Abstract: An external cavity laser has a wavelength of the laser output that is tuned by a rotary tuning element mounted on the axle of a motor. The rotary tuning element includes a variable thickness interference film for wavelength selection, and a variable thickness compensation prism to adjust the cavity length appropriately for the selected wavelength, to stable wavelengths and mode-hop-free tuning ranges as the tuning element is rotated.

Abstract: An interferometric fiber optic encoder readhead for sensing the displacement of a scale grating is disclosed. The detector channels of the readhead are fiber optic detector channels having respective phase grating masks. The fiber optic encoder readhead is configured to detect the displacement of interference fringes arising from the scale grating. In various exemplary embodiments, the fiber optic readhead is constructed and operably positioned according to various design relationships that insure a compact mounting and a relatively ideal sinusoidal signal as a function of displacement. Accordingly, high levels of displacement signal interpolation may be achieved, allowing sub-micrometer displacement measurements. The fiber optic encoder readhead may be assembled in a particularly accurate and economical manner and may be provided in a package with dimensions on the order of 1–2 millimeters.

Abstract: A 2D fiber optic encoder readhead having multiple readhead portions for sensing the two-dimensional displacement of a scale grating is disclosed. The detector channels of the readhead portions are fiber optic detector channels having respective phase grating masks. At least two of the phase grating masks have different orientations so as to facilitate the detection of displacement in at least two different directions. The 2D fiber optic encoder readhead portions are configured to detect the displacement of a self-image pattern that results from a corresponding pattern on the scale grating. The self-image pattern allows for the detection of displacement in the at least two different directions. In various exemplary embodiments, the fiber optic readhead portions are constructed according to various design relationships that insure a robust signal-to-noise ratio. Accordingly, high levels of displacement signal interpolation may be achieved.

Abstract: A method and apparatus for measuring a wavelength-related characteristic of a radiation source is provided. Two beams travel through substantially identical filters at different angles, which produces two different output signals that behave similarly with respect to power and/or temperature variations. In various embodiments, the two beams are filtered through two portions of a single filter. A diffraction grating may be mounted to the filter to split incident radiation into first and second beams. The beams thus travel through the filter at different angles, to produce two output signals that can be combined to compensate for common-mode errors as well as power variations. Extremely small size and high-resolution may be achieved. Single or multiple detectors may also be used.

Abstract: An absolute position fiber optic encoder readhead having multiple readhead portions for sensing the displacement of respective scale grating tracks of a scale is disclosed. The detector channels of the readhead portions are fiber optic detector channels having respective phase grating masks. The fiber optic encoder readhead portions are configured to detect the displacement of a self-image of a respective scale grating track of the scale. In various exemplary embodiments, the fiber optic readhead portions are constructed according to various design relationships that provide a relatively high signal-to-noise ratio. Accordingly, high levels of displacement signal interpolation may be achieved, allowing submicrometer displacement measurements.

Abstract: A fiber optic readhead arrangement for imaging a scale onto a set of optical fiber receiver channels is disclosed. The readhead arrangement includes an imaging lens and may include an aperture positioned at a focal point of the imaging lens in a telecentric arrangement. An axicon lens may be utilized to direct source light away from the imaging lens and into a ring-shaped annular source lens which surrounds the imaging lens. A source lens may concentrate source light on the scale in an area where it will be imaged back through the imaging lens to the readhead. In one embodiment, multiple source fibers may be provided around the perimeter of the fiber optic readhead arrangement. In another embodiment, the receiver fibers may also function as source fibers. In various exemplary embodiments, high levels of displacement signal interpolation may be achieved to provide high resolution measurement.

Abstract: A fiber optic encoder readhead for sensing the displacement of a scale grating is disclosed. The detector channels of the readhead are fiber optic detector channels having respective phase grating masks. The fiber optic encoder readhead is configured to detect the displacement of a self-image of the scale grating. In various exemplary embodiments, the fiber optic readhead is constructed according to various design relationships that insure a robust signal-to-noise ratio. Accordingly, high levels of displacement signal interpolation may be achieved, allowing sub-micrometer displacement measurements. The fiber optic encoder readhead may be assembled in a particularly accurate and economical manner and may be provided in a package with dimensions on the order of 1-2 millimeters.

