Optical: systems and elements – Absorption filter – Neutral or graded density
Reexamination Certificate
1998-10-27
2001-07-24
Buczinski, Stephen C. (Department: 3662)
Optical: systems and elements
Absorption filter
Neutral or graded density
C065S037000
Reexamination Certificate
active
06266198
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to laser transceivers, and more particularly to methods and apparatus for testing, aligning, and refurbishing laser transceivers.
Today, laser radar (LADAR) and other systems incorporating laser transmit-and-receive devices are in widespread use. For example, laser transceivers are routinely employed in military applications for such purposes as target detection, acquisition, identification and tracking. However, due to the inherent high-precision nature of laser systems, testing and alignment of laser transceiver units can be difficult. Indeed, except for the simple adjustment of transceiver mounting screws or the wholesale replacement of peripheral receiver assemblies, failed laser transceivers are conventionally returned to the transceiver supplier for repair and maintenance. The supplier can provide both the facilities and the skill required to carry out high-precision laser alignment and testing.
However, because the delays associated with shipping a laser transceiver unit to and from an appropriate supplier can be quite long, and because laser system suppliers typically have significant repair backlogs, conventional laser transceiver repair and maintenance is extremely costly in terms of both time and money. As a result, laser system users often keep a large number of laser transceiver spares on hand. The cost of doing so, however, can be prohibitive. Thus, there is a need for improved methods and apparatus for testing, aligning and refurbishing laser transceivers. In particular, there is a need for methods and apparatus allowing a relatively unskilled technician, who can be located nearer the system user, to perform advanced laser maintenance and refurbishment. Such methods and apparatus will yield significant improvements in terms of laser repair cost and turnaround time and will greatly enhance user self-sufficiency.
SUMMARY OF THE INVENTION
The present invention fulfills the above-described and other needs by providing a consolidated laser alignment and test station which enables a technician having relatively little specialized training to quickly perform advanced laser repair and maintenance procedures. The test station utilizes recent developments in electro-optic technologies to put all of the resources necessary for dynamically testing and aligning a laser transceiver unit within arm's reach of a single operator. Thus, the test station provides a high level of system repair through-put at significantly reduced cost.
In exemplary embodiments, equipment sufficient to dynamically test and align NdYAG laser transceiver units is provided on a single compact bench. Thus; according to the present invention, cavity-box efficiency testing, dynamic open-interferometer alignment, dynamic open-case alignment, closed-case laser boresighting, and complete laser functionality and diagnostic testing can be carried out at a single station. Real-time user feedback is provided so that high-precision laser alignments and repairs can be made quickly and cost effectively.
According to the present invention, a customized test fixture is used to mount the cavity box and interfrometer of a laser transceiver unit under test to the test station bench. Thus, the cavity box and interferometer are mounted external to the laser transceiver unit case so that full-access laser-optics adjustments can be made. Additionally, a virtual laser bed fixture can be mounted in place of the laser transceiver unit interferometer to permit direct testing of the cavity box assembly itself. Furthermore, the entire closed-case laser transceiver unit can be mounted on the test station bench for final adjustments and boresighting of the laser transmitter and receiver. Generally, laser transceiver unit laser-optics adjustments are made while critical laser functions are simultaneously monitored via discrete test station readouts relating to beam quality, radiometry, and temporal behavior.
In exemplary embodiments, two cameras provide far-field, near-field, wide-field and receiver-field beam viewing. The novel two-camera combination allows a test station operator to efficiently view, measure, analyze and adjust a laser transceiver unit at all levels of operation. One of the cameras is combined with a pin-hole lens and a quad step-filter optic attenuator to form a wide-field beamfinder assembly. Using the beamfinder assembly in conjunction with self-contained alignment optics included with the text fixtures described above, a test station operator can quickly align the laser to the second camera. The second camera then provides both near-field and far-field beam viewing, while a radiometer and a pulse detector provide additional diagnostics. In exemplary embodiments, the beamfinder assembly also provides receiver-field laser viewing to allow for rapid boresight adjustments.
Advantageously, the modular and highly flexible design of the test station allows it to be rapidly reconfigured to align and test a wide variety of laser transceiver units. For example, with appropriate optic interface fixtures and suitable cameras, the test station can accommodate NdYAG lasers operating at 1.064 &mgr;m, 0.532 &mgr;m, or 1.54 &mgr;m (Raman or wavelength shifted 1.064 &mgr;m) wave-lengths. Additionally, dual wavelength lasers (i.e., 1.5/1.064 &mgr;m) can be aligned and tested using an appropriate collimator mirror and bolt-in dual-camera modules. Radiometry and image processing components of the test station automatically reconfigure to the laser transceiver unit under test. Because virtually any dynamic adjustment of a laser transceiver unit under test can be performed at a single test station, laser testing and alignment can be conducted in a quick and cost-effective manner. Additionally, because the test station diagnostics provide straightforward real-time feedback, laser repair and maintenance can be achieved by a relatively inexperienced technician.
The above described and additional features of the present invention are explained in greater detail hereinafter with reference to the illustrative examples shown in the accompanying drawings. Those skilled in the art will appreciate that the described embodiments are provided for purposes of illustration and understanding and that numerous equivalent embodiments are contemplated herein.
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Buczinski Stephen C.
Burns Doane , Swecker, Mathis LLP
Lockheed Martin Corporation
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