PowerArc – HORIBA would i get housing benefit

Users of old style vertical arc lamp housings are throwing away as much as 90% of the lamps output, due to poor collection efficiency. These old style vertical lamp housings have a collection lens in front of the arc lamp and sometimes, but not always, a back reflector behind them. The problem with this old design is that only the light that actually strikes these optical elements is delivered outside of the lamp housing. All other photons emitted by the lamp are wasted, simply heating the inside of the lamp housing. Conversely the unique OBB powerarc™ lamp housing has an enveloping ellipsoidal reflector that collects virtually all of the light emitted by the lamp arc, delivering those photons to a secondary focal point outside of the lamp housing, and it does so without any lenses.

For the same bulb, the OBB powerarc™ delivers 5 to 6 times more light, to the secondary focus!Would i get housing benefit that means that an OBB powerarc™ lamp housing with a 75 watt xenon lamp provides the equivalent optical power of a 450 watt xenon lamp in an old style vertical lamp housing. And it does so with greater power density due to a smaller focal spot, and at a small fraction of the cost of a big old 450 watt illuminator.

We call the OBB powerarc compact arc lamp housing design an ozone free lamp housing regardless of the lamp selected, even in the case of UV enhanced lamps. It is ozone free primarily because it is a sealed lamp housing that is air tight and not air cooled, unlike most arc lamp housings which use air cooling.

The powerarc lamp housing with UV enhanced lamps has been tested following OSHA safety standards. While some ozone was detected outside the lamp housing, the ozone levels in the test room were well below the safe guidelines.Would i get housing benefit of course some UV light is delivered outside the lamp housing and into the air in the test room, and you can even detect this by smell, but not enough ozone is created to pose a health risk or require a chimney for venting.

Air cooled lamp housings have a real problem because they blow oxygen at the UV source, and, like blowing oxygen on a fire, this creates problems. One way to get around this problem with an air cooled lamp housing is to select a lamp that has an envelope that does not emit wavelengths below 250 nm. As such even an air cooled lamp housing will not create an ozone problem since there is no UV output outside the lamp itself. The problem with this solution is that many applications require deeper UV wavelengths.

If you require deep UV output for your application then you necessarily require a lamp that emits deep UV wavelengths.Would i get housing benefit for these applications we recommend a UV enhanced lamp and a suprasil front window for the powerarc lamp housing to get the most UV output you can. Even in this configuration, the sealed powerarc lamp housing is still considered to be an ozone free lamp housing.

Since oxygen is the principle absorber of light in the 150 to 200 nm range, some applications, such as CD spectroscopy, require nitrogen purging to access the lowest UV wavelengths emitted from UV enhanced xenon lamps (down to about 180 nm). For output in the 180 to 200 nm range you will need to nitrogen purge your optical environment, and also to use no front face window on the lamp housing. The housing is now no longer air tight, but the nitrogen purging negates the concern for ozone creation.

The unique OBB powerarc design allows you to choose whatever lamp, reflector and front face window is best for your particular optical needs.Would i get housing benefit and the ozone free design means that your choice is always safe and requires no venting or chimney to deal with.

Although the spectral output charts above do not show data below 250 nm, the powerarc can deliver light down to 180 nm, the lowest available wavelength emission of the xenon plasma. Some arc lamps use quartz envelope bulbs that do not transmit UV wavelengths. These lamps are sometimes called ozone free bulbs because they do not emit in the deep UV and hence create ozone when interacting with oxygen in the air. We offer both ozone free and UV enhanced bulb choices, as well as different window materials for the front output of the lamp housing, so that our customers can choose the best components for their requirements.

Calculation: the total power of the 75 watt xenon lamp is 7.5 watts broadband (7,500 mw).Would i get housing benefit referring to the band pass intensity chart, and graph, for the xenon lamp indicates that at 400 nm there is approximately 5% of the total lamp output in a 50 nm wide band. Therefore in a 5nm bandwidth at 400 nm there will be approximately 0.5% (1/10 th of 50 nm) of the total lamp output. This corresponds to 37.5 mw.

Filter for wavelength selection: if you use a 5 nm bandpass filter for wavelength selection, then there will also be losses through the filter as well as coupling losses for any optics you incorporate. Therefore you might end up with19 mw of energy to work with.

Monochromator for wavelength selection: if you are going to use a monochromator to filter and select the 5 nm output at 400 nm, then there are a number of factors to consider before determining exactly how much light will be available through the monochromator.Would i get housing benefit specifically the slit size required for a 5 nm bandpass, the grating efficiency curve for the grating used, the f/# matching of the monochromator, and the throughput loss of the monochromator coupling. OBB happens to provide a tunable powerarc™ illuminator that consists of the powerarc™ lamp housing coupled to a 200 mm focal length monochromator. When using the 75 watt xenon lamp with the f/4.5 ellipsoidal reflector, a considerable amount of light in the original focused spot doesn’t even get through the narrow 1.25 mm slits required to obtain a 5nm bandpass with a standard 1,200 l/mm grating. Firstly we have to remember that the 5.4 mm spot is actually the FWHM of the total light focused. This means that approximately half of the total power is outside a 5.4 mm diameter. So, only about 10% of the total focused light gets into the monochromators narrow 1.25 mm slit in the first place.Would i get housing benefit additionally, depending on the grating used, its wavelength angle, its efficiency curve as well as the coupling loses of the monochromator you will have a total throughput for the monochromator of roughly 30%. This results in about 1 mw of energy delivered through the monochromator at 400 nm in a 5 nm bandpass. Still, 1 mw in a 5 nm bandpass through a monochromator is significantly more than any other commercially available alternative. Refer to the tunable powerarc™ web page for the corresponding output curve. Also remember that other monochromator options are available with differing focal lengths and grating resolutions and grating blaze angles that will have an impact of the total throughput.