# US 5,347,358 A · Refractometer

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- Number: US 5,347,358 A
- Document ID: US5347358A
- Status: Granted
- Kind: A
- Application number: 08/094,524
- Filed: 1993-07-20
- Granted: 1994-09-13
- Earliest claimed: 1992-07-20
- Assignees: Carl Zeiss Jena GmbH
- Inventors: Wolfgang Nebe; Rolf Godat
- Web page: https://patentgrep.com/patent/US5347358A

## CPC

- G01N 21/0303: {Optical path conditioning in cuvettes, e.g. windows; adapted optical elements or systems; path modifying or adjustment (G01N21/031 - G01N21/15 take precedence)}
- G01N 21/4133: {Refractometers, e.g. differential}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

The invention relates to a transmitted-light refractometer wherein a slit diaphragm is imaged on a diode array through a cuvette holding the sample. The cuvette itself is arranged in the telecentric beam path. The exit window of the cuvette has several regions in which the inner surfaces of the exit window are inclined differently to the inner surface of the entry window. In this way, several slit images are generated on the diode array and the relative spacings of these images are independent of a possible disadjustment of the condenser and the objective. An embodiment of the invention permits the simultaneous measurement of the refractive index and the absorption of the sample.

## Claims

### Claim 1

A refractometer comprising:
a light source for generating rays of light;
illuminating optic collimating means for collimating said rays to form a collimated light beam defining an optical axis and having a predetermined cross section transverse to said axis;
a cuvette arranged on said axis and defining a hollow enclosed interior space for receiving a sample to be analyzed;
said cuvette having a transparent entry window and a transparent exit window for passing said light beam into and out of said interior space, respectively;
said entry window having an entry inner surface and said exit window having an exit inner surface and said inner surfaces delimiting said interior space;
sensor means disposed downstream of said exit window and defining a plurality of independently registering surface areas for detecting deflections of the light transmitted through said cuvette;
said inner surfaces extending over at least two regions of said cross section of said collimated light beam; and,
said exit inner surface being subdivided into a plurality of component surfaces arranged in corresponding ones of said regions of said cross section with said component surfaces being inclined at different angles with respect to each other.

### Claim 2 (depends on 1)

The refractometer of claim 1, said sensor means being a line sensor.

### Claim 3 (depends on 1)

The refractometer of claim 1, said sensor means being a surface sensor.

### Claim 4 (depends on 1)

The refractometer of claim 1, one of said component surfaces and said entry inner surface being mutually parallel in one of said regions of said cross section.

### Claim 5 (depends on 1)

The refractometer of claim 1, two of said component surfaces being in corresponding ones of said two regions and being arranged at the mutually opposite equal angles with respect to each other.

### Claim 6 (depends on 5)

The refractometer of claim 5, said two regions of said cross section being first and second regions and said cross section having a third region; said two component surfaces of said exit inner surface being first and second component surfaces and said exit inner surface having a third component surface in said third region and said third component surface being parallel to said entry inner surface.

### Claim 7 (depends on 1)

The refractometer of claim 1, said cuvette including means for defining a beam path uninfluenced by the sample.

### Claim 8 (depends on 1)

The refractometer of claim 1, further comprising an objective arranged on said axis and being interposed between said cuvette and said sensor means; said objective defining a focal plane; and, said sensor means being mounted in said focal plane.

### Claim 9 (depends on 1)

The refractometer of claim 1, said collimating means defining a focal plane between said light source and said collimating means; said sensor means being disposed in said focal plane; said exit window having an outer surface facing away from said collimating means; and, said cuvette having reflective means formed on said outer surface of said exit window.

### Claim 10 (depends on 1)

The refractometer of claim 1, one of said windows being exchangeable.

### Claim 11 (depends on 1)

The refractometer of claim 1, further comprising an evaluation and display device connected to said sensor means for providing a simultaneous display of the refractive index and absorption of said sample.

### Claim 12 (depends on 1)

The refractometer of claim 1, said cuvette being a through-flow cuvette.