# US 11,307,058 B2 · Scale and manufacturing method of the same

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- Number: US 11,307,058 B2
- Document ID: US11307058B2
- Status: Granted
- Kind: B2
- Application number: 16/220,368
- Filed: 2018-12-14
- Published: 2019-06-20
- Granted: 2022-04-19
- Earliest claimed: 2017-12-18
- Assignees: Mitutoyo Corporation
- Applicants: Mitutoyo Corporation
- Inventors: Toshihiko Aoki
- Web page: https://patentgrep.com/patent/US11307058B2

## CPC

- G01D 5/34707: {Scales; Discs, e.g. fixation, fabrication, compensation}
- G01D 5/38: by diffraction gratings
- G02B 5/1857: {using exposure or etching means, e.g. holography, photolithography, exposure to electron or ion beams}
- G02B 5/1861: {Reflection gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials (G02B5/1809, G02B5/1828, G02B5/1833, G02B5/1838 and G02B5/1847 take precedence)}
- G02B 7/008: {with means for compensating for changes in temperature or for controlling the temperature; thermal stabilisation}
- G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A scale includes: a substrate that is made of low expansion glass of which a thermal expansion coefficient is 1×10−7/K or less; and scale gratings having a plurality of gratings that are arranged on a first face of the substrate at a predetermined interval and are made of a transparent inorganic material of which a thermal expansion coefficient is more than 1×10−7/K.

## Claims

### Claim 1

A scale comprising:
a substrate that is made of low expansion glass of which a thermal expansion coefficient is 1×10−7/K or less; and
scale gratings having a plurality of gratings that are arranged on a first face of the substrate at a predetermined interval and are made of a transparent inorganic material of which a thermal expansion coefficient is more than 1×10−7/K,
wherein the scale gratings have a structure in which the plurality of gratings are provided on a layer-shaped portion made of the transparent inorganic material, on the first face of the substrate,
wherein the layer-shaped portion is directly provided on the first face of the substrate, and
wherein the layer-shaped portion has a thickness of more than 0.5 μm and 2.5 μm or less.

### Claim 2 (depends on 1)

The scale as claimed in claim 1, wherein a diffraction index of the transparent inorganic material is a diffraction index of the low expansion glass or less.

### Claim 3 (depends on 1)

The scale as claimed in claim 1, wherein the transparent inorganic material is SiO2 or MgF2.

### Claim 4 (depends on 1)

The scale as claimed in claim 1, further comprising:
a stress suppression layer that is provided on a second face of the substrate and suppresses stress of the layer-shaped portion applied to the substrate, the second face facing the first face.

### Claim 5 (depends on 4)

The scale as claimed in claim 4,
wherein the scale gratings are covered by a reflection layer.

### Claim 6 (depends on 5)

The scale as claimed in claim 5,
wherein the reflection layer is a metal layer.

### Claim 7 (depends on 1)

The scale as claimed in claim 1,
wherein the layer-shaped portion has the thickness of 1.0 μm or more and 2.5 μm or less.

### Claim 8 (depends on 1)

The scale as claimed in claim 1,
wherein the substrate is an ultra-low expansion glass-ceramics, and
wherein the scale gratings are SiO2.

### Claim 9 (depends on 1)

The scale as claimed in claim 1, wherein the transparent inorganic material is MgF2.