Abstract: An apparatus, multi-layer semiconductor substrate and system for testing a high-speed signal through a printed circuit board is provided. Embodiment of the present invention provides an apparatus comprises a multi-layer substrate, one or more transmission lines disposed within the multi-layer substrate, one or more connectors attached to the multi-layer substrate for connecting one or more test cards, a lid, comprising one or more cutouts for the one or more connectors, a clamp for compressing the multi-layer substrate against the lid, and one or more high-speed connectors attached to the one or more test cards, respectively.

Abstract: A strain gage system for an electric motor actuator is provided. The strain gage system may be coupled to or integrally formed in a housing of the electric motor actuator. In various embodiments, the strain gauge system may comprise one or more principle strain gages. In various embodiments, the strain gage system may comprise one or more transverse strain gages.

Abstract: A load detection device for a vehicle seat includes a strain generating body including a first end hole, a second end hole and a strain gauge, a first fixing member including a first middle shaft portion and a first end shaft portion, a second fixing member including a second middle shaft portion and a second end shaft portion, a bracket member including first and second fixing portions connected to each other with a connecting portion, first and second fixing holes, the first end shaft portion is press-fitted into the first fixing hole, the second fixing hole is fitted onto the second end shaft portion in a manner that the second fixing hole includes a degree of freedom of a movement thereof in a lengthwise direction and a movement thereof in a direction intersecting with the lengthwise direction is restricted, and a connecting member.

Abstract: A mount assembly for compression testing of an article of apparel on a compression testing machine. The machine has a head and a sensor. The mount assembly includes a substantially rigid core member and a resilient member that is supported on and that at least partially covers the cover member. The resilient member is configured to support the article of apparel thereon. The resilient member is configured to resiliently deform in response to a compression applied to the article of apparel from the head of the impact testing machine. As such, the sensor detects an effect of the compression on at least one of the resilient member and the core member.

Abstract: An apparatus for load testing a coupon may include a test frame and a pair of spaced apart load balancing assemblies connected to the test frame, each load balancing assembly of the pair of load balancing assemblies including a load leveling mechanism connected to the test frame and a plurality of spaced apart load plates, each load plate of the plurality of load plates having a first end pivotably connected to the load leveling mechanism and a second end, the second end of each load plate including a friction holder configured to frictionally engage an end of the coupon, wherein at least one load balancing assembly of the pair of load balancing assemblies is movable along an axis of movement with respect to an opposed load balancing assembly to communicate a load to the coupon.

Abstract: A testing apparatus and method of extending the life of a testing apparatus may comprise a chassis including a case having a testing module receptacle receiving a plurality of testing modules comprising at least one processor module and a plurality of test modules, each having the same physical footprint, including respective racking mechanisms and inter-module interface connectors; and a backplane with connectors connecting with a respective inter-module connector, and bus-work interconnecting the respective modules through the inter-module interface connectors and the backplane connectors. The backplane may comprise a battery and display connector. The chassis may comprise a display mounting receptacle configured to receive a display unit having a display connector configured to interface with the backplane display connector. A battery receptacle may receive a battery unit, such as a rechargeable battery.

Abstract: The invention relates mainly to a test bench (10) for a radial bearing (14) suitable for being interposed between two members (12, 16) that are movable relative to each other in rotation, the test bench being characterized in that it comprises a radial force measurement device (18) for measuring radial forces exerted on said bearing (14), a radial acceleration measurement device (20) for measuring radial accelerations to which said bearing (14) is subjected, and an electronic calculation unit (26) in communication with the radial force measurement device (18) and with the radial acceleration measurement device (20). The invention also relates to a method of establishing a behavior relationship for the radial bearing (14).

Abstract: A sensor detects relative mechanical movement between two components. The sensor has two arms, and is to be mounted on one of the two components. Each of the arms has pins received in an opening in two fuse portions. The arms are pivotal within a fuse bracket. The two fuse portions include a thin portion to allow each to fracture. The fuse portions are designed to be distinct such that a distinct amount of relative movement between the first and second arms is allowed before each of the fuse portions fracture.

Abstract: A mount assembly for compression testing of an article of apparel on a compression testing machine. The machine has a head and a sensor. The mount assembly includes a substantially rigid core member and a resilient member that is supported on and that at least partially covers the cover member. The resilient member is configured to support the article of apparel thereon. The resilient member is configured to resiliently deform in response to a compression applied to the article of apparel from the head of the impact testing machine. As such, the sensor detects an effect of the compression on at least one of the resilient member and the core member.

