Optical level

Claim 2

An optical level comprising: a. a pool of light-reflective liquid; b. a transparent fluid medium disposed above said lightreflective liquid; c. a solid window disposed over said transparent fluid medium; d. means for containing said light-reflective liquid and said transparent fluid medium sealed under said window; e. the bottom central surface of said window being disposed above the surface of said light-reflective liquid in all operating positions of said level; f. said fluid medium evenly filling the space between said surface of said light-reflective liquid and said bottom central surface of said window in all operating positions of said level; g. the central portion of said window being transparent; h. said fluid medium between said bottom central window surface and said surface of said light-reflecting liquid having suBstantially the same index of refraction as said transparent window portion; and i. the top surface of said window being optically polished.

Claim 3

The level of claim 1 wherein predetermined regions of said top surface of said window are coated to determine the light reflectance of said regions.

Claim 4

The level of claim 2 wherein the periphery of said top surface of said cover has a coating that reflects substantially all incident light.

Claim 5

The level of claim 3 wherein the central portion of said top surface of said window has a coating that partially reflects incident light.

Claim 6

The level of claim 1 wherein said top surface of said window is optically flat.

Claim 7

The level of claim 1 wherein said top surface of said window is formed with a predetermined curvature.

Claim 8

The level of claim 1 wherein said light-reflective liquid comprises mercury.

Claim 9

The level of claim 7 wherein said fluid medium comprises glycerin and water.

Claim 10

The level of claim 7 wherein said fluid medium comprises glycerin and alcohol.

Claim 11

The level of claim 7 wherein said fluid medium comprises an inert oil and a dry, inert gas disposed above said oil with said oil filling the space between said surface of light-reflective liquid and said bottom surface of said window.

Claim 12

The level of claim 7 wherein said mercury contains mineral material.

Claim 13

The level of claim 11 wherein said mineral material colors said surface of said mercury for reflecting light differing in color from incident light.

Claim 14

The level of claim 11 wherein said mineral material comprises material effecting a change in the surface tension of said mercury.

Claim 15

The level of claim 1 wherein said fluid medium is under a pressure less than atmospheric pressure.

Claim 16

The level of claim 1 wherein said top surface of said window and said bottom central surface of said window are substantially parallel.

Claim 17

The level of claim 1 wherein said containing means comprises a shallow, liquid container, said window comprises a cover for said container, and sealing means secures said window to said container.

Claim 18

The level of claim 1 wherein said window comprises an open-bottomed container, and a bottom member is sealed to the bottom of said window to close said container.

Claim 19

The level of claim 1 wherein an under surface of said window surrounding said bottom central surface of said window is disposed above said bottom central surface in all operating positions of said level.

Claim 20

The level of claim 1 wherein said light-reflective liquid comprises mercury, and predetermined regions of said top surface of said window are coated to determine the light-reflectance of said regions.

Claim 21

The level of claim 19 wherein said fluid medium comprises glycerin and water under a pressure less than atmospheric pressure.

Claim 22

The level of claim 20 wherein the periphery of said top surface of said cover has a coating that reflects substantially all incident light, said top surface of said window and said bottom central surface of said window are substantially parallel, and an under surface of said window surrounding said bottom central surface of said window is disposed above said bottom central surface in all operating positions of said level.

Claim 23

The level of claim 21 wherein said mercury contains mineral material that colors the surface of said mercury for reflecting light different in color from incident light, said window comprises an open-bottomed container, and a bottom member is sealed to the bottom of said window to close said container.

Claim 24

An optical leveling method comprising: a. arranging a windowed container of a pool of light-reflective liquid with the window facing upward in position for levelling; b. providing a light-reflective coating on the windowed top surface of said container; c. directing light downward from a source onto said windowed container so that a portion of the light is reflected from said top surface and another portion is reflected through the window from the surface oF said light-reflective liquid; d. optically multiplying any angular difference between the portion of said light reflected from the top surface of said container and the portion of said light reflected from the surface of said light-reflective liquid by a value substantially greater than 1; e. comparing the portion of the light reflected from the top surface of said container with the portion of said light reflected from the surface of said light-reflective liquid in said container to determine any angular difference therebetween; and f. making a mechanical adjustment based on the results of said comparison.

Claim 25

An optical leveling method comprising: a. arranging a windowed container of a pool of light-reflective liquid with the window facing upward in position for levelling; b. providing a light-reflective coating on the windowed top surface of said container; c. directing light downward from a source onto said windowed container so that a portion of the light is reflected from said top surface and another portion is reflected through the window from the surface oF said light-reflective liquid; d. optically multiplying any angular difference between the portion of said light reflected from the top surface of said container and the portion of said light reflected from the surface of said light-reflective liquid by a value substantially greater than 1; e. comparing the portion of the light reflected from the top surface of said container with the portion of said light reflected from the surface of said light-reflective liquid in said container to determine any angular difference therebetween; and f. making a mechanical adjustment based on the results of said comparison.

Claim 26

The method of claim 23 wherein said adjustment is made to bring said top window surface parallel with said liquid surface.

Claim 27

The method of claim 23 wherein said adjustment is made to bring said source closer to a position vertically above said level.

Claim 28

The method of claim 23 including using a light-refractive medium between said top window surface and said reflective surface to amplify any deviation angle between said light reflected from said window and said light reflected from said liquid.

Claim 29

The method of claim 23 wherein said comparison comprises observing interference fringes between said light reflected from said window and said light reflected from said liquid.

Claim 30

The method of claim 23 wherein said adjustment comprises moving a structure supporting said container.

Claim 31

The level of claim 1 wherein said transparent fluid medium is hydroscopic.