1. An optometry apparatus comprising:
an eye chart presentation optical system that presents an optometric chart to an eye to be examined; and
a control unit that controls the eye chart presentation optical system to present the optometric chart,
wherein the control unit executes instant presentation of the optometric chart by controlling the eye chart presentation optical system to finish presenting the optometric chart when an instant presentation time has elapsed after the eye chart presentation optical system starts presenting the optometric chart.
2. The apparatus as claimed in claim 1, wherein the control unit executes continuous presentation by controlling the eye chart presentation optical system to present the optometric chart to the eye continuously, and
wherein the control unit selects the instant presentation or the continuous presentation.
3. The apparatus as claimed in claim 1, wherein the instant presentation time is set to prevent a brain from correcting an image representing nerve signals transmitted to the brain.
4. The apparatus as claimed in claim 1, further including an instant presentation starter that starts the instant presentation of the optometric chart by the eye chart presentation optical system.
5. The apparatus as claimed in claim 1, wherein the eye chart presentation optical system presents a presentation position marker to show a position for executing the instant presentation of the optometric chart.
6. The apparatus as claimed in claim 1, further including a reaction unit that is manipulated to input a reaction against the optometric chart presented by the eye chart presentation optical system.
7. The apparatus as claimed in claim 1, further including an instant presentation time setting unit that sets the instant presentation time.
8. The apparatus as claimed in claim 1, wherein the optometric chart is an Amsler grid chart having a latticed pattern.
9. The apparatus as claimed in claim 1, further including a refractive power measurement light projection optical system that projects measurement light onto ocular fundus of the eye; and a refractive power measurement light receiving optical system that receives light reflected by the ocular fundus,
wherein the control unit measures ocular refractive power of the eye based on the received light at the refractive power measurement light receiving optical system, and
wherein the eye chart presentation optical system presents the optometric chart to the eye.
10. The apparatus as claimed in claim 9, further including an ocular characteristics measurement light projection optical system that projects another measurement light onto the eye for measuring ocular characteristics other than the ocular refractive power; and
an ocular characteristics measurement light receiving optical system that receives the another measurement light that is reflected at the eye.
11. A subjective measurement method for measuring ocular characteristics of an eye to be examined of a subject by presenting an optometric chart to the eye and determining how the subject sees the presented optometric chart, the method comprising:
a step for starting presentation of the optometric chart,
a step for determining whether or not an instant presentation time elapses after the presentation starts, and
a step for finishing the presentation of the optometric chart when it is determined that the instant presentation time has elapsed.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A system for perforating a well, comprising:
a perforating gun including one or more perforating charges for firing to perforate the well;
a wireline for suspending the perforating gun in the well, the wireline including an inner sheath with an inner sheath strength and an outer sheath with an outer sheath strength differing from the inner sheath strength;
a swivel for enabling rotation with the perforating gun with respect to a lower end of the wireline; and
a rotational latching mechanism for rotating the perforating gun with the lower end of the wireline in one direction, while rotationally separating the gun from the lower end of the wireline in an opposing direction, such that tension in the wireline results in rotational torque to rotate the gun in the well, and the rotational latching mechanism separates the rotational torque from the gun in the opposing direction.
2. The system as defined in claim 1, further comprising:
an orientation sub suspended in the well with the perforating gun and including a plurality of sensors by determining the azimuthal position of the gun in the well.
3. A system as defined in claim 2, wherein the wireline includes one or more conductors for transmitting signals from the orientation sub to the surface.
4. A system as defined in claim 3, further comprising:
surface equipment responsive to signals from the orientation sub, the surface equipment including a computer and a display.
5. A system as defined in claim 1, wherein the swivel further comprises:
an inner mandrel;
an outer mandrel rotatable relative to the inner mandrel; and
a slip ring assembly for transmitting signals between the inner mandrel and the outer mandrel.