Abstract: A housing part for a strain sensor is described. The strain sensor includes at least one sensor element. The housing part includes an interior space for receiving the sensor element. The housing part includes a contract layer of electrically conducting material produced by way of thick film technology, the contact layer being intended for realization of an electrical feedthrough from the interior space to the outside.

Abstract: A load detection device for a vehicle seat includes a strain generating body including a first end hole, a second end hole and a strain gauge, a first fixing member including a first middle shaft portion and a first end shaft portion, a second fixing member including a second middle shaft portion and a second end shaft portion, a bracket member including first and second fixing portions connected to each other with a connecting portion, first and second fixing holes, the first end shaft portion is press-fitted into the first fixing hole, the second fixing hole is fitted onto the second end shaft portion in a manner that the second fixing hole includes a degree of freedom of a movement thereof in a lengthwise direction and a movement thereof in a direction intersecting with the lengthwise direction is restricted, and a connecting member.

Abstract: A technique facilitates drilling of boreholes by enabling improved measurement of strain during drilling applications. A strain gauge is mounted on a drilling component of a drill string. The strain gauge is covered with a volume of liquid, and the liquid is enclosed at least in part with a flexible layer of material. The flexible layer of material is sufficiently flexible to provide a negligible pressure differential between the volume of liquid and the surrounding environment while drilling, thus enabling accurate functioning of the strain gauge.

Abstract: A spring force component tester for determining a load distribution on each end of a spring of generally cylindrical shape using three, mutually-parallel load cells. One tester includes a lower plate and an upper plate movable with respect to the lower plate. Each plate includes a plurality of recesses and a load cell positioned in each recess. Each plurality of recesses is positioned such that a center of each recess is a point on a circle coaxial to the plate. The tester also includes a data logger that obtains and stores load cell outputs from the load cells and spring tester electronics that obtain height measurements of the upper plate and send a trigger signal to a computer. The computer executes application software when the computer receives the trigger signal that reads the load cell outputs stored in the data logger, and calculates a spring force acting along the spring axis between approximately 0.5 Newton and 100 Newton.

Abstract: A test station for testing golf clubs has a clamp on the lower portion holding a shaft extending along a first axis. Sensors along that axis detect shaft vibrations torsion vibrations. Four towers are movably connected to a rail extending along the top portion of the base. Two of the towers have a first vertically adjustable shaft positioner and a device to detect forces exerted on the first shaft positioners. The other two towers also have vertically adjustable shaft positioners. The towers are used to determine stiffness, center of gravity, swing point and other properties. A drawer in the base contains a scale to measure the club length, and a pivoted stop to measure head angle.

Abstract: An instrument housing comprising a first portion having a wedge form, a third portion having a wedge form, a second portion between the first portion and the third portion, a first hinge portion between the first portion and the second portion, the first hinge portion extending normal to a major axis A-A, a second hinge portion between the second portion and the third portion, the second hinge portion extending normal to a major axis A-A, and the second portion having a portion for receiving an instrument.

Abstract: A sensor assembly for sensing relative movement between adjacent panels includes a base and first and second arms pivotally mounted to the base. An electrical connecting element is attached to the first and second arms and holds the first and second arms in a first position to indicate a first condition. When the first and second arms have moved relative to each other by a predetermined amount, the electrical connecting element breaks to indicate a second condition.

Abstract: A system includes a structure and a component. The component including an energy providing device and a protective cover. The structure has a structure surface. The protective cover has a protective cover attachment surface mounted on the structure surface. The energy providing device is located within the protective cover. The protective cover has a protective cover outer surface. The protective cover outer surface is oriented to face a first direction from which an impact load may strike the protective cover outer surface and shear the protective cover from the structure surface. The protective cover outer surface has an outer surface shape facing the first direction. At least a portion of an impact load striking any region of the protective cover outer surface facing the first direction is transferred by the outer surface shape into a compression load.

Abstract: A bandage type sensor arrangement wherein the sensor includes two parts movable with respect to each other, a carrier assembly is connected to the sensor parts for maintaining the sensor parts in place prior to use, and that is readily detachable for releasing the sensor parts while providing a connection of the sensor parts to a surface to be monitored. A cover is included as part of the carrier assembly to protect the operation of the sensor.

