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Pen-Ray® FAQ Sheet

UVP invented the Pen-Ray® Lamp and can provide the most experience, history and knowledge in the industry.

Pen-Ray Lamp Family


  • Chromatography
  • Spectroscopy
  • Atomic absorption
  • Fluorescence
  • HPLC detectors
  • Ozone production
  • Photochemistry
  • Water sterilization
  • Immunoassay analyzer
  • Air pollution monitoring
  • UV/ozone cleaning
  • UV barcode reading
  • Automobile emission testing
  • Wavelength calibrations
  • TOC analyzer
  • Fluoromicroscopy
  • UV sensitive catalyst reactions
  • Microlithography
  • S02 analysis
  • Approved aerospace applications
  • Mercury analyzers
  • Penetrant/tracer inspection
  • Sterilization/germicidal
  • Fluorometry


What is a Pen-Ray Lamp?

A Pen-Ray Lamp is a low pressure cold cathode Mercury, Zinc, Cadmium or Rare Gas Lamp (Argon, Krypton, Neon or Xenon gas) used for a variety of applications such as: wavelength calibration (chromatography and spectroscopy instruments), photochemistry, fluorescence, ozone production, sterilization (germicidal), and air pollution monitoring equipment (Zinc laps). It uses a double-bore quartz tube to allow the electrode placement to be at one end of the lamp to provide insertion into restricted areas. Depending on the lamp characteristics, primarily the lighted length, the power requirements to the lamp can range from 2-30 watts and the lamp can produce from 40 microwatts/cm2 to over 20 milliwatts/cm2 at a range of 1" (2.5cm) from the target. UVP invented the Pen-Ray Lamp and can provide the most experience, history and knowledge in the industry.

What is the spectral output of a Pen-Ray Lamp?

Depending on the element used (Mercury, Zinc, Cadmium or rare gases) the spectral output will range from 160nm to 4,000nm. An output chart is attached for each element. The quartz sleeve will transmit between 160 and 4,000 nanometers. By substituting different types of quartz, UVP can provide lamps that either enhance the output of 185nm (ozone production) or reduce it to near zero levels. Lamps can also be phosphored to increase energy output at 285nm, 302nm or 365nm for applications of broad band energy emissions.

Can UVP manufacture custom designs for their customers?

Yes! 90% of our work is custom design for OEM applications. Custom design options include lighted length, total length, cord/connector type and length, phophors, shields, handle types, intensity orientation collars, ozone free or enhancing, holders/reflectors, grid dimensions, and field Pack options (portable lamp with 9 volt battery). UVP would be happy to investigate any custom request.

How long do Pen-Ray Lamps last?

The lamps are rate for 5,000-8,000 hours but can last up to 16 years (documented) depending on use and applications. Generally the more startups imposed on the lamps (as opposed to continuous use), the shorter the life due to wear on the electrodes as a result of the initial spark needed to ignite the lamps. In the case of Mercury lamps, the primary emissions peak at 254nm will decrease steadily with time due to quartz solarization. This will yield a net output of approximately 70% after 2,000 hours. The effect will then stabilize for the remainder of the life of the lamp.

How small in size can the lamps be manufactured?

UVP has a series of Pen-Ray lamps called Calibration Lamps which are designed specifically for OEMs with very small spaces available in their equipment. The smallest lamp is 1.85" (4.7cm) with a lighted length of 0.06" (1.5mm) and excludes a handle to minimize the length.

What is the typical energy requirement of a Pen-Ray Lamp?

Depending on the size of the lighted length, the energy requirement can range from 2 to 30 watts. Example: a standard Pen-Ray Lamp, part number 90-0012-01 with a lighted length of 2.12" (54mm) would require a starting voltage of 800 volts and an operating voltage of 270 volts with a current feed of 18mA (4.9 watts). These values are considered nominal.

What is the typical intensity value at 254nm for a Pen-Ray Lamp?

Depending on the lamp, this value can range from 40 microwatts/cm2 to over 20 milliwatts/cm2 at a distance of 1" (2.5cm) from the target. Using the example above (90-0012-01), the lamp will provide a value of 4500 microwatts/cm 2 (nominal).

Can I use a different current feed to change the intensity of the output?

Yes. The lamp will respond to different current feed and produce a different intensity. The lamp response to the current feed is like a bell shaped curve: The more current you feed, the higher the intensity you will produce to a certain point (dependent on the lamp). Beyond this point, the lamp intensity will decrease as you increase current.

Can the Pen-Ray Lamps run off a DC current?

Generally, no. When using a Mercury lamp UVP recommends using an AC power source. If DC into the lamp is used, a phenomenon called Mercury migration occurs. This is when the Mercury in the lamp is driven in one direction toward one electrode. When this happens the Mercury falls out of the arc and intensity is reduced. UVP does provide DC/AC converters to provide 12Vdc and 24Vdc power feed options from the power source.

How can I get more information?

Please feel free to inquire either through our Cambridge, England office or directly from our Headquarters and manufacturing location in Upland, California. If communicating directly to UVP Headquarters, please fax (909) 946-3597, call (800) 452-6788 or e-mail us at info@us.analytik-jena.com We would be pleased to hear from you.