|Número de publicación||WO1995033972 A1|
|Tipo de publicación||Solicitud|
|Número de solicitud||PCT/US1995/006127|
|Fecha de publicación||14 Dic 1995|
|Fecha de presentación||12 May 1995|
|Fecha de prioridad||2 Jun 1994|
|Número de publicación||PCT/1995/6127, PCT/US/1995/006127, PCT/US/1995/06127, PCT/US/95/006127, PCT/US/95/06127, PCT/US1995/006127, PCT/US1995/06127, PCT/US1995006127, PCT/US199506127, PCT/US95/006127, PCT/US95/06127, PCT/US95006127, PCT/US9506127, WO 1995/033972 A1, WO 1995033972 A1, WO 1995033972A1, WO 9533972 A1, WO 9533972A1, WO-A1-1995033972, WO-A1-9533972, WO1995/033972A1, WO1995033972 A1, WO1995033972A1, WO9533972 A1, WO9533972A1|
|Inventores||Daniel Richard Klemer, Pliny Scott Hawthorn|
|Solicitante||Spectra-Physics Laserplane, Inc.|
|Exportar cita||BiBTeX, EndNote, RefMan|
|Citas de patentes (3), Citada por (13), Clasificaciones (3), Eventos legales (4)|
|Enlaces externos: Patentscope, Espacenet|
LASER ALIGNMENT DEVICE AND METHOD USING GREEN LIGHT
Background of the Invention
The present invention generally relates to laser-based alignment systems which generate reference beams of light and, more particularly, to a laser alignment system and method wherein a beam of light in the green portion of the optical spectrum is provided as a reference.
Systems employing a reference beam of light have been used in numerous interior construction applications. In particular, such systems have been advantageously used to set wall moldings, main runners and cross runners. Prior to actual construction, such laser alignment systems can be used to check for low hanging ducts, sprinklers or other obstacles. The laser alignment systems have also been used to transfer reference lines from floors to ceilings and locate upper and lower partition tracks, overhead drop walls and bulkheads. In short, laser alignment systems have been used in numerous applications to provide reference positions during interior construction.
One such system is disclosed in commonly assigned U.S. Patent No. 4,221,483 issued to Rando, the disclosure of which is hereby incorporated by reference. Rando discloses a laser beam level instrument having a solid state light source and a pendulous, positive lens which provides self-leveling within a limited range. A multiple reference laser beam transmitter is disclosed in commonly assigned U.S. Patent No. 4,676,598 issued to Markley et al. which is hereby incorporated by reference. The Markley et al. transmitter simultaneously generates a stationary reference beam of light and a moving reference beam of light. The moving beam rotates in a plane normal to the stationary beam.
The reference beam of light may be viewed on the objects to be aligned, on a visual optical target, or on an active optical target. Examples of such active optical targets are disclosed in commonly assigned U.S. Patent Nos. 4,907,874 and 5,095,629, the disclosures of which are hereby incorporated by reference. Each optical target detects and displays the position of the reference beam of light with respect to the target. Thus, a worker can use the optical target in conjunction with the reference beam of light to position walls, moldings and the like.
Typically, such laser alignment systems have primarily employed gas or semiconductor lasers which emit light in the red portion of the optical spectrum (approximately 630-700 nm) . Consequently, the optical targets have heretofore been designed to detect incident light in the red portion of the optical spectrum. However, the use of light in the red portion of the optical spectrum has created various problems. For instance, high power levels are needed to emit a red light beam with sufficient brightness to be readily viewed by the human eye. Power levels which are too high can be hazardous to operators of the system. For instance, prolonged exposure to high powered laser beams may result in various eye injuries. In view of the potential health hazards, federal and international regulatory agencies have strictly regulated the construction and use of lasers. These regulations, although beneficial to the health of laser users, severely restrict the maximum power of lasers which may be employed in laser alignment systems. This, in turn, has limited the useful operating ranges of prior alignment systems. In addition, it has been found that the use of a red light beam restricts the useful range of the laser alignment system for another reason. During light beam propagation, the diameter of the beam enlarges in proportion to both distance and wavelength. Since red light has the longest wavelength of any visible light, it necessarily experiences a large amount of diffraction divergence over distance. Consequently, the alignment accuracy of a laser alignment system using a red light beam is limited by this widening of the beam.
For the foregoing reasons, there is a need for a laser alignment system and method utilizing a low powered light source which is operable over greater distances, and in which diffraction divergence is reduced to allow more accurate alignment. Summary of the Invention
This need is met by the laser alignment system and method of the present invention which uses a reference beam of light having wavelengths substantially in the green portion of the optical spectrum as a reference position.
In accordance with one aspect of the present invention, a laser alignment system includes a laser transmitter which generates a reference beam of light along a predetermined path. The reference beam of light has wavelengths substantially in the green portion of the optical spectrum. The laser transmitter may generate a stationary reference beam of light, a rotating reference beam of light or both. Preferably, the wavelengths of the beam of light are between 510 nanometers and 570 nanometers. The reference beam of light may be generated by a solid-state laser, a frequency- doubled solid-state laser, a gas laser such as a HeNe laser, a semiconductor laser diode or any other laser which can produce light in the green portion of the optical spectrum.
A laser receiver receives the reference beam of light and indicates the relative position of the reference beam of light on the laser receiver to assist in aligning ceilings, beams and other objects. Preferably, the laser receiver includes a green light detector for detecting light of the wavelength produced by the transmitter. The Green light detector may include tinted glass which filters non-green light wavelengths. For ease of use, the laser receiver may include an indicator for indicating, either visually or audibly, the relative position of the reference beam of light on the laser receiver.