Abstract: The present invention relates to a device and system from doing mechanical and electrical measurements and manipulation on nano or micro sized objects using a sample holder adapted to fit in situ of a transmission electron microscope. The sample holder comprise at least two arms each with at least one connector whereby the sample (206) may be mounted between the two connectors forming a bridge closing a gap between the two arms of the sample holder. The sample holder is arranged to provide mechanical forces to a sample mounted on the sample holder and measuring and/or applying electrical signals from the sample while at the same imaging using the transmission electron microscope. Each arm of the sample holder may comprise three substantially parallel beams for electro-thermal actuation.

Abstract: A bracket for mounting a sensor. The bracket may include a base with a base loading mechanism for mating with the sensor, a first arm attached to the base, and a second arm adjustably attached to the base. The first arm may include a first arm loading mechanism for mating with the sensor.

Abstract: A bandage type sensor arrangement wherein the sensor includes two parts movable with respect to each other, a carrier assembly is connected to the sensor parts for maintaining the sensor parts in place prior to use, and that is readily detachable for releasing the sensor parts while providing a connection of the sensor parts to a surface to be monitored. A cover is included as part of the carrier assembly to protect the operation of the sensor.

Abstract: The apparatus has an elongate and vertically running carrier (90) for pressure sensors (50), which precedes a group of levers (71 ). The cross section of this carrier (90) is arcuate, so that it has two flanks (93, 94 ). During the testing of a leg garment (80), this carrier (90) simulates the region of the shin. The apparatus has, furthermore, moldings or stays (88) which are carried by the levers and which simulate the rear face of the calf or of the thigh of a leg. The width of these stays corresponds to the width of the calf or of the thigh of a leg. The apparatus also comprises two longitudinally running groups (50) of pressure sensors, one of which is in each case assigned to outside of one of the flanks (93, 94) of the carrier (90). The leg garment (80) to be tested, in order to test it, is slipped over this apparatus in such a way that it lies on the outer faces both of the carrier (90) and of the stays and exerts pressure on the pressure sensors (51).

Abstract: A method and apparatus for inspecting the walls of an underground pipe from inside the pipe in which an inspection apparatus having a circular planar platform having a plurality of lever arms having one end pivotably attached to one side of the platform, having a pipe inspection device connected to an opposite end, and having a system for pivoting the lever arms is inserted into the underground pipe, with the inspection apparatus oriented with the planar platform disposed perpendicular to the pipe axis. The plurality of lever arms are pivoted toward the inside wall of the pipe, contacting the inside wall with each inspection device as the apparatus is conveyed along a length of the underground pipe.

Abstract: Disclosed herein is a sensing device mounting mechanism allowing for a sensing device to be mounted in relation to a supporting structure. The sensing device mounting mechanism comprises a housing portion having a snapping mechanism. The snapping mechanism allows the housing portion to be coupled to at least one of the supporting structure, the sensing device, and an additional portion of the sensing device mounting mechanism.

Abstract: A mounting device for supporting a sensing device in relation to a supporting structure, and related method of installing a sensing device, are disclosed. In at least some embodiments, the mounting device includes a first housing portion having a first appendage, and a second housing portion having a second appendage, where the second housing portion is slidable in relation to the first housing portion. The mounting device further includes an actuating portion capable of causing sliding movement between the housing portions, where the sensing device is supported within at least one of the housing portions. In some embodiments, a rotatable swivel ball on which the sensing device is supported is contained within at least one of the housing portions, and actuation of the actuating portion results in both the coupling of the mounting device to a supporting structure and a setting of a position of the swivel ball.

Abstract: A subject having a test surface is held by a holder so that an axis line of the test surface intersects the direction of gravity and applied with a load, from above and beneath, that is optimized for accurate measurement of surface profile of the test surface. For optimization of the load, the test surface is applied with variable exploratory load strong enough to cause bending deformation in the test surface and a linear-functional relationship existing between more than two different exploratory loads and sizes of surface deformation caused with the different exploratory loads is derived. With the aid of linear-functional relationship, a load that induces the subject to cause surface deformation less than a predetermined size of surface deformation admissible, for example, as a manufacturing en-or is used as an optimized load.

