Discussion of Prior Art Ultra-violet radiation is widely used in industry and science for sterilization through inactivation of microorganisms, for inducing and promoting various types of photochemical reactions and for controllably exposing various types of photosensitive materials. By way of example, U. S. Patent No. 5,175, 347 issued to the present inventor describes an apparatus for irradiating an object such as a specimen of material with ultraviolet radiation at a selected long, short or mid-wave length. Similarly, Patent No.

3,936, 186 issued to Boland et al discloses an apparatus for exposing diazo printing plates and the like of the character that are used in the graphic arts field. In like manner, U. S. Patent No. 5,288, 647 issued Zimlich, Jr. et al relates to a method by which polynucleotide specimens can be irradiated particularly for the purpose of fixing them to a substrate.

Ultraviolet light (UV), which is electromagnetic radiation in the region of the spectrum located between X-rays and visible light, is typically divided into three principal ranges, namely long wave, mid-range, and short wave. For each of these UV ranges specific applications have been developed.

As a general rule, the desired ultraviolet wavelength is obtained from a fluo- rescent style tube that is an electric discharge device that uses a low-pressure mercury vapor arc to generate ultraviolet energy. The ultraviolet energy released in typical, commercially available fluorescent tubes is primarily at the wavelength of about 254 nanometers. The fluorescent tubes can be modified to release other ultraviolet wavelengths by the use of phosphors, which have the ability to absorb the ultraviolet energy and re-radiate it in other wavelengths. For example, long wave ultraviolet of about 365 nanometers and mid-range ultraviolet of about 300 manometers are created by coating the inside of the fluorescent tubes with the proper phosphors which convert the short wave ultraviolet.

In the past ultraviolet irradiation of selected articles has been accomplished using a single UV range fluorescent tube mounted within a suitable enclosure. In order to eliminate white light generated by the UV tube, some prior art devices make use of a UV transmitting light blocking filter that is typically mounted in front of the UV tube.

In the past, when it was desired to obtain two UV wave lengths from the radiation device, two UV tubes emitting two levels of UV radiation were mounted side by side within the device, and an appropriate filter was placed in front of each tube.

In the apparatus disclosed in the previously identified U. S. Patent No. 5,175, 347 issued to the present inventor, a different and novel technique was used to irradiating an object, with ultraviolet radiation at a selected long, short or midwave length. More particularly, in this prior art apparatus, a plurality of ultraviolet sources, each emitting radiation at a different wave length, were mounted within a rotatable array so that a selected one of the sources could be moved into alignment with the specimen and automatically energized by merely rotating the array.

As will be better understood from the discussion that follows, the present in- vention enables the controlled irradiation of a specimen with UV at selected wavelengths through the use of a novel wavelength conversion means that can be interposed between the UV source and the specimen.

Summary of the Invention It is an object of the present invention to provide an apparatus for expeditiously irradiating an object with ultraviolet radiation at a selected UV wavelength.

More particularly, the apparatus of the invention comprises a plurality of ul- traviolet sources, each emitting radiation at a first wave length. The W sources are mounted within a housing that also supports a novel conversion plate that can be interposed between the UV sources and the specimen and functions to convert the UV to a second wavelength.

Another object of the invention is to provide an apparatus of the aforementioned character in which the conversion plate is slidably carried by the housing.

Another object of the invention is to provide an apparatus as described in the preceding paragraphs in which the specimen can be irradiated with ultraviolet radiation at a selected wave length between about 254 nanometers and about 365 nanometers.

Still another object of the invention is to provide an apparatus of the class described, which includes strategically located reflectors for reflecting the ultraviolet radiation in a direction toward the specimen. Another object of the invention is to provide an apparatus as described in the preceding paragraphs in which a filter for blocking white light from the UV sources is interposed between the specimen and the UV sources.

Yet another object of the invention is to provide an apparatus of the character described which is of a simple, compact construction that is easy to use and can be inexpensively manufactured.

Brief Description of the Drawings Figure 1 is a generally perspective view of one form of the apparatus of the invention for irradiating an object with ultraviolet radiation.

Figure 2 is a generally perspective, exploded view of the apparatus shown figure 1.

Figure 3 is a top plan view of the apparatus shown in figure 1.

Figure 4 is a cross-sectional to take along lines 4-4 figure 3.

Figure 5 is a side elevational view of the apparatus shown in figure 1.

Figure 6 is an end view of the apparatus shown in figure 1.

Figure 7 is a cross-sectional view taken along lines 7-7 of figure 6.

Figure 8 is a cross-sectional view taken along lines 8-8 of figure 5.

Figure 9 is a cross-sectional view taken along lines 9-9 in figure 5.

Figure 10 is a generally perspective view of an alternate form of the apparatus of the invention.

