Tunable KiloArc™

  • Need a CW laser that is tunable from 250 to 1,100 nm? yes
  • Need it to deliver Hundreds of Milliwatts of energy? yes
  • Need it to be so simple that anyone can use it? yes

If this sounds like the light source you need, then OBB has the answer. The Tunable KiloArc™ Illuminator provides all of these benefits, it just isn’t a laser.

Tunable KiloArc™ Illuminator


Tunable PowerArc™ Illuminator

Tunable KiloArc Curve
Tunable KiloArc™ Illuminator equipped with 1000 watt Xenon lamp and 1,200 l/mm x 500 nm blazed grating. Here the adjustable bandpass was set to 20 nm.

Think of the OBB Tunable KiloArc™ Illuminator as a continuously tunable high intensity laser. It can produce tunable monochromatic light with hundreds of milliwatts of power, and an overall available spectral output from 180 nm to 24 microns.

Key Benefits of the OBB Tunable KiloArc™ Illuminator

  • Continuously tunable from 180 nm to 24 microns.
  • Hundreds of Milliwatts of energy.
  • Push button start and simple dial the wavelength tunability.
  • No special cooling or ozone venting required.
  • An Illuminator that is so easy to use, anyone can operate it.

Don’t need so much Power?

If you don’t need this much intensity in a tunable light source then we also offer a Tunable PowerArc™ Illuminator. It delivers milliwatts of power, is smaller and portable, and it is about half price of the Tunable KiloArc™ Illuminator. For more information go to Tunable PowerArc™ Illuminator.Tunable KiloArc


Tunable KiloArc™ Illuminator

Consisting of a unique arc lamp housing tightly coupled to a 0.2 meter monochromator, the Tunable KiloArc™ Illuminator is a self aligned illuminator that generates hundreds of milliwatts of intensity and offers the versatility of continuous wavelength and bandwidth selection. The wavelength can be set manually or, for ultimate flexibility, it can be scanned under computer control. The Tunable KiloArc™ Illuminator could not be easier to operate. The system is air cooled and requires no ozone venting. Simply push the start button and dial the wavelength and bandpass of output that you require. It’s that easy!

Arc Lamp Hardware

Lamp Housing

You would have to buy 6 old style vertical lamp housings to deliver the same number of photons that a KiloArc™ delivers to a single point!

At the heart of every OBB KiloArc™ is a proprietary on-axis ellipsoidal reflector. Our reflectors collect up to 70% of the radiant energy from the arc lamp, versus only 12% for typical condenser systems in vertical lamp housings. The ellipse literally wraps around the arc lamp, collecting 5 to 6 times more output power than from a conventional system.

The arc source is located at one focus points of the ellipse, and the radiation is reflected by the ellipse to the secondary focus which is actually outside of the KiloArc™. Since the light is brought to a focus by reflection rather than refraction (through a lens), there are less losses from absorption or lens-surface back-reflection. This design is so efficient that an OBB Lamp housing can deliver  up to 11 times more optical power into a given smaller area than a conventional lamp housing.

Our ellipsoidal reflectors are proprietary in design and the coating used. They are NOT electro-formed reflectors, which can distort with heat, and can degrade within months. Our proprietary design ensures that distortion of the critical ellipsoid cannot occur as the lamp reaches its operating temperature. This ensures thermal stability of focus. The coating ensures reasonably long operating life, typically 2–3 years.

The KiloArc™ ellipsoidal reflector is an f/4 reflector. The f/# is important when considering matching the KiloArc™ source to some other components like, fiber optics, liquid light guides or monochromators. However f/# for an ellipsoidal reflector is not an indicator of light collection as it is in a simple lens design. The shape and size of the ellipsoidal reflector determines how much light is collected from the lamp arc. The f/# only determines the focal cone angle.

The KiloArc™ is air cooled. However since the system uses ozone free lamps, there is no ozone or venting requirements, although there is an exhaust hose adapter if you want to vent the warm air out of a lab.

The OBB KiloArc™ is a sealed arc lamp housing with a quartz window through which the focused light is delivered. Below is the spectral transmission curve for the quartz window.