Abstract: In a torsion angle measuring method and device for a magnetic-disk suspension, a datum surface of the suspension is fixed to a fixture under pressure, the fixture being provided with a smooth criterion surface having known torsion angles set for the suspension datum surface. A roll angle and a pitch angle of a slider loading surface of the suspension to the datum surface when the suspension is fixed to the fixture are measured.

Abstract: A multipurpose utility mounting assembly for a handheld field maintenance tool is disclosed. The assembly includes a number of features that allow effective use of the handheld field maintenance tool for a wide variety of mounting techniques that may be encountered in the field. Specifically, the mounting assembly includes features that facilitate handheld use, benchtop use and temporary hanging use. In some embodiments, the multipurpose utility mounting assembly is detachably mountable to a handheld field maintenance tool.

Abstract: A block test stand includes a body having a base and two rods each having a first end secured on the base and a second end having a barrel laterally secured on the two rods. A bearing member is partially slidably received in the barrel. The bearing member includes a piston cap slidably received in the barrel, and a piston is received in the piston cap and extends through the barrel. A connector is secured on a distal end of the piston. A bearing seat is connected to the connector. The bearing seat includes a block and a spheroid secured on the block. The spheroid is partially universally received in the socket in the connector and a concentric ring is sleeved on the connector and secured on the block to hold the block in place.

Abstract: The present invention relates to a miniature rheometer, a parallel rheometer, and improved force sensor elements which may advantageously be used in combination with the miniature rheometer and the parallel rheometer. The miniature rheometer is adapted to determine rheological characteristics of materials which are provided in the form of small quantity samples. The miniature rheometer comprises an actuating element, a sensing element and a feedback circuit to provide rebalance of the shear force applied by the sample to the sensing element, which insures an exceptional stiffness in determining the shear strain so as to allow measurements of high accuracy. The parallel rheometer of the present invention allows simultaneous measurements of a plurality of samples so as to allow of a plurality of samples within a short time period. The force sensor element according to the present invention allows simultaneous measurement of a shear force and a normal force applied to the sensor element.

Abstract: An apparatus for accurately locating a micro-electronic chip in a chip-holding cavity for visual testing, the chip having at least a front wall and a pair of opposed, spaced-apart side walls, wherein the front wall meets with each of the side walls to form opposed, spaced-apart first and second front edges, comprising a cavity side wall formed to juxtapositionally abut at least one of the side walls of the chip, the cavity side wall having formed therein a depression creating a shadow projecting forward from the depression, wherein the first front edge of the chip forms a border of the shadow to form an objectively measurable contrast in grayness between the shadow and the chip.

Abstract: “ELECTRIC METER BOX HEAT SHIELD” This simple new way to protect and improve the preformance, extend the usful life of an existing electrical meter box. Consumers can install with out any electrical training. It gives consumers a wepon to help fight high electric costs and costly repairs when installed on a meter box that is in normal operating condition. simply slip the shield oved the meter glass to provide shade on the enclosure there by reducing tempture of the enclosure.

Abstract: The invention is concerned with a compression stress sensor having a proof body (1) and strain gauges (7) connected together to form a Wheatstone bridge. The proof body (1) is made as a single piece from a monolithic rod which is cylindrical or prismatic with a circular or a regularly polygonal transverse section. This rod (1) is traversed in its median part by at least one pair of passages (3, 4) orthogonal one with respect to the other and located in a plane perpendicular to the longitudinal axis (X) of the proof body (1) to define between them independent measure columns (5). The end faces (2, 2a) of the proof body provide bearing faces receiving the forces to be measured and a strain gauge (7) is fixed to a surface of each independent measure column (5).

Abstract: A connection device and test system is capable of stable, low load damage-free probing of devices under test, which have many pins with a narrow pitch. Furthermore in order to achieve high speed exchange of electrical signals or so-called high frequency electrical signals, a support member is provided for supporting the connection device, a plurality of pointed contact terminals are arrayed in an area on the probing side, a multilayer film is provided having a plurality of lead out wires electrically connected to the contact terminals and a ground layer enclosing an insulation layer, and a frame is clamped on the rear side of the multilayer film.

