Abstract: A position determining system (PDS)(100) or multiple parameters measurement system (MPMS)(300) particularly useful for translation and rotation measurement of objects having up to five degrees of freedom. A light source (122, 302) provides light beams (124, 304) into at least two channels. Each channel may include an interferometer (310), reflective target (110, 314), beam splitter (128, 312), detector (132, 316), and receiver (318). In concert, the detectors (132, 316) sense horizontal, vertical, and roll position and the receivers (318) sense longitudinal and yaw position change. Optionally, modulation can be imposed on the light beams (124, 304) and phase-sensitive synchronous demodulation used to enhance accuracy.

Abstract: A servo track writing apparatus (10) for writing servo tracks (16) on a media disk (14) of a disk drive assembly (12) having a Positioning arm (22) with a through hole (28) therein. The writing apparatus (10) has a laser source (29) which directs a source beam (30) through a polarizing beam splitter (32) and a quarter-wave plate (34) to either pass through the through hole (28) and reflect off of the media disk (14) as a reflected beam (38), or to be reflected from regions of the positioning arm (22) proximate to the through hole (28) as a reflected beam (56). The writing apparatus (10) further has a remote tracking arm (42) with two photodiodes (40a, 40b) suitably mounted thereon to receive the reflected beams (38, 56). The tracking arm (42) is caused by a motive means (54) to precisely track the positioning arm (22) of the disk drive assembly (12).

Abstract: The present invention is a laser system (10, 100, 200) employing paired simple lasers (12, 16) or paired Zeeman type lasers (102, 112 or 202, 204). Systems of beambenders (20, 108, 210, 212, 214), half-wave plates (106, 116), and polarizing beamsplitters (22, 104, 114, 118, 216) pair the frequency component of one laser (12, 16, 102, 112, 202, 204) with that of another to produce one or more measurement beams (24, 150, 160, 228, 230) having orthogonally polarized frequency components. Systems of beamsplitters (26, 120, 124, 218, 220) and photodetectors (30, 122, 126, 206, 208) provide reference information about the frequency difference (196, 198) between the respective frequency components in the measurement beams (24, 150, 160, 228, 230). The frequency difference (196, 198) is tunable across a wide range, specifically including 4 MHz to 40 MHz when the lasers (12, 16, 102, 112, 202, 204) are conventional He--Ne types.

Abstract: The present invention is a laser (12) having a resonator (28) between an output coupling mirror (20) and a high-reflection mirror (26). A photoelastic plate (38) is incorporated in a photoelastic cell (24), or a photoelastic mirror (36) used in place of the high-reflection mirror (26). The photoelastic plate (38) is placed in the resonator (28) and introduces an artificial anisotropy to the laser (12). The photoelastic plate (38) has privileged directions (34), which are aligned with the axes of the artificial anisotropy. A magnetic field (32) is applied transversely to the resonator (28), in alignment with one of the privileged directions (34), to produce two orthogonal linearly polarized frequencies in an output beam (30) with the Zeeman effect.

Abstract: An environmental metrology device (10) containing sensor (12) elements which include a pressure sensor (20), a temperature sensor (22), and a humidity sensor (24) all located in close proximity within a housing (18). Control circuitry (16) is further provided to direct operation of the sensors (12) and to communicate with an interferometer controller (42) via a signal port (14) and a cable (92). Additional instances of the device (10) may be connected in a daisy-chain network configuration via additional signal ports (14) and cables (90). One or more instances of the device (10) permit highly localized characterization of atmospheric index of refraction in the measurement region (60) of a laser interferometer (30). The interferometer controller (42) is thereby able to compensate measurements performed by the laser interferometer (30) before they are passed onto manufacturing process controls (48).

Abstract: A servotrack writing apparatus (10) having a reference section (30), a workpiece section (32), and a tracking section (34). With the reference section (30) a standard is established without a disk drive workpiece (12) mounted. A workpiece (12) is then mounted in the workpiece section (32) with a beamsplitter-reflector unit (52) attached to the actuator arm (20) bearing the read-write head (18) which is to be used for servotrack writing, and verification information is obtained for comparison with the standard. Based upon this comparison, correction of workpiece (12) mounting offset and eccentricity of beamsplitter-reflector unit (52) mounting may then be performed before servotracks are written, or compensation for such offset and eccentricity may be performed while servotracks are written.

Abstract: An improved laser refractometer (10) employing a interferometer optical component (12), an object mirror (14) and an etalon (16). The etalon (16) is moved in the path of a plurality of reference beams (22, 24) and a plurality of measurement beams (26, 28) such that the reference beams (22, 24) travel through a vacuum within the etalon while the measurement beams (26, 28) travel a like distance through the etalon (16) in ambient air. In varying the distance traveled by the laser beams (22, 24, 26, 28) within the etalon (16) any interference fringes detected by an interference fringe detection device (20) are attributable to differences in the optical paths of the measurement beams (26, 28) as compared to that of the reference beams (22, 24) which, in turn, is entirely attributable to the ambient index of refraction. In a first preferred embodiment of the improved refractometer (10) the angular distance between a pair of plates (30, 32) is varied by rotation of the etalon (16).

Abstract: A servo track writing apparatus (10, 210) for writing servo tracks (16) on a media disk (14) of a disk drive assembly (12), the servo track writing apparatus (10, 210) having a laser interferometer (30) for positioning a remote servo track positioning arm (48, 248) with a second cube corner retroreflector (46) attached thereto. A relationship determining apparatus (56, 256) determines the physical relationship between the track positioning arm (48, 248) and a head positioning arm (22) or linear head actuator (220) using a light emitting device (58) and a photosensitive diode array (60).