Abstract: An integrated imaging element for an interferometer generates at least one image that includes multiple interference portions with different relative phase shifts interleaved in a pattern having a high spatial frequency in the image. The interleaved pattern is at least partially determined by the pattern of a high density polarizing array used in the integrated imaging element. In various embodiments, the multiple interference portions are interleaved in a checkerboard pattern across the entire surface of a detector device. As a result, various non-common mode errors present in various interferometers that generate separate non-interleaved images for each relative phase are reduced or eliminated because multiple phase-shifted interference image information for a small region of an object is provided within a small region on the detector device.

Abstract: An integrated imaging element for an interferometer generates at least one interference image that includes multiple interference portions with different relative phase shifts interleaved in a pattern having a high spatial frequency in the image. The interleaved pattern is at least partially determined by the pattern of a high density relative retarder array used in the integrated imaging element. In various embodiments, the multiple interference portions are interleaved in a checkerboard-like pattern across the entire surface of a detector device. As a result, various non-common mode errors present in various interferometers that generate separate non-interleaved images for each relative phase are reduced or eliminated.

Abstract: A 2D fiber optic encoder readhead having multiple readhead portions for sensing the two-dimensional displacement of a scale grating is disclosed. The detector channels of the readhead portions are fiber optic detector channels having respective phase grating masks. At least two of the phase grating masks have different orientations so as to facilitate the detection of displacement in at least two different directions. The 2D fiber optic encoder readhead portions are configured to detect the displacement of a self-image pattern that results from a corresponding pattern on the scale grating. The self-image pattern allows for the detection of displacement in the at least two different directions. In various exemplary embodiments, the fiber optic readhead portions are constructed according to various design relationships that insure a robust signal-to-noise ratio. Accordingly, high levels of displacement signal interpolation may be achieved.

Abstract: An absolute position fiber optic encoder readhead having multiple readhead portions for sensing the displacement of respective scale grating tracks of a scale is disclosed. The detector channels of the readhead portions are fiber optic detector channels having respective phase grating masks. The fiber optic encoder readhead portions are configured to detect the displacement of a self-image of a respective scale grating track of the scale. In various exemplary embodiments, the fiber optic readhead portions are constructed according to various design relationships that provide a relatively high signal-to-noise ratio. Accordingly, high levels of displacement signal interpolation may be achieved, allowing submicrometer displacement measurements.

Abstract: An integrated imaging element for an interferometer generates at least one interference image that includes multiple interference portions with different relative phase shifts interleaved in a pattern having a high spatial frequency in the image. The interleaved pattern is at least partially determined by the pattern of a high density relative retarder array used in the integrated imaging element. In various embodiments, the multiple interference portions are interleaved in a checkerboard-like pattern across the entire surface of a detector device. As a result, various non-common mode errors present in various interferometers that generate separate non-interleaved images for each relative phase are reduced or eliminated.

Abstract: An integrated imaging element for an interferometer generates at least one image that includes multiple interference portions with different relative phase shifts interleaved in a pattern having a high spatial frequency in the image. The interleaved pattern is at least partially determined by the pattern of a high density polarizing array used in the integrated imaging element. In various embodiments, the multiple interference portions are interleaved in a checkerboard pattern across the entire surface of a detector device. As a result, various non-common mode errors present in various interferometers that generate separate non-interleaved images for each relative phase are reduced or eliminated because multiple phase-shifted interference image information for a small region of an object is provided within a small region on the detector device.

Abstract: A method and apparatus for measuring a wavelength-related characteristic of a radiation source is provided. Two beams travel through substantially identical filters at different angles, which produces two different output signals that behave similarly with respect to power and/or temperature variations. In various embodiments, the two beams are filtered through two portions of a single filter. A diffraction grating may be mounted to the filter to split incident radiation into first and second beams. The beams thus travel through the filter at different angles, to produce two output signals that can be combined to compensate for common-mode errors as well as power variations. Extremely small size and high-resolution may be achieved. Single or multiple detectors may also be used.

Abstract: A fiber optic encoder readhead for sensing the displacement of a scale grating is disclosed. The detector channels of the readhead are fiber optic detector channels having respective phase grating masks. The fiber optic encoder readhead is configured to detect the displacement of a self-image of the scale grating. In various exemplary embodiments, the fiber optic readhead is constructed according to various design relationships that insure a robust signal-to-noise ratio. Accordingly, high levels of displacement signal interpolation may be achieved, allowing sub-micrometer displacement measurements. The fiber optic encoder readhead may be assembled in a particularly accurate and economical manner and may be provided in a package with dimensions on the order of 1-2 millimeters.