Portable, Compact Forensic Laser System

TracERYour Reliable Source for Evidence Recovery

Superior Reliability & Performance

Why lasers?The laser has long been recognized as theoptimum light source for latent evidencedetection, particularly of fingerprints, andalso for bone fragments, skin, and tracesof bodily fluids. This view is widely heldthroughout criminology—by academics,expert witnesses, crime lab technicians,and crime scene investigators. The laser’sundisputed superiority is a result of severalunique properties that cannot be matchedby lamp-based systems. The most importantof these properties is spectral brightness.

Brightness.The main purpose of a forensic light sourceis to excite fluorescence in tiny or traceamounts of evidence, allowing it to be seenand photographed in situations where it isnot visible in ambient light or with conven-tional dusting techniques. This excitationmay involve inherent fluorescence and/ortreatment with fluorescence dyes such asninhydrin, DFO or rhodamine 6G.Withfluorescence, light is absorbed in one wave-length band (color) and re-emitted in a longerwavelength band.

Fluorescence is actually a fairly weak effect,but it works very well if the light source ispowerful and confined solely to the narrowwavelength range that is absorbed by theevidence. Blocking filters in goggles or in frontof a camera then allow only the longer wave-length fluorescence band to be seen, with nobackground. If the light source itself does notgenerate any light in this viewing band, thenvery high contrast images are possible, evenfor trace amounts of evidence.

Thus, fluorescence requires a powerful lightsource with output only in a narrow wave-length band. Scientists call this “spectralbrightness.”The spectral brightness of alaser is many orders of magnitude greaterthan any lamp source. An ALS, or alternativelight source, can be used by incorporatingan optical filter, but this just dissipatesmost of the lamp output, leaving only asmall amount of power in the target wave-length window. That is why a few watts oflaser light can be much more effective thana lamp system rated at 100s of watts.Basically, higher brightness equates to betterdetection sensitivity.

• Compact, portable, modular color,laser system

• Long-life battery or AC mainsoperation

• Superior sensitivity compared toalternative light sources (ALS)

• Cost-effective architecture

• OPSL technology for solid-statereliability, longevity and wavelengthflexibility

• Optimum wavelength forcommon dyes- Green (532 nm) 6W & 8W- Yellow (577 nm) 3W & 5W- Blue (460 nm) 2W

Now you can afford to see what you’ve beenmissing.

“Coherent's TracER forensic laser illuminates evidence details not easily seen by other means.The result is an incredible high-contrast image that clearly shows the fluorescing evidence.I have never seen a more powerful light source in operation.”

—David Spraggs, City of Boulder PD, Police Magazine, February 2008

DFO found on paper using TracERImage courtesy of ATF

TracER – Trace Evidence RecoveryThe TracER™ is a fully hand-portable,modular color, laser-based system designedand performance-optimized to be theultimate tool for trace evidence detection,particularly of latent finger prints and othertrace evidence such as bone fragments, hairfibers and fluids. It is a highly cost-effectivelaser source for use in crime labs andat crime scenes, as well as for covert andsecurity applications.

TracER Highlights R6G on Tin FoilImage courtesy of ATF

Why solid-state lasers?The argon ion laser, with its blue/green out-put, was the first type of laser used for traceevidence detection.While offering greatlysuperior capabilities compared to lamps,these lasers unfortunately suffered fromsignificant practical limitations. They werebulky, power hungry and required watercooling. Air-cooled “pseudo-portable” versionswere sometimes used in forensics, but thesewere limited to low power output. Also, theoutput power of ion lasers slowly fades in afew years as their plasma tubes age.

This situation changed somewhat with theadvent of diode-pumped solid-state (DPSS)lasers. These lasers were more compact andrugged than ion lasers and required less cool-ing. Their higher electrical efficiency allowedthe use of conventional power outlets.