Figure 11 is a transverse, cross-sectional view of the form of the apparatus shown in figure 10.

Figure 12 is a cross-sectional view taken along lines 12-12 figure 11.

Figure 13 is a generally perspective, exploded view of the alternate form of the apparatus shown in figure 10.

Description of the Invention Referring to the drawings and particularly to figures 1 through 9, one form of the irradiation apparatus of the present invention is there illustrated and generally designated by the numeral 12. The apparatus of this form of the invention comprises a housing 14 having interconnected top, bottom and sidewalls 16,18, and 20 respectively that define an internal chamber 22. Carried by top wall 16 is filter means filter for blocking white light from the UV sources 24 that are disposed within internal chamber 22. The filter means here comprises a UV transmitting light blocking filter 26. Filter 26 is adapted to cant'an article, such as a specimen that is to be irradiated as, for example, a ploynucleocide. In the present form of the invention, filter 26 blocks white light.

As best seen in figure 2, the UV sources here comprises a plurality of spaced- apart, ultraviolet-light-emitting lamps 24a that emit UV radiation at a first wavelength of, for example, 254 nanometers. Positioned between the array of lamps 24a and filter 26 is the highly novel first wavelength conversion means of the invention which is adapted to convert the UV radiation at the first wavelength to UV radiation at a second wavelength of, for example, 365 nanometers. This first wavelength conversion means here comprises a conversion plate 28 that is removably carried by housing 14 at a location intermediate filter 26 and UV source 24. More particularly, plate 28 is provided with a wave shifting phosphor coating 30 (figures 4 and 7) and is slidably movable within a slot 32 formed in housing. With this construction, plate 28 can be readily removed from the housing and replaced with another plate if desired. As is well known in the art, phosphors are compounds that are capable of emitting useful quantities of radiation in the visible and/or ultraviolet spectrums upon excitation of the material by an external energy source. Due to this property, phosphor compounds have long been utilized in cathode ray tube (CRT) screens for televisions and similar devices. Typically, inorganic phosphor compounds include a host material doped with a small amount of an activator ion. In recent years, phosphor compounds, including phosphors in particulate form, have been used in display devices, decorations, cathode ray tubes, and fluorescent lighting fixtures. Luminescence or light emission by phosphor particles may be stimulated by application of heat (thermoluminescence), light (photoluminescence), high energy <BR> <BR> radiation (e. g. , x-rays or e-beams), or electric fields (electroluminescence). A comprehensive discussion of various types of phosphors can be found in Patent No.

6,193, 908 issued to Hampden-Smith et al.

Turning to figures 10 through 13, an alternate form of transilluminator of the invention is there shown. This form of the invention is similar in many respects to that shown in figures 1 through 9 and like numerals are used in figures 10 through 13 to identify like components. This alternate form of the invention comprises a housing. 34 having interconnected top, bottom and sidewalls 36,38, and 40 respectively that define an internal chamber 42. Carried by top wall 36 is filter means filter for blocking white light from the UV sources 24 that are disposed within internal chamber 42. The filter means here comprises a UV transmitting light blocking filter 26. As before, filter 26 is adapted to carry an article, such as a specimen that is to be irradiated.

As best seen in figure 11, the UV sources here comprises a plurality of spaced- apart, ultraviolet-light-emitting lamps 24a that emit UV radiation at a first wavelength of, for example, 254 nanometers. Lamps 24a are here positioned over a corrugated reflector 45. Positioned between the array of lamps 24a and filter 26 are first and second wavelength conversion means which are adapted to convert the UV radiation at the first wavelength to UV radiation at a second wavelength of, for example, 300 nanometers and then to UV radiation at a third wavelength of, for example, 365 nanometers. This first wavelength conversion means here comprises a first conversion plate 48 that is removably carried by housing 34 within a slot 49 at a location intermediate filter 26 and UV source 24. In this instance, plate 48 is provided with a wave shifting phosphor coating 50 (figures 11 and 12) and is slidably movable within the slot 49 that is formed in housing. The second wavelength conversion means of this latest form of the invention comprises a second conversion plate 54 that is also removably carried by housing 34 within slot 49. Plate 54 is provided with a wave shifting phosphor coating 56 (figures 11 and 12) and is slidably movable within the slot 49. Plate 54 is disposed at a location intermediate plate 48 and filter 26 in the manner shown in the drawings. With the con- struction shown, either or both plates 48 and 54 can be readily removed from the housing and replaced with alternate plates if desired.

Having now described the invention in detail in accordance with the requirements of the patent statutes, those skilled in this art will have no difficulty in making changes and modifications in the individual parts or their relative assembly in order to meet specific requirements or conditions. Such changes and modifications may be made without departing from the scope and spirit of the invention ; as set forth in the following claims.