1. A distance-change detecting method for detecting a change of the distance between a second optical means and an optical recording medium in an optical system having a first optical means for condensing the light to irradiate the optical recording medium and the second optical means being set between the first optical means and the optical recording medium in order to realize a numerical aperture larger than that of the first optical means, the method comprising the steps of:
detecting the light incident to the second optical means from the first optical means at an incidence angle at which a numerical aperture is larger than a predetermined value and reflected from a plane facing the optical recording medium out of the second optical means;
detecting the distance change in accordance with the amount of the reflected light;
calculating a light amount ratio between a high frequency component of the incident light and a high frequency component of the reflected light; and
controlling a distance between the optical recording medium and the second optical means so that the distance between the disk and the second optical means is constant in a near-field range,
wherein one of the light incoming to the first optical means and the light incoming to the second optical means is detected, and
wherein the distance is controlled based on the calculated ratio.
2. The distance-change detecting method according to claim 1, wherein
the second optical means is a solid immersion lens, and the light incoming to the second optical means from the first optical means at an incidence angle at which a numerical aperture is larger than 1 and reflected from a plane of the second optical means facing the optical recording medium is detected.
3. A distance-change detector for detecting a change of the distance between a second optical means and an optical recording medium in an optical system having a first optical means for condensing the light to irradiate the optical recording medium and the second optical means set between the first optical means and the optical recording medium in order to realize a numerical aperture larger than that of the first optical means, the detector comprising:
a light detection means for detecting the light incoming to the second optical means from the first optical means at an incidence angle at which a numerical aperture is larger than a predetermined value and reflected from a plane of the second optical means facing the optical recording medium;
a first detection means for controlling the distance between the optical recording medium and the second optical means so that the-distance between the optical recording medium and the second optical means is constant in a near-field range; and
a second light-detection means for detecting one of the light incoming to the first optical means and the light incoming to the second optical means,
wherein the detection means is comprised of comparison means for calculating a ratio between a high frequency component of the incident light and a high frequency component of the reflected light.
4. The distance-change detector according to claim 3, wherein
the second optical means is a solid immersion lens, and
the light detection means detects the light incoming to the second optical means from the first optical means at an incidence angle at which a numerical aperture is larger than 1 and reflected from a plane of the second optical means facing the optical recording medium.
5. The distance-change detector according to claim 4, wherein
a member for controlling reflection of light is formed on at least one of a plane of the second optical means facing the optical recording medium and a portion of the optical recording medium closer to the second optical means than a signal recording plane of the optical recording medium.
6. The distance-change detector according to claim 3, wherein
a member for controlling reflection of light is formed on at least one of a plane of the second optical means facing the optical recording medium and a portion of the optical recording medium closer to the second optical means than a signal recording plane of the optical recording medium.
7. The distance-change detector according to claims 3, wherein
a member for controlling reflection of light is formed on at least one of a plane of the second optical means facing the optical recording medium and a portion of the optical recording medium closer to the second optical means than a signal recording plane of the optical recording medium.
8. A focus control method for controlling the distance between a second optical means and a optical recording medium in an optical system having a first optical means for condensing the light to irradiate the optical recording medium and a second optical means set between the first optical means and the optical recording medium in order to realize a numerical aperture larger than that of the first optical means, the method comprising the steps of:
detecting the light incident to the second optical means from the first optical means at an incidence angle at which a numerical aperture is larger than a predetermined value and reflected from a plane out of the second optical means facing the optical recording medium;
calculating a light amount ratio between a high frequency component of the incident light and a high frequency component of the reflected light; and
controlling a distance between the optical recording medium and the second optical means so that the distance between the optical recording medium and the second optical means is constant in a near-field range,
wherein the distance is controlled based on the calculated light amount ratio.
9. The focus control method for controlling the focus of a convergent lens according to claim 8, further comprising the steps of:
floating the convergent lens above the face of an irradiated object by positive-pressure air; and
attracting the convergent lens to the irradiated object by negative-pressure air.
10. The focus control method according to claim 9, wherein
the distance between the convergent lens and the irradiated object is controlled by controlling the air pressures.
11. The focus control method according to claim 9 or 10, wherein
a focal position is corrected by driving the convergent lens with an electrical driving means.
12. A focus controller for controlling the distance between a second optical means and an optical recording medium in an optical system having a first optical means for condensing the light to irradiate the optical recording medium and the second optical means set between the first optical means and the optical recording medium in order to realize a numerical aperture larger than that of the first optical means, the controller comprising:
a light detection means for detecting light incident to the second optical means from the first optical means at an incidence angle at which. a numerical aperture is larger than a predetermined value and reflected from a plane of the second optical means facing the optical recording medium;
a detection means for calculating a light amount ratio between a high frequency component of the incident light and a high frequency component of the reflected light and detecting a distance change in accordance with the calculated ratio; and
a control means for controlling the distance between the optical recording medium and the second optical means based on the calculated ratio so that the distance between the optical recording medium and the second optical means is constant in a near-field range.
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. Device for connecting pipe parts between two compartments of a filtration unit for water of a swimming pool, the filtration unit comprising a filtration compartment submerged in the water and equipped with at least one filtration means and a pumping compartment situated outside of the swimming pool and equipped with at least one suction and return pump, the compartments being connected by a common connecting part that straddles walls of the swimming pool, the at least one filtration means and at least one pump being connected in combination with suction pipe parts and return pipe parts, the suction pipe parts and the return pipe parts each comprising one conduit part situated in the filtration compartment and one conduit part situated in the pumping compartment, and further comprising, at the common connecting part, a watertight connecting module between the suction pipe parts and between the return pipe parts, a thickness of the connecting module being less than a diameter of the suction and return pipe parts.
2. Device according to claim 1, wherein the module has a thin flat cross section and defines, in section, two separate internal conduits, each conduit having members for watertight connection with flat-section connectors, the connectors being fixed to the conduit parts of the suction and return pipes positioned in the filtration and pumping compartments, and the module being arranged between the two compartments, at the common connecting part.
3. Device according to claim 2, wherein the connecting members of the module comprise flat-section adaptors in communication with the conduits.
4. Device according to claim 2, wherein the flat-section connectors are made integral, directly or by being connected, with round-section adaptors able to be connected by watertight engagement with the pipe parts.
5. Device according to claim 2, wherein the module comprises an independent add-on element fixed in a watertight manner to the common connecting part, between the two compartments.
6. Device according to claim 5, wherein the module has in section a profile able to fit in a complementary profile serving as a bearing cradle formed in a thickness of a separating plate belonging to the common connecting part.
7. Device according to claim 2, wherein the module and the two compartments are connected together by a common linking frame fitted with covers for closing each of said compartments.
8. Device according to claim 2, wherein the adaptors have a rectangular cross section.