These lasers also offer better evidencedetection than ion lasers because of theiroutput wavelength is fixed. The argon-ionlaser, as with an ALS can emit over severalwavelengths simultaneously, thereby reduc-ing the fluorescent signal. Fluorescent dyes

only absorb light in a very narrow wavelengthband, and the 532 nm output of the DPSSlaser is closer to the middle of this band thanthe 514 nm output from the argon ion laser.In addition, the DPSS laser is more intense,and produces substantially more power thanthe typical argon laser. As a result, the DPSSlaser makes the dye fluoresce more brightly,generating a higher contrast image andmaking treated evidence easier to see.*

Why TracER?The biggest obstacles to using 532 nm diode-pumped solid-state lasers has been their highcost and still relatively large size. That is whereTracER offers a solution. Earlier DPSS lasersemitted light from a glass-like crystal (YAG orneodymium vanadate), but TracER utilizes thelatest OPSL (optically pumped semiconductorlaser) technology. This type of technology hasbeen pioneered by Coherent and is field-provenin long-life bioinstrumentation and displayapplications. Plus, the inherently rugged,long-lifetime OPS laser is also simpler tomanufacture than glass crystal lasers. Thisresults in a product with lower cost, smallersize and superior performance.

The biggest benefit of OPSL technology,however, is the ability to produce high outputpower at custom wavelengths therebyproviding a truly innovative technology tolaw enforcement. This high power providesthe sensitivity to find evidence and printsyou could never find with a lamp or an ionlaser even under the most adverse conditions:old prints, prints on metals, and on porousmaterials like paper and stone.

TracER also delivers the ultimate portability.Its OPSL technology is incredibly efficient,both electronically and optically. That is whyit can be used in remote space-constrainedand weight-restricted applications.We’vetaken full advantage of this efficiency byincorporating long-life laptop batterytechnology, for true go-anywhere portabilityIn fact, TracER is the most compact, portable,high-power forensic laser based systemavailable today.

“The battery option for the TracER system has proven to be extremely useful at a number ofcrime scenes.”

—The Forensic Science Service, United Kingdom

* Fingerprint Detection with Lasers, by E. Roland Menzel,pub. Marcel Dekker, Inc., 2nd edition, 1999.

TracER uncovers ink on corpseImage courtesy of RCMP

See the Advantagesof TracER

TracER

ALS

R6G on plastic500 ms shutter time**

DFO: 56 vs. 38identifiable impressions***

Untreated Prints on White Paper:“Inherent Fluorescence”****

Why Coherent?Coherent is the word’s largest laser company.Wehave a long and successful history of supplyinglasers for forensic applications, dating back to theearly years of argon ion lasers. Our lasers are usedby many police departments and forensic labsthroughout the US and overseas, as well as by theFBI and the military.

As the world’s largest laser company, Coherentalso spends more on R&D than any other lasercompany. So with Coherent as your partner you

always have access to the latest, state-of-the-artlaser technology. A laser also represents a signifi-cant capital investment, and with Coherent youcan be sure you’re getting a laser that will offerleading-edge performance for a long time.

When you partner with Coherent, your laserinvestment is backed by an experienced worldwideservice and support team, too. No matter whereyou operate your laser, if you need our help, we’llbe there.

“Having used the Coherent TracER in serious crime caseworkin Northern Ireland for the past six months, Forensic ScienceNorthern Ireland considers that the TracER proved its valuein the laboratory and at crime scenes. The TracER consistentlyfinds imprints not detected by alternative light sources; upto 30%more in some cases, while enhancing weaker imprints,thus making them viable for photographic capture. Furthermore,TracER's battery system enables its use directly at scenes wheremains power is absent or unsafe. TracER's capabilities, portabilityand ease of use have made it invaluable for light searching andphotography within FSNI's Specialist Fingerprint Unit.”

—FSNI, United Kingdom

** Images courtesy of ATF,Walnut Creek*** Images courtesy of RCMP: OIC Lower Mainland District

**** Images courtesy Brian Dalrymple (Observed with goggles and bandpass filter)