Quartz Spectral Transmission Curve



You have a choice of lamps depending on the spectral output that you require. Of course you may order different types of lamps for the housing, they are interchangeable.

There are two types of arc lamps available—xenon and mercury. The xenon gas used in the lamp provides continuous spectra from 180 nm to 2,500 nm of course at varying intensity (refer to spectral output graph). The mercury provides a line spectra (refer to spectral graph). The spectral curves for xenon and mercury are normalized (relative intensities) therefore it is not obvious that the mercury lamps, intensity—where it emits, exceeds that of the xenon lamp. Because of the smaller arc size, the mercury lamp can also provide greater intensity in a smaller area (greater brightness) than the xenon lamp.

We also have an optional tungsten-halogen filament lamp for NIR applications.

Arc lamps come with a quartz or suprasil envelope depending on the application. Quartz lamps do not transmit the deep UV below 240 nm. Suprasil lamps do transmit  the deepest UV output from the arc down to about 180 nm. For either type of lamp envelope our unique lamp housing design does not create ozone and therefore requires no ozone venting.

Lamp Wattage

Lamp Type

Nominal Arc Gap

75 watt

Compact Arc Xenon

0.8 mm

100 watt

Tungsten Halogen Filament

4 x 2 mm

100 watt


0.25 mm

75 watt

Suprasil Compact
Arc Xenon

1.3 mm

150 watt

Compact Arc Xenon
Ozone free

2.1 mm

150 watt

Compact Arc Xenon

2.1 mm

The 75 watt xenon lamp and 100 watt tungsten-halogen lamps require no cooling whatsoever. The larger wattages of lamps require water cooling.

You can either get your water directly from the cold-water tap (can be a problem if the water is hard or when water is not available) or from an inexpensive circulating water bath option that we provide.

We have selected water-cooling over air: because it allows us to make a more compact housing; seal in the ozone and eliminates the need for venting.

Power Supply

The KiloArc™ illuminator has a dedicated 1,000 watt power supply and igniter built into it. The power supply is a high efficiency switch-mode type supply. It is rated at 1,200 watts to ensure that it is not operated at the limit of its range. This provides better stability and longer lifetime when operated at 1,000 W. The KiloArc™ has triple shielding and electronic filtering to ensure that there is no RF transmitted or radiated out of the illuminator to interfere with sensitive equipment, like computers.


The internal igniter provides a 45 KV pulse for reliable lamp ignition. Ignition noise can disrupt, or even destroy, sensitive equipment in the vicinity of an arc lamp during start-up. This can be quite a concern in a crowded lab environment. OBB Engineers carefully designed and tested the KiloArc’s triple shielding housing and electronic filtering to ensure that there is no RF transmitted or radiated out of the illuminator.

KiloArc™ Power Supply and Igniter Specifications


210–240 V AC 50/60 Hz


45 kV starting pulse

Power Rating

800–1200 watts (adjustable) — recommended 800–1000 watts

Output Volts Compliance

17–23 VDC

Output Current Limi

70 A rms

Smart Features

There are two LED indicators on the back, one called the “STATUS” which shows the modes of operation: cool down, stand by, or error. The other is an ERROR indication. It senses problems and displays error codes when they occur.

Particular considerations were paid to safety. The lamp chamber and power supply are constantly monitored for heat, as well as the airflow for cooling. If there are problems the lamp will shut down automatically and you will receive an appropriate error message. If the access door to the lamp is loose or open the lamp will turn off, or not ignite..

We tried to make the operation as fool proof, safe and reliable as possible, making the KiloArc™ ideal for commercial applications.

Mounting Information

The KiloArc™ can be mounted rigidly by removing the adjustable feet that come with the illuminator and exposing the four tap holes (6-32) shown on the bottom view below. There are also four mounting holes (6-32) on the front face of the KiloArc™, as shown on the front view below. These front holes are for attaching OBB's adapter tube but they can be used for any other mechanical assembly.


Front View

Right View

Left View

Bottom View

Top View

4-Inch Exhaust Hose Adaptor

The KiloArc™ does not generate harmful levels of ozone (less than a typical copier). It does generate some heat. Therefore venting is not a requirement, but if you do desire to vent the exhaust from the KiloArc™, select this option.

