Optics: measuring and testing – By dispersed light spectroscopy – Utilizing a spectrometer
Reexamination Certificate
2002-01-31
2004-08-24
Smith, Zandra V. (Department: 2877)
Optics: measuring and testing
By dispersed light spectroscopy
Utilizing a spectrometer
C356S328000
Reexamination Certificate
active
06781691
ABSTRACT:
BACKGROUND
Light bulbs usually provide light that includes all the colors in the rainbow: violet, blue, green, yellow, orange, and red. When all of these colors are present, the light is known as “white light.” The rainbow, which is the separated colors, is known as a spectrum. Different kinds of light bulbs provide different quantities of the various colors, which means, for example, that some light bulbs provide more red light than blue light, while other light bulbs provide more green light than orange light. In addition, most light bulbs also provide light that is not visible to the naked eye, such as ultraviolet (UV) light and infrared (IR) light.
The different colors of light are known as different wavelengths of light, and range in the visible spectrum from violet or blue light having a wavelength of about 400 nm to red light having a wavelength of about 700 nm; UV light is typically between about 300 nm to 400 nm, and IR light is typically from about 700 nm to 1000 nm.
For a long time, people have wanted to select specific wavelengths and/or intensities of light for specific situations, such as for lighting a movie scene so that it looks like the middle of a bright summer day in Mexico City or a cool fall evening with a beautiful sunset in Anchorage, Ak., for diagnosing or treating disease, for measuring or analyzing the chemical or physical properties of an object, or for initiating a physical or chemical change in an object or compound or organism.
In order to obtain particular wavelengths and intensities of light, movie sets employ highly skilled and specialized lighting technicians that use very expensive light bulbs, lighting apparatus, lighting filters (such as colored “gels”), and the like. The intense heat generated by the lights, however, reaches oven-like temperatures and can cook film, filters, and lighting elements. Other situations likewise employ expensive personnel and apparatus.
In some previous attempts to deal with these problems, a spectrum former, such as a prism, has been placed in front of the light bulb to separate the light beam into its respective wavelengths, then a transmissive pixelated spatial light modulator has been placed in the spectrum. A pixelated spatial light modulator is typically a square or rectangular device (although other shapes are possible) that contains a large number of tiny pixels and can be turned on or off at will. Turning a line of pixels “on” while turning all others “off” permits the spatial light modulator to pick a specific color of light; more complex on/off patterns can pick more complex wavelength and intensity distributions. However, these prior attempts have been problematic because the pixelated spatial light modulators have either absorbed the undesired light or reflected it back to the original light source or spectrum former. In either case, the heat from the undesired light is not dissipated and serious problems may ensue.
Thus, there has gone unmet a need for lighting systems and luminaires that provide selected light wavelengths and intensities but that do not overheat, and that can also rapidly switch between different selected wavelengths or intensities, including highly complex groupings of wavelengths or intensities. The present invention provides these and other advantages.
SUMMARY
The present invention provides lighting systems that provide virtually any desired color(s) and intensity(s) of light, from white light to light containing only a certain color(s) and intensity(s). The colors, or “spectral output,” which means a particular wavelength, band of wavelengths, or set of wavelengths, as well as the intensities, which means a “wavelength dependent intensity distribution,” can be combined and varied as desired. The lighting systems avoid overheating problems and can be part of other systems or stand alone units such as luminaires (for example, the high-output lighting units used to illuminate movie scenes, concert stages, and night-time construction sites). The systems can provide any desired light, such as UV light, visible light, and infrared light.
The lighting systems are a low cost, effective approach to providing carefully controlled light for a variety of purposes such as medicine, movies, theater, photography, and sports. For example, the light can be selected to substantially mimic light such as high noon in New York City, or the light necessary to diagnose or treat cancer. Additionally, the lighting can be rapidly switched from one desired scenario to another without moving major parts of the system.
The lighting systems typically comprise a spectrum former upstream from a reflective pixelated spatial light modulator (SLM). The spectrum former accepts a light beam from a light source and turns it into a spectrum, and the spectrum is then transmitted to the SLM, such as a digital micromirror device (DMD). The SLM reflects substantially all of the light impinging on the SLM into at least two different light paths that do not reflect back to the light source or the spectrum former. At least one of the light paths acts as a projection light path and transmits desired light out of the lighting system or luminaire. The other light path can act as a repository for the reflected energy, an alternate projection light path, and/or a detection light path wherein a detector measures the light reflected from the pixelated SLM to determine whether the light has the desired wavelength and intensity characteristics. Because the mirrors in the pixelated SLM can be rapidly switched back and forth between different light paths, the reflected light beam that contains the desired wavelength and intensity distribution(s) can be alternated back and forth between a projection light path and detection light path. If desired, one or more additional pixelated spatial light modulators can be provided in one or more of the light paths, to provide further enhanced specificity and preciseness in the wavelength and intensity distributions or other added benefits.
The pixelated SLM may be operably connected to a controller, which controller contains computer-implemented programming that controls the on/off pattern of the pixels in the pixelated SLM. The controller can be located in any desired location to the rest of the system. For example, the controller can be either within a housing of the luminaire or it can be located remotely, connected by a wire, cellular link or radio link to the rest of the system. If desired, the controller, which is typically a single computer but can be a plurality of linked computers, a plurality of unlinked computers, computer chips separate from a full computer or other suitable controller devices, can also contain one or more computer-implemented programs that provide specific lighting characteristics, i.e., specific desired, selected spectral outputs and wavelength dependent intensities, corresponding to known light sources such as commercial light sources, specific natural lighting situations, such as afternoon at a particular longitude, latitude, time of day and cloudiness, or a specific light for disease diagnosis or treatment, or to invoke disease treatment (for example by activating a drug injected into a tumor in an inactive form), or other particular situations.
In one aspect, the present invention provides a lighting system that provides a variable selected spectral output and a variable wavelength dependent intensity distribution. The lighting system comprising a light path that comprises: a) a spectrum former able to provide a spectrum from a light beam traveling along the light path, and b) a reflective pixelated spatial light modulator located downstream from and optically connected to the spectrum former, the reflective pixelated spatial light modulator reflecting substantially all light impinging on the reflective pixelated spatial light modulator and switchable to reflect light from the light beam between at least first and second reflected light paths that do not reflect back to the spectrum former. The reflective pixelated spatial light modulator can be a digital mi
MacAulay Calum E.
MacKinnon Nicholas B.
Stange Ulrich
Graybeal Jackson Haley LLP
Smith Zandra V.
Tidal Photonics, Inc.
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