6. A system as defined in claim 5, further comprising:
a pressure compensator for maintaining a desired pressure in an annulus between the inner mandrel and the outer mandrel relative to the environment external of the swivel.
7. A system as defined in claim 1, wherein the rotational latching mechanism includes a ratcheting mechanism.
8. A system as defined in claim 7, wherein the ratcheting mechanism includes a gear and pawl assembly.
9. A system as defined in claim 8, wherein the gear and pawl assembly includes a gear secured to an inner mandrel of the swivel, and a pawl mounted on an outer mandrel of the swivel.
10. A system as defined in claim 9, wherein the gear and pawl assembly includes a biasing member for biasing the pawl toward the gear.
11. A system as defined in claim 7, wherein the swivel includes a swivel sub, and the ratcheting mechanism is housed within the swivel sub.
12. A system for positioning a tool in a well, comprising:
a wireline for suspending the tool in the well, the wireline including an inner sheath with an inner sheath strength and an outer sheath with an outer sheath strength differing from the inner sheath strength;
an orientation sub secured to the tool, the orientation sub including a plurality of sensors by determining the azimuthal position of the tool in the well;
a swivel for enabling rotation with the tool with respect to a lower end of the wireline;
a rotational latching mechanism for rotating the perforating gun with the lower end of the wireline in one direction, while rotationally separating the gun from the lower end of the wireline in an opposing direction, such that tension in the wireline results in rotational torque to rotate the gun in the well, and the rotational latching mechanism separates the rotational torque from the gun in the opposing direction; and
surface equipment responsive to signals from the orientation sub, the surface equipment including a computer and a display.
13. A system as defined in claim 12, wherein the wireline includes one or more conductors for transmitting signals from the orientation sub to the surface.
14. A system as defined in claim 12, wherein the swivel further comprises:
an inner mandrel;
an outer mandrel rotatable relative to the inner mandrel; and
a slip ring assembly for transmitting signals between the inner mandrel and the outer mandrel.
15. A system as defined in claim 12, wherein the rotational latching mechanism includes a ratcheting mechanism.
16. A system as defined in claim 15, wherein the ratcheting mechanism includes a gear and pawl assembly.
17. A method of positioning a tool in a well, comprising:
lowering the tool from a wireline into the well, the wireline including an inner sheath with an inner sheath strength and an outer sheath with an outer sheath strength differing from the inner sheath strength;
providing a swivel for rotating the tool with respect to a lower end of the wireline;
providing a rotational latching mechanism for rotating the tool with a lower end of the wireline in one direction, while rotationally separating the tool from the lower end of the wireline in an opposing direction;
positioning the tool, the swivel, and the rotational latching mechanism at a depth in the well until varying tension in the wireline results in the tool being rotated to a desired azimuthal position; and
thereafter axially moving the tool in the well with the wireline to the desired depth, with the rotational latching mechanism rotationally disconnecting the tool from the wireline as the tool moves in the well to the desired depth.
18. A method as defined in claim 17, further comprising:
providing an orientation sub for determining the azimuthal position of the tool in the well; and
transmitting signals from the orientation sub to the surface through conductors in the wireline.
19. A method as defined in claim 18, further comprising:
confirming the azimuthal position of the tool in the well while at the desired depth.
20. A method as defined in claim 17, wherein providing the swivel comprises:
providing an inner mandrel rotatable relative to an outer mandrel; and
providing a slip ring assembly for transmitting signals between the inner mandrel and the outer mandrel.
21. A method as defined in claim 20, further comprising:
providing a pressure compensator for maintaining a desired pressure differential between fluid and an annulus between an inner and the outer mandrel and the environment exterior of the swivel.
22. A method as defined in claim 17, wherein providing the rotational latching mechanism comprises:
mounting a gear on an inner mandrel of the swivel; and
mounting a pawl on an outer mandrel of the swivel, such that teeth on the gear cooperate with the pawl to rotate the tool in one direction.