IR Absorbing Water Filter

The KiloArc™ light source is coupled to a monochromator with a light tight adapter tube which contains an IR absorbing water filter.  The IR absorbing water filter is used to protect the optical elements in the monochromator from the very intense IR heat delivered by the KiloArc™ illuminator. These cylindrical metal devices are filled with water or some other IR absorbing liquid, such as copper sulfate, and have two quartz windows on either end to allow light to transmit through the absorbing solution. The cylindrical walls are water jacketed to allow cooling water to be circulated around the IR absorbing solution itself to keep it from overheating.

The standard IR absorbing water filter that comes with the Tunable KiloArc™ is made of aluminum which can be used with distilled water as the absorbing solution. There is an optional stainless steel filter that can be filled with distilled water, copper sulfate other IR absorbing liquids.

Distilled water is an excellent UV-Vis-NIR transmitter and IR absorber. It will transmit most of the light above 200 nm and absorb almost 100% of the light above 1,000 nm.

There is an optional filter mount that can be attached to the output side of either IR absorbing water filter to allow for multiple 2” square filters to be held.

Monochromator Hardware

Optional Ports

This extremely rugged monochromator is built from a single solid metal casting that includes the base plate, optical mounts and all four sides of the unit. Inside the monochromator has extensive baffles to reduce stray light. There is an entrance and exit baffle box at the entrance and exit silts, as well as a center baffle that separates the input side from the exit side of the monochromator.

The monochromator has four optional ports that can be utilized for two inputs and two outputs. In the standard configuration it comes with one entrance and one exit port. This gives you a choice of four different input/output geometries:

180° Straight Line – with folding mirrors on entrance and exit

90° Right Angle – with folding mirror on the exit side

90° Left Angle – with folding mirror on the entrance side

360° – with no folding mirrors

180° Straight Line

90° Right Angle

90° Left Angle


You can also elect as an option to have two entrance ports or two exit ports. This option adds an appropriate flipping mirror(s) and slit assemblies. The flipping mirror is manually switched to receive light from either entrance port, or to deliver light to either exit port depending on the configuration.

Dual Exit Ports

Dual Entrance Ports

Dual Entrance and Exit Ports


The monochromator slits are continuously adjustable manual slits with micrometers for adjustment from 0 to 6 mm. The micrometers have a digital readout of the physical slit size selected. The slit housing also has a manually sliding shutter to quickly shut off or open the light path. This manual slider also has a wedge height adjustment to allow you to select a slit height anywhere from 0 to 21 mm.


There is a wide selection of gratings to choose from depending on the optical requirements. All gratings are 50 x 50 mm flat gratings. The Ruled gratings have better optical throughput and Holographic gratings have improved stray light characteristics. Ruled gratings have two fundamental parameters to choose from; the groove density, expressed in grooves (or lines) per millimeter, and the blaze angle which nominally refers to the peak reflectance wavelength expressed in nanometers.
The groove density affects the resolution and mechanical scanning range of the monochromator. Below is a reference chart showing the affect groove density has on the mechanical scanning range of the monochromator as well as the reciprocal linear dispersion.

Groove Density

Mechanical Scanning Range (nm)

Reciprocal Linear Dispersion (nm/mm)

2,400 g/mm

0 to 550 nm

2 nm/mm

1,200 g/mm

0 to 1,100 nm

4 nm/mm

600 g/mm

0 to 2,200 nm

8 nm/mm

300 g/mm

0 to 4,400 nm

16 nm/mm

150 g/mm

0 to 8,800 nm

32 nm/mm

An optional dual grating mount allows you to select two different gratings, say to optimize throughput in different wavelength ranges. The gratings are positioned back to back and a switch dial is available at the top of the monochromator to manually choose which grating is to be used.

Below is a list of our standard gratings. Other gratings are also available upon request.