Abstract: A redundant linkage and sensor assembly which includes a sensor that enables indication of the magnitude and direction of forces applied to the linkage, while maintaining full mechanical strength and function of the linkage. The linkage includes an inner first tube and an outer second tube arranged to move in telescoping fashion, a spring being connected between the outer tube and the inner tube. Within the outer tube the inner tube is connected to a stop assembly also connected to the outer tube, which stop assembly limits movement of the inner tube with respect to the outer tube to a selected range. A position sensor is also connected between the two tubes within the second tube to provide a signal indicative of relative movement. Whereby the axial forces on the linkage are monitored as the signal from the position sensor is related to movement in a known way and movement is related to applied force through the spring in a known way.

Abstract: A device for detecting and warning of floodwater about a building structure, the device including a plurality of selectable remote alarm indicators, a matching plurality of alarm selector switches for selectively enabling and disabling the remote alarm indicators, means for detecting the presence of water, a power circuit with backup battery capability, a selectable intermittent alarm signal generator, a master remote alarm enabler switch, an automatic audio alarm indicator which emits different alarm noises depending on a floodwater condition and/or a low power condition, an alarm priority override circuit, a power status light indicator, and a selectively activatable self-test circuit for simulating a floodwater condition.

Abstract: A clamp for securing apparatus such as end-of-train equipment to a railroad coupler head includes a first finger member that is mounted to pivot about a pivot pin in scissors-like manner between a fixed second and third finger member affixed to a housing, a threaded rod and cooperating piston for pivoting the first finger member away from the fixed second and third finger members, a rail member for abutting against an outside surface of the coupler head, and a crank and handle for tightening the grip of the first, second and third fingers on the inner surfaces of the core hole when the crank is rotated.

Abstract: The measuring platform according to the invention, for recessing into road surfaces, consists of a base plate and cover plate supported in cross section on two supporting points fitted with piezoelectric shear crystals, enabling the shear force of an overrunning wheel to be measured. If the supporting points are equipped with piezoelectric pressure crystals, it is possible to measure the axle load with the same platform arrangement. This offers new possibilities, especially on or after gradients, for verifying the functional efficiency of braking and ABS systems and taking out of service vehicles with defective braking equipment.

Abstract: A test apparatus is formed of an error area computing device, an upper limit value computing portion and a delay time computing portion. The error area computing device computes an error area corresponding to a difference between waves of a request signal and an output signal to thereby correct control constants for a PID controller based on the error area. The upper limit value computing portion prevents the control constants from being corrected at values higher than upper limit values, and the delay time computing portion computes a phase delay time between the request signal and the output signal. In case the request signal has a higher frequency, the error area is computed as a value from which an error area due to the phase delay time is deducted. Thus, in the test apparatus, the control constants of the PID controller can be optimized for every cycle of an input signal, i.e. the request signal, and in the process of optimizing of the control constants, a bad influence is not exerted to a specimen.

Abstract: A measuring device is provided for measuring one or more properties, such as thickness and tension profiles of a thin object, especially a fabric. The measuring device includes an upper mobile member adapted to be placed on the top side of the thin object, a lower mobile member adapted to be placed on the bottom side of the thin object, directly below the upper mobile means, magnets for holding together the upper and the lower mobile members with the thin object in between without damaging the thin object, and a measuring device provided on at least one of the mobile members for measuring the properties of the thin object. The mobile members are moveable together or separately across the surface of the thin object.

Abstract: In a measuring arrangement comprising a strain gage section (10) constructed of at least one SG (strain gage) (15), and integrated in a measurement pickup (1), an additional circuit (20) amplifies modulated output signals of the SG section (10), and is also integrated in the measurement pickup (1). The measuring arrangement thus obtained is used for general measuring tasks, particularly for commercially available domestic or industrial scales including weighing devices operated by means of commercially available batteries. As an additional circuit, a modulation amplifier can be used which consists of a modulator constructed as squarewave generator, an alternating-voltage amplifier and a demodulator, the demodulator being a bridge rectifier composed of four electronic (on/off) switches or two electrical changeover switches.

Abstract: A mechanical test system is provided comprising a primary actuator arranged so as to create mechanical movement of a first specimen holder along an axis of actuation and an oppositely oriented secondary actuator arranged so as to create mechanical movement of a second specimen holder along the axis of actuation. The magnetostrictive actuator comprises a magnetostrictive assembly including a magnetostrictive element and a flexible disk mechanically coupled to the magnetostrictive element. The magnetostrictive element comprises either a magnetostrictive material portion with a plurality of cooling fluid bores formed within the magnetostrictive material portion or an epoxy matrix with a plurality of cooling fluid bores and a plurality of magnetostrictive rods formed within the epoxy matrix.