In accordance with another aspect of the present invention, a method for defining a reference position in a construction site is disclosed. The method comprises the steps of: providing a laser transmitter for generating a reference beam of light at' a known relationship to the reference position, the reference beam of light having wavelengths substantially in the green portion of the optical spectrum; and using the reference beam of light as the reference position during construction. The step of using the reference beam of light may comprise the steps of: providing a laser receiver for determining the relative position of the reference beam of light; and using the laser receiver to determine the position of the reference beam of light.
Accordingly, it is an object of the present invention to provide an improved laser alignment system and method utilizing a low powered light source which is operable over greater distances, and in which diffraction divergence is reduced to allow more accurate laser alignment of objects during a construction project.
Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims. Brief Description of the Drawings
Fig. 1 is a perspective view of an exemplary laser transmitter in accordance with the present invention; Fig. 2 is a front view of an optical target which may be used in conjunction with the laser transmitter to detect the position of a beam of light in accordance with the present invention; and
Fig. 3 is a graphical representation of the relationship between the visibility of a beam of light at distance and the wavelength of the beam of light. Detailed Description of the Invention
A laser alignment system in accordance with the present invention consists of a laser transmitter 100, shown in Fig. 1, and a laser receiver 200, shown in Fig. 2. The laser transmitter 100 simultaneously generates a stationary reference beam of light 102 and a moving reference beam of light 104. The moving beam of light 104 rotates in a plane generally normal to the stationary reference beam 10.2. The laser transmitter 100 is similar to that disclosed in U.S. Patent No. 4,676,598 issued to Markley et al. which has been incorporated by reference herein. It should be understood that the laser transmitter 100 is exemplary and any laser transmitter which produces one or more reference beams of light may be advantageously employed in .the present invention.
Housing 106 of the laser transmitter 100 includes a laser source which produces a beam of light having wavelengths substantially in the green portion of the optical spectrum. As is well known, green light generally has wavelengths between 510 nanometers and 570 nanometers. The laser source may be any of a number of designs which produce green light. For example, the laser source may be a frequency-doubled solid-state laser, a gas laser such as a helium-neon green laser or a semiconductor green laser diode. One particularly suitable laser source, for example, is disclosed in U.S. Patent Application Serial No. 08/253,072 filed June 2, 1994, entitled "SOLID-STATE LASER" by Sobottke, et al. , the disclosure of which is hereby incorporated by reference. The relative response of the human eye to the visible wavelengths of light has been well documented. Generally, the overall brightness of a laser beam at working distances beyond the beam's Rayleigh range is given by the equation:
B(P,λ) = K • P • V(λ) λ"2
wherein V(λ) is the relative spectral response of the human eye, λ is the beam wavelength, K is a constant of proportionality and P is beam power. A graphical representation of the relationship between visibility at distance and wavelength is shown in Fig. 3. The graph has been normalized such that the visibility (or brightness) of a laser with a wavelength of 633 nm (red) has a value of 1. As is apparent from Fig. 3, a laser operating between 525 and 570 nm (green) requires approximately one-fifth the power of a laser operating at 633 nm (red) to appear equally as bright.
Referring now to Fig. 1, the stationary reference beam 102 emerges through an opening 108 in a cap plate 110 of the transmitter 100. Moving reference beam 104 passes through glass windows 112 positioned around the circumference of the housing 106. Since the structure and philosophy of the internal operation of the laser transmitter are not important to the present invention beyond the generation of a reference beam of light in the green portion of the optical spectrum, they will not be further described herein.
When aligning an object with a reference beam of light, the reference beam may be viewed directly on the object or on the laser receiver 200. The laser receiver 200 includes a photodetector assembly which detects a beam of light incident to a window or aperture 202 defined by the transmitter case 204, as shown in Fig. 2. A control knob 205 operates the power to the receiver 200. A green light detector 206 is provided to enhance the contrast of the green reference beam of light against ambient light. The green light detector 206 may consist of a substantially transparent material having a green tint which is transparent to light in the green portion of the optical spectrum. Numerous tinted materials for filtering particular wavelengths are well known in the art and, therefore, will not be further discussed hereinafter.
An indicator, shown as display 208, visually indicates the relative position of the incident reference beam of light on the window 202. Specifically, the display 208 indicates whether the light is above, below or within a reference band centered in the window 206. The display 208, which may for example be an LCD display, includes a pair of arrows 210, 212 and a bar 214. Arrows 210, 212 are displayed if the reference beam is below or above the reference band. Bar 214 is displayed if the reference beam is within the reference band. The structure and philosophy of the internal operation of the laser receiver 200 is fully described in U.S. 4,907,874 which was previously incorporated by reference and, therefore, will not be discussed herein. Moreover, it should be understood that the laser receiver shown in Fig. 2 is exemplary and any laser receiver which detects the relative position of a reference beam of light may be advantageously employed in the present invention.
A method for defining a reference position during construction in accordance with the present invention will now be described. During construction, the laser transmitter is positioned so as to generate one or more reference beams of light at known relationships to the reference position. To increase accuracy and reduce the power levels, the reference beams of light have wavelengths in the green portion of the optical spectrum. Thereafter, the reference beams of light are used as a reference position in positioning objects during construction. A laser receiver may be used to determine the relative position of the reference beams of light when positioning objects relative to the reference beams. The laser receiver preferably enhances light substantially in the green portion of the optical spectrum.
Having thus described the invention in detail by reference to preferred embodiments thereof, it will be apparent that other modifications and variations are possible without departing from the scope of the invention defined in the appended claims.
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|29 Feb 1996||DFPE||Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)|
|3 Abr 1996||121||Ep: the epo has been informed by wipo that ep was designated in this application|
|17 Sep 1997||122||Ep: pct application non-entry in european phase|