Available Gratings

Part #


Grating Curve


600 g/mm, 1,250 nm blaze

Download Curve


1,200 g/mm 300 nm blaze

Download Curve


1,200 g/mm 400 nm blaze

Download Curve


1,200 g/mm, 500 nm blaze

Download Curve


Holographic grating 300–800 nm

Download Curve


75 g/mm 10.0 µm blaze

Download Curve


150 g/mm, 4.0 µm blaze

Download Curve


300 g/mm, 2.0 µm blaze

Download Curve


600 g/mm, 750 nm blaze

Download Curve


600 g/mm 1.0 µm blaze

Download Curve


1,200 g/mm, 600 nm blaze

Download Curve


1,200 line/mm, 750 nm blaze

Download Curve

Wavelength Control

The monochromator wavelength is controlled with a manual dial and readout. The readout is designed to be in true wavelength in nanometers for the 1,200 g/mm grating. For other gratings you have to multiply the dial readout by a factor depending on the actual grating resolution. For example with the 600 g/mm grating you multiply the digital readout by 2 to arrive at the true wavelength position of the monochromator.

Programmable Computer Control

An optional computer control accessory is available. It includes a stepper motor assembly, an MD-2000 USB motor controller interface box and a LabVIEW* driver for computer control of the monochromator wavelength with LabVIEW software from National Instruments.

A very simple software package is also provided by OBB to remotely select the wavelength and control the shutter. Requires Windows 2000 or Windows XP operating system.

Software Screen Shots


*LabVIEW is a trade mark of National Instruments


Tunable KiloArc™ Output Curves

You can customize a Tunable KiloArc™ Illuminator to suit your specific needs. The lamp and grating selected primarily determine the performance of the illuminator. However for any given lamp and grating the slit adjustment (or bandwidth) selected will also affect the intensity output of the unit.

Below are a series of intensity output curves for different configurations of the Tunable KiloArc™ Illuminators. There are far too many variables to provide output curves for all possible combinations for these illuminators. If you are interested in an illuminator with a different grating than those shown below, then you can compare the grating curves of that grating with one listed below to get a pretty good idea of how your particular illuminator will perform.

The Tunable KiloArc™ Illuminator can deliver up to 1 watt of tunable light output!

Optical Performance Specifications

Optical Power > 300 m W (grating, bandpass & wavelength dependent)  
Spot Size at Slit Exit 10 mm (slit dependent)  
Diverging Beam angle (full) 14.4 degrees  
Numerical Aperture (N.A.) 0.12  
Short Term Optical Noise* from 0.15% to 0.2% RMS  
Optical Stability 2%  
  * 1,000 points/s, 1 s duration, 1.5 KHz detector bandwidth  

OBB KiloArc™ Other Specifications

Input 210–240 V AC 50/60 Hz  
Starting 45 kV starting pulse  
Power Rating 800–1200 watts (adjustable) — recommended 800–1000 watts  
Lamp Module Type 1000 W Xenon, 1000 W Mercury/Xenon (proprietary to OBB)  
Lamp Life Typically 1,500 hrs  
Focusing Optics High efficiency f/4 ellipsoid reflector  
Power Precision 0.04% (0.4 watts)  
Output Volts Compliance 17–23 VDC  
Output Current Limit 70 A rms  
Height 329 mm (12.9 inches)  
Width 375 mm (14.8 inches)  
Length 489 mm (19.3 inches)  
Weight 31 kg (68 pounds)  
Window Diameter (D) 127 mm (5.0 inches)  
Center Beam Line Height (without feet) 128 mm (5.0 inches)  

Monochromator Dimensions

Length 241 mm long (9.5 inches)  
Width 272 mm wide (10.7 inches)  
Height 115 mm high (4.5 inches)  
Weight 7.3 kg (16 lbs)  

Monochromator Digital Slit Assembly Dimensions

Length 10 mm thick  
Width 85 mm wide  
Height 180 mm high of which 113 mm (4.4 inches) is above the lid of the monochromator  

Optional Motor Controller Specifications

Power Supply Universal power supply included  
TTL Output Synchronization TTL output each time motor stops  
Stepper Motor Two phase motor 1 A per phase, 200 steps per revolution, 1.8 degree per step  
Maximum Motor Speed 1200 RPM with zero torque  
Maximum Speed with Mono 15,000 nm per minute  
Stepping Motor Voltage 5–12 V  
Stepping Modes Full, Half and Micro steps: 1/8, 1/16, 1/32, 1/64 computer selectable  
Slew Rate 1 to 62,500 micro steps per second  
Calibration Auto calibration of wavelength  
Ramping Linear ramping rate for heavy duty, fast, precision operation  

