Spectrophotometric colorimeter based on LED light source and method for realizing the same

Patent metadata

Field	Value
Publication number	US-9243953-B1
Application number	US-201514618036-A
Country	US
Kind code	B1
Filing date	Feb 10, 2015
Priority date	Dec 16, 2014
Publication date	Jan 26, 2016
Grant date	Jan 26, 2016

Abstract

The present disclosure provides a spectrophotometric colorimeter based on LED light source, wherein the spectrophotometric colorimeter includes an integrating sphere, a coupling light path, and a spectrometer. An inner wall of the integrating sphere is arranged with a composite light source consisting of eight LEDs; a sphere wall of the integrating sphere defines an incident aperture; light emitted from each LED enters an interior of the integrating sphere through the incident aperture and is irradiated onto the inner wall. The coupling light path is configured to couple light at a measurement caliber such that the light can enter an incident split and to eliminate stray light from the inner wall. After emitting out from an observation aperture of the integrating sphere, the light enters the incident split through the coupling light path and is irradiated onto a linear-array sensor after being split by a spectral light path; and different pixels of the linear-array sensor correspond to light radiation strengths at different wavelengths.

First claim

What is claimed is:

1. A spectrophotometric colorimeter based on LED light source, wherein the spectrophotometric colorimeter comprises an integrating sphere, a coupling light path, and a spectrometer;
an inner wall of the integrating sphere is arranged with a composite light source consisting of eight LEDs; a sphere wall of the integrating sphere defines an incident aperture; light emitted from each LED enters an interior of the integrating sphere through the incident aperture and is irradiated onto the inner wall of the integrating sphere;
the coupling light path is configured to couple light at a measurement caliber such that the light can enter an incident split and to eliminate stray light from the inner wall of the integrating sphere; and
after emitting out from an observation aperture of the integrating sphere, the light enters the incident split through the coupling light path and is irradiated onto a linear-array sensor after being split by a spectral light path; and different pixels of the linear-array sensor correspond to light radiation strengths at different wavelengths.

2. The spectrophotometric colorimeter based on LED light source of claim 1 , wherein an upper semi-sphere of the integrating sphere is a regular semi-sphere, a lower semi-sphere of the integrating sphere is shaped as a cone, and a cone angle is equal to 45 degrees from a normal of a bottom surface of the cone.

3. The spectrophotometric colorimeter based on LED light source of claim 1 , wherein a diameter of the integrating sphere is 45 nm, and a size of the incident split of the spectrometer is 75*750 um.

4. The spectrophotometric colorimeter based on LED light source of claim 1 , wherein a finger of a reference white plate is arranged at a measurement opening of the integrating sphere, a side surface of the reference white plate corresponding to the integrating sphere is a standard white plate; when the reference white plate is opened, a measured sample is measured; when the integrating sphere is closed, the reference white plate is measured.

5. The spectrophotometric colorimeter based on LED light source of claim 1 , further comprising a driving device, the driving device is driven by a stepmotor, and the linear-array sensor is controlled to rotate over 180 degrees by the stepmotor.

6. The spectrophotometric colorimeter based on LED light source of claim 5 , wherein a step angle of the stepmotor is equal to 1.8 degrees; a signal is sampled each time the stepmotor rotates by 18 degrees; the signal is sampled ten times in each measurement, and the average of the sample values is used as a sample result.

7. A method for realizing a spectrophotometric colorimeter based on LED light source of claim 1 , comprising the following steps:
S 1 , light emitting from each LED entering the interior of the integrating sphere through the incident aperture and then being irradiated onto the inner wall of the integrating sphere; and
S 2 , after emitting out from an observation aperture of the integrating sphere, the light entering the incident split of the spectrometer through the coupling light path and being irradiated onto the linear-array sensor after being split by the spectral light path, in which different pixels of the linear-array sensor corresponding to light radiation strengths at different wavelengths.

8. The method of claim 7 , wherein the step S 2 further comprises:
driving a first gear to rotate through a stepmotor, driving a second gear to rotate through the first gear, driving a mounting plate of the linear-array sensor to rotate via pillow by the second gear; sampling a signal each time the stepmotor rotates by 18 degrees to obtain a sample signal, sampling the signal ten times in each measurement, and taking the average of the sample values as the sample result.

9. The method of claim 7 , further comprising the following step before step S 1 :
measuring the wavelength accuracy by a standard instrument to obtain a correspondence between a peak wavelength of the spectrophotometric colorimeter and the corresponding pixel of the sensor as Equation One shown below:
λ= k*n+d;   Equation One

wherein λ is the peak wavelength, k is a scale factor, d is a constant, and n is a serial number of the pixel.

10. The method of claim 9 , further comprising the following step before step S 1 :
measuring the wavelength accuracy after the spectrophotometric colorimeter is affected by an ambient factor to obtain a new correspondence between the peak wavelength and the corresponding pixel of the sensor as Equation Two shown below:
λ LED =k′*n+d′;   Equation Two

wherein k′ is a new scale factor, and d′ is a new constant;
revising Equation One according to Equation Two by replacing parameters k and d in Equation One with parameters k′ and d′ in Equation Two;
revising process comprises: each time when the spectrophotometric colorimeter is started, measuring a standard white plate; respectively turning on LED 1 with the peak wavelength thereof being 400 nm, LED 3 with the peak wavelength thereof being 430 nm, LED 5 with the peak wavelength thereof being 500 nm, LED 6 with the peak wavelength thereof being 700 nm in the measurement, measuring reflection light signals from the standard white plate to obtain the pixels of the linear-array sensor corresponding to the peak wavelengths n LED1 , n LED3 , n LED5 , n LED6 } of LED 1 , LED 3 , LED 5 , and LED 6 ;
fitting the two groups of data using the least square method to obtain Equation Three as follows:

(

λ

LED
⁢

⁢
1

,

λ

LED
⁢

⁢
3

,

λ

LED
⁢

⁢
5

,

λ

LED
⁢

⁢
6

)

T

=

k
′

*

(

n

Assignees

• Hangzhou Chnspec Technology Co Ltd
• Univ Jiliang China

Inventors

• Yuan Kun
• Wu Yiping
• Wang Cong
• Jin Shangzhong

Classifications

• G01J3/501

  Colorimeters using spectrally-selective light sources, e.g. LEDs · CPC title

• G01J3/02

  Details · CPC title

• G01J3/513

  having fixed filter-detector pairs · CPC title

• G01J3/0251 Primary

  Colorimeters making use of an integrating sphere · CPC title

• G01J3/524

  Calibration of colorimeters · CPC title