristics unlike the burn damage attributed to the 1532 fire. Areas in the weave where the image density abruptly decreases (e.g., sides of the face) might actually contain very faint images which possibly could be retrieved by using stimulating radiation of shorter wavelengths. The property of the linen thread that didn’t develop image density should also be discovered. The 8-cm side strip running the length othe Shroud shows weft bands that are continuous with the main body of the Shroud. Similar appearances result from backlighting and low-energy radiography. The suggestion is that this strip was not separatefrom the main body over its entire length.
Many 
of these unexplained details might relate to the history of the Shroud.
Another feature requiring explanation is the lighter bordering area seewith many bloodstained reas. The interpretation is that blood serum ipresent. It might have acted to retard the image development reactions associated with the body image. Fibrilfrom many water stain fronts and frothe area between the head images contain blood particles.14   Further discussions are in preparation.15


Acknowledgments
We appreciate the assistance given by D. Devan and other members of the STURP team, and also acknowledge the cooperation extended by the church officials iTurin. J. Druzik, Conservation CenterLos Angeles County Museum of Arts, critically reviewed the manuscript.
About the authors– Vernon Miller is Head of t he Scientifiand Industrial Photography Department at the Brooks Institute of Photography, Santa Barbara, California. He was the chief scientific photographer fothe STURP team in Turin, and has employed variety of image processing techniques to the photographic data obtained.
Samuel Pellicori ian optical physicist with the Santa Barbara Research Center. Hhabeen evaluating and simulating in the laboratory some othe spectrophotometric, fluorometric and microscopidata he collected in Turin.
Address correspondence 
to Samuel Pellicori, Santa Barbara Research Center, 75 Coromar Drive, Goleta, California 93017.


References
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2. 
Kenneth F. Weaver, “The Mystery of the Shroud,” National Geographi157, 730 (1980).
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9. 
V. Miller and D. Lynn, “Photography of the Turin Shroud,” Science and Technology, Feb. 1981 (in Dutch).
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S. F. Pellicori, “Transmittances of Some Optical Materials foUse Between 1900 and 3400 A,” Appl. Opt. 3, 361 (1964).
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R. N. Rogers in Reference 1, p. 133.
13. 
Eric J. Jumper, John P. Jackson, John H. Heller, Alan D. Adler, Samuel F. Pellicori and Raymond N. Rogers, “A Comprehensive Examination of the Various Stainand Images on the Shroud of Turin,” American Chem. Soc. Proc. on Archaeological Chem. (1982). in preparation.
14. J. 
HHelleand A. D. Adler, “A Chemical Investigation of the Shroud of Turin,” submitted to Journal of Forensic Sciences.
15. L.A. Schwalbe and R. N. Rogers, “Physics and Chemistry of the Shroud of Turin: Summary of the 1978 Investigation,” in preparation.

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