Higher Resolution Gratings Can Provide Higher Intensities

The data curves above are all from illuminators that had a 1,200 g/mm grating. You will note from these curves that doubling the bandpass, or slit size, typically results in a factor of four increase in intensity. This is true as long as the slit size is the same or equal to the optical spot size. Therefore if you used a 2,400 g/mm grating you would be doubling the slit size from a 1,200 g/mm grating to maintain an equivalent bandpass. Thus a Tunable KiloArc™ Illuminator equipped with a xenon lamp and a 2,400 g/mm grating blazed at 500 nm will give you up to 1 watt of optical power in a 20 nm bandpass. However the 2,400 g/mm grating will only mechanically scan up to 600 nm, see monochromator for more details.

For more information on the Tunable KiloArc™ visit the Tunable KiloArc™ Applications page.


Applications for the Tunable PowerArc Illuminator cover a broad range of scientific, OEM and research applications. These illuminators are the light sources of choice for a variety of spectroscopy systems.

Light Source for,

  • Fluorometers
  • UV /Vis Spectrometers
  • CD Spectrometers
  • Stopped-Flow Spectrometers
  • Tunable Illuminators

Tunable illuminators are also used for a broad a range of applications almost as diverse as the wavelength range across which they emit.

  • Detector calibration
  • Solar Simulators
  • Photochemistry
  • Photo-Activation
  • Photobiology
  • Photovoltaics
  • Spectroscopy
  • Optical Teaching Labs
  • Dermatology


The Tunable KiloArc™ Illuminator is one of many inter-connectable optical components. Hence the name of our company, Optical Building Blocks Corporation. These Optical Building Blocks can be ordered together to form a complete subassembly or they can be subsequently added to one another. In fact there are enough OBB components to choose from to build your own complete optical system for various spectroscopy requirements.

Optical Choppers

If you would like to convert the continuous illumination of the Tunable PowerArc™ Illuminator into a pulsed light source then we have an optical chopper that can do the job. It can be used on a stand alone basis after the output from the monochromator. To learn more click here.

Sample Compartment

If you would like to couple your Tunable PowerArc™ Illuminator into a sample compartment, then we have an ideal solution. The OBB QuadraCentric sample compartment is an excellent unit that has various sample handling capabilities. The illuminator is f/# matched with the collection optics of the sample compartment for optimum throughput. You can then have up to three other input or output optical channels to or from the central sample holder. So you could create a right angle fluorometer or scatter system or a straight through absorbance spectrometer with the appropriate detection components. For each optical channel in the sample compartment there is also a filter holder for wavelength selection. To learn more click here.

Other Accessories

Collimating Lenses

If you need a collimated optical beam, then a collimating lens can be employed for the diverging beam after the light focal point. Be sure to match the collimating lens for your beam diameter requirements and for the f/# of the OBB light source you are considering. OBB offers a number of collimating lenses to choose from. Also if you need a uniform collimated beam of light be sure to consider an optical diffuser.

Optical Diffuser

An optical diffuser is necessary when uniform illumination over a targeted area is required.

Second entrance or exit port

A second entrance to attach for example a second light source or a second exit can be added to the monochromator. It includes a flipping mirror for selecting desired exit or entrance as well as a slit assembly. If you desire both two exits and two entrances for the monochromator you need two of these accessories. Please note that if you select the optional computer controlled shutter, it is positioned inside the monochromator at the entrance port, so selecting this option precludes the use of a flipping mirror on the entrance port of the monochromator.

Dual Entrance Ports

Dual Entrance and Exit Ports

Dual Exit Ports

Dual Entrance Ports

Dual Entrance and Exit Ports

Programmable Computer control

An optional computer control accessory is available. It includes a stepper motor assembly, an MD-2000 USB motor controller interface box and a LabVIEW* driver for computer control of the monochromator wavelength with LabVIEW software from National Instruments.

A very simple software package is also provided by OBB to remotely select the wavelength and control the shutter. Requires Windows 2000 or Windows XP operating system.

Software Screen Shots