Abstract: A vehicle load measuring device includes a sensing element for detecting a strain to measure the load of a vehicle, in which the sensing element is formed in a pin shape, and a device for supporting a suspension of the vehicle, in which a hole is formed in the supporting device and the sensing element is fitted into the hole, wherein the load of the vehicle is measured based on the strain detected by the sensing element produced in response to the load supported by the supporting device, and a positioning groove being formed on a surface of the device for supporting a suspension, wherein when the device for supporting a suspension connects a suspension with a bracket on the vehicle the device for supporting a suspension is positioned by use of the positioning groove, thereby determining the direction of the load to be applied to the sensing element and preventing the device for supporting a suspension from moving in a predetermined direction with respect to the bracket.

Abstract: A warp tension measuring apparatus for weaving machines or looms has a force sensor or pick-up (3) and a member (2) which is in active communication with the force sensor (3) to transfer a force acting on the members (2) onto the force sensor. The force sensor (3) is provided with a resilient element (9) to improve the introduction of force, on the one hand, and to damp mechanical oscillations, on the other hand.

Abstract: A strain gage apparatus that includes a unique mounting mechanism which enables the apparatus to be directly mounted on a load-bearing structure without having to modify the structure thereby making the apparatus particularly useful for measuring the weight of articles and materials disposed within various types of structures as, for example, tanks and hoppers.

Abstract: A force sensor is disclosed in which strain is measured exclusively by shear strain gages mounted on L or T-shaped legs. Each such leg has at least two arms which are orthogonal to one another. That is, the arms of the L or T each have a lengthwise or longitudinal axis, and two of these longitudinal axes are oriented at approximately 90.degree. with respect to one another. Each leg also has at least two shear strain gages mounted on orthogonal arms to measure forces in orthogonal directions. Three or more of these L or T shaped legs are integrated in a generally cylindrical and hollow body defining the force sensor. The shear strain gage outputs from the arms of this structure are sent to a digital signal processor which determines the magnitude and direction of any force/moment applied to the cylindrical body. Further, the shear strain gages are mounted in pockets sized to hold the strain gages and provide increased sensitivity to shear strain.

Abstract: A clamp-on structural strain-gage sensor that is mounted to dynamic load-bearing structures, such as sucker-rod type oil well pumps, to produce an electrical output proportional to the deflection of such structures. The apparatus uniquely includes an active electronic temperature correcting circuit to provide compensation for the erratic effects caused by uneven thermal heating of the load-bearing structure.

Abstract: A load cell includes a load sensing section which is formed by a rigid load introduction section, a rigid load support section and a strain sensing section, and a base plate having a neck and two parallel plate-shaped rigid sections. One part of the plate-shaped rigid section of the base plate is integratedly fixed to the load sensing section, and the strain gauges are mounted on the strain sensing section formed on the load sensing section so as to detect a load applied to the load introduction section and convert the magnitude of a measured load into a quantity of electricity.

Abstract: By the fastening device, two electric transmitters are to be arranged on a supporting structural part from which two extensions (11) protrude spaced from each other. For this purpose, one bored attachment end (15, 16) each of the two transmitters are arranged each on one side (13, 14) of one of the two extensions (11) on a threaded bolt (1, 2). The threaded bolt is screwed, with one collar (5, 6) each lying on both sides against the extension (11), directly to the latter. The attachment ends each have such a large recess (20 22) that they rest only on the extension without resting on the collars (5, 6). The threaded bolt (1, 2) is provided on the outside on both ends with a threaded section (9, 10). Nuts (25, 26) which are screwed on the respective threaded sections press in each case one of the two attachment ends (15, 16) against the extension (11).

Abstract: The principal surfaces of an oscillator quartz crystal body for a temperature sensor oscillator are plane, parallel and of substantially the same size and are oriented with respect to the usual x-y-z coordinate system of electric, mechanical and optic axes so that the angle .phi. of the electric (x) axis with respect to either of these planes lies within a tolerance range extending from +1.degree. to -1.degree., while the angle .theta. of the optic (z) axis with respect to either of these plane lies either in the 3.degree.-6.degree. range or in the 68.degree.-72.degree. range. Since in the regions of .theta.=4.degree. and .theta.=70.degree. the change of the temperature coefficient with variation of the angle .theta.