Sirchie sells a low cost ALS called the BlueMaxx. Essentially a powerful flashlight that is fitted with a high-quality excitation filter that only allows blue light to pass, the BlueMaxx is used in conjunction with an orange barrier filter to allow only the fluorescent evidence to be visible. The BlueMaxx starts at about $150, and as expected at that price, the BlueMaxx is not as powerful as the larger more expensive ALS tools and the wavelength is not tunable. However, acquiring a BlueMaxx is a great way for smaller agencies to learn more about the benefits of ALS technology.
Rofin, Spex, Omnichrome, and others market ALS systems that are highly tunable and portable, making them ideal for locating evidence in the crime lab or in the field. These units range in price from just under $8,000 up to $16,000.
Boulder PD uses the Rofin Polilight PL500. Manufactured by Rofin Australia Pty. Ltd., the Polilight is built around a 500-watt xenon gas bulb. It is very bright, which is useful because it lets you scan a room for evidence much more quickly. The Polilight offers 12 bands of light, and each can be fine-tuned in 30-step increments. Wavelengths from 350 nm to 700 nm-UV and all the colors of the visible spectrum-are possible. This allows for a great degree of flexibility in using the instrument. The various wavelengths are useful not only for locating evidence that fluoresces or absorbs light, but also to reduce colored background interference when photographing fingerprints.
Another great feature of the Polilight is that it uses a unique liquid light wand instead of fiber optics to transmit the light. The six-foot wand consists of a stable saline gel, which transmits more light than fiber optic cables.
The Polilight is user friendly, and has a switch mode power supply that makes the instrument less susceptible to voltage fluctuations, especially when powered from a generator in the field. The Xenon bulb has a life of 1,000 to 1,500 hours and costs about $1,200 to replace.
Argon laser-based ALS systems are another option. Sirchie's SceneSweeper is a great product. It's a high-output laser that is tunable to four different wavelengths within the visible spectrum, 457 nm to 515 nm. Another nice thing about the SceneSweeper is that the fiber optic cable is 15 feet long, which means the unit can be placed in the center of a room and the operator can search most average size rooms without having to move the instrument.
Argon lasers do not have IR capability, nor do they have as many available wavelengths as xenon bulb ALS systems. But they do have some advantages as well. For example, on the SceneSweeper, the beam can be focused. This means that with the proper attachments, the SceneSweeper can be used for firearm projectile trajectory work, which eliminates the need to purchase a dedicated laser.
Reflective UV imaging is based on the principle that different objects and/or substances react differently to light. A short-wave (254-nm) reflective imaging system at its most basic consists of a specialized 254-nm UV light source and a handheld optical instrument that is sensitive to UV light. The 254 nm UV light is projected onto an area that might possess latent fingerprints. Then the Latent fingerprints reflect the UV light, allowing the operator to see an undeveloped fingerprint through the handheld scope.
This technology is also beneficial to use in conjunction with chemicals that cause blood to fluoresce such as Luminol and Starlight Bloodhound. The luminescence fades quickly with these products, and the UV-sensitive scope allows more blood to be seen for a longer period of time.
The first time I used the Sirchie Krimesite Scope system I examined a postcard that had just been delivered via the US Postal Service. I pointed the 254-nm light onto the card and looked through the handheld scope. Literally dozens of partial latent fingerprints were visible that could not be seen with the unaided eye.
Unlike ALS systems, which must be used in darkened areas, reflective short-wave UV imaging tools can be used under any lighting conditions, including outside during daylight hours and inside a brightly lit room. Spex, Sirchie, and Elephant Engineering market these systems to law enforcement, and the prices range from about $12,000 to $18,000.
All law enforcement agencies operate under tight budgets and the money for new technology is not always easy to obtain. I have spoken to evidence technicians from many departments and have heard similar remarks that the police chief or sheriff doesn't see the need for new equipment. The "We've gotten along fine without it, so why do we need it?" attitude prevails.
This is why many companies have equipment loan programs for departments that are interested in purchasing these evidence collection products. Allowing command staff to see a product in action is often the best way to convince them that the department will ultimately benefit from the purchase.