JPH0531732B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an apparatus for optically measuring the properties of an object to be measured.

[Prior Art] Conventionally, devices are known that use light to measure the thickness, moisture content, color tone, etc. of an object to be measured. For example, the properties of the object to be measured, such as moisture content, are measured from the ratio of light in a wavelength band that absorbs moisture to light in a wavelength band that does not absorb moisture.

[Problems to be Solved by the Invention] However, if colored substances or other substances are mixed into the object to be measured, the spectral characteristics may be tilted as shown in FIG. For this reason, a method can be considered in which two comparison wavelength bands are provided on both sides of the measurement wavelength and the ratio is calculated using the average of the two components of the comparison wavelength bands.

However, as the number of measurement wavelengths and comparison wavelengths increases, filters and detection elements corresponding to the number of required wavelengths are required, and the number of calculation elements increases, making the device complex and expensive. It was hot.

In view of the above points, it is an object of the present invention to provide an optical measurement device that can simultaneously obtain two components of a comparison wavelength, and that has a simplified measurement system and improved accuracy.

[Means for Solving the Problems] The present invention provides a first signal of a component in the measurement wavelength band of the transmitted light or reflected light from the object to be measured, and a signal of the component of the transmitted light or reflected light from the object to be measured. This is an optical measuring device that measures the properties of an object to be measured from the ratio of a measurement wavelength band to a second signal containing two components in two comparison wavelength bands on both sides.

[Embodiment] FIG. 1 is a configuration explanatory diagram showing an embodiment of the present invention.

In the figure, 1 is a light source for projecting light, the light from this light source 1 is projected onto the object to be measured 3 by a projecting lens 2, and its transmitted light or reflected light is condensed by a condensing lens 4. Through a filter ₅₁ provided in the rotary sector 5 rotated by the motor _{M , which allows the measurement wavelength λ 2 shown} in FIG. and enters the detection element 6. The detection signal of this detection element 6 is amplified by an amplifier 7, and a first signal e ₁ corresponding to a component of the measurement wavelength λ ₂ in the measurement wavelength band and components of both comparison wavelengths λ ₁ and λ ₃ of the comparison wavelength band are generated. A second signal e ₂ containing . . .
Then, the first and second signals of the first and second sample and hold circuits 81 and 82 are divided by the division circuit 10.
By taking the ratio e ₁ /e ₂ of e 1 and e ₂ , a measurement signal e ₀ of the moisture content and other properties of the object to be _measured 3 can be extracted. These sample and hold circuits 81, 8
2. The function of the division circuit 10 may be realized by a calculation means such as a microcomputer or a personal computer including a memory.

That is, the filter 51 as a spectroscopic means of the rotating sector 5 has a transmittance characteristic of a single peak at wavelength λ ₂ as shown in FIG. 3A, and the filter 52 has a transmittance characteristic of a single peak at wavelength It has a double peak transmittance characteristic of λ ₁ and λ ₃ . By using this filter 52, a value corresponding to the sum of _{the components of the comparison wavelengths λ 1 and} λ ₃ on both sides of the measurement wavelength λ ₂ in FIG. 2 can be obtained. The increase cancels out the decrease in the comparison wavelength λ ₃ , making accurate measurement possible at all times.

FIG. 4 is a configuration explanatory diagram showing another embodiment, in which the light from the light source 1 is projected onto the object to be measured 3 through the optical fiber 11, and the reflected light is reflected back into the optical fiber 1.
1, separated by a half mirror 12, and reflected by the half mirror 12, enters the detection element 61 via a filter 51 that transmits the measurement wavelength λ ₂ , and the light transmitted through the half mirror 12 has a comparison wavelength. Filter 52 that transmits both λ ₁ and λ ₃
is incident on the detection element 62 via the detection element 61,
The outputs e ₁ and e ₂ of 62 are ratioed by the measuring means 13, and a measurement signal e ₀ can be taken out.

FIG. 5 shows another embodiment, in which the light from the object to be measured 3 is separated by a spectroscopic mirror 14 as a spectroscopic means, and the spectroscopic mirror 14 transmits light of both wavelengths λ ₁ and λ ₃ . The light that is incident on the detection element 62 and reflected by the spectroscopic mirror 14 is light with wavelengths λ ₁ and λ ₃ excluded, and therefore enters the detection element 61 via the filter 51 that transmits the light with the wavelength λ ₂ . The ratio of the outputs e ₁ and e ₂ of these detection elements 61 and 62 is taken by the measuring means 13, and a measured output e ₀ can be obtained.

FIG. 6 shows another embodiment, in which the light from the light source 1 is
Light is projected onto the object to be measured 3 through a rotating sector 5 having a filter 51 that transmits the measurement wavelength λ ₂ and a filter 52 that transmits the comparison wavelengths λ ₁ and λ ₃ , and the transmitted light or reflected light is detected by the detection element 6 . Detected, the measuring means 13 performs the same ratio calculation as described above, and the properties of the object to be measured 3 are measured.

[Effects of the Invention] As described above, the present invention performs a ratio calculation using a signal containing two comparison wavelengths obtained using a spectroscopic means such as a filter or mirror that allows both comparison wavelengths to pass through. This makes it possible to use a simple device and perform highly accurate optical measurements.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG. 5, and FIG. 6 are explanatory diagrams showing one embodiment of the present invention. 1... Light source, 2... Light projection lens, 3... Target to be measured,
4... Condensing lens, 5... Rotating sector, 51, 52...
Filter, 6, 61, 62...detection element, 7...amplifier, 81, 82...sample hold circuit, 9...synchronous signal generator, 10...divider, 11...optical fiber, 12...half mirror, 13...measuring means , 14
...Spectral mirror.

Claims (1)

[Claims] 1. A first spectroscopic means that transmits light of a component in a measurement wavelength band among transmitted light or reflected light from an object to be measured; a second spectroscopic means that simultaneously transmits both light of two components in two comparison wavelength bands on both sides of the band; means for alternately separating and guiding the signals to the detection element; a first signal corresponding to a component transmitted through the first spectroscopic means and a first signal corresponding to a component transmitted through the second spectroscopic means of the detection signal of the detection element; 1. An optical measuring device comprising: measuring means for measuring the properties of an object to be measured based on the ratio between the two signals. 2. The means for alternately separating and guiding the light to the detection element is characterized in that a rotating sector provided with a first spectroscopic means and a second spectroscopic means, or a mirror for separating light from the object to be measured is used. An optical measuring device according to claim 1.