Mike’s Mirror-Related Conversions

By Mike Lockwood, Feb. 2006

Handy conversions for understanding grit sizes, measurement tolerances, etc.

For simplicity, I assumed one wavelength was 560 nm because that equals an even 22 microinches.

Significance	English	Metric	Wavelengths
One Meter	39.37”	1.00 m	1789500 λ
One Inch	1.000”	0.0254 m	45455 λ
25µ grit	0.001”	25.4 µm	45.4 λ
12µ grit	470 µin	12.0 µm	21.4 λ
9µ grit	354 µin	9.0 µm	16.09 λ
5µ grit	196 µin	5.0 µm	8.94 λ
3µ grit	118 µin	3.0 µm	5.36 λ
Dial indicator resolution	50.0 µin	1.27µm	2.27 λ
1µ grit	39.4 µin	1.00 µm	1.79 λ
1 wavelength	22.0 µin	0.56 µm, 560 nm	1.00 λ
½ wavelength	11.0 µin	0.28 µm, 280 nm	0.50 λ
¼ wavelength	5.5 µin	0.14 µm, 140 nm	0.25 λ
¹/₁₀ wavelength	2.2 µin	0.056 µm, 56 nm	0.10 λ
1 microinch	1.0 µin	0.0254 µm, 25.4 nm	0.046 λ

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