SU1213357A1 - Colorimeter - Google Patents

Abstract

The invention relates to the field of spectral measurements, in particular to colorimetry, and can be used to determine the color of self-luminous radiation sources or reflective samples. In order to increase the accuracy of measurements, the contour of the spectral mask of the colorimeter M1) in the direction of dispersion is performed satisfying the equation Xr (Li) rM (K) KA., - x). Jо V l I (-L where I (- the current wavelength, A (L -, - X.) - hardware function of the monochromator; Xi (i), Xa (- |) - boundary coordinates of the mask area, within which D ( Rh) 0; ((11) is the addition function given at the points D; S (fi.) Is the spectral sensitivity of the photodetector. Zil. (O C

Description

The invention relates to spectral measurements, in particular to colorimetry, and can be used to determine the color of self-luminous radiation sources or reflective samples.

The purpose of the invention is to improve the measurement accuracy.

1 shows a colorimeter, a general view; figure 2 and 3 - types of hardware functions of the monochromator,

The colorimeter consists of an illuminator 1, a monochromator 2, a spectral poppy 3, and a photodetector 4. Monochromat 2 contains an output slit 5, a collimator 6, a dispersing element 7, and a camera lens 8.

The device works as follows.

The radiation flux from the object under study falls on the illuminator which creates uniform illumination in the plane of the exit slit. Next, the collimator lens directs a parallel beam of rays to the dispersing element. The lens converts the dispersed beams of rays of various dpin waves into a spectrum image in the plane of the spectral mask.

The radiation flux incident on the photodetector, p; is proportional to

g 480) KY (A-X) A (JL-X) cJijl o1x, t-call

where (e) is the spectral density of the radiation flux, and the external integral is taken over the entire mask.

Manner of integration, we get

taonm jM (x) jY (A) A (a-x) dx380 „m

 "OHM

-fY (l) J lWA (l-x) dxlcl.

8o „„

The photodetector signal is proportional to the expression;

Tionm

5 (11) T (D) | Star

I

Mr. Xi (I)

| m (x) A (LX, {)

(the dependence of the integration limits on the wavelength in the inner integral is due to dispersion)

13357

In order for the photodetector signal to be proportional to the color coordinate, the equality

 ° nmr}

 15 (l) Y (e) Im (x; A (-x) s (

. (

ten

20

35

40

HH1

78О

X, (D)

nm

- j h (D) V (L) dD - V,

“OHM where Y is the color coordinate.

It follows that the colorimeter, in order to accurately measure the coordinate of the color, must have a mask that satisfies the ratio

HaСa,)

MU) A (/ J; -X) dx. 5 (L-,)

R

(one)

Xi (Ai)

Since the addition function Y (L |) is given discretely, the equality (1) is written for the separate wavelengths D |,

Equations of type (1) are solved as follows. The value of M {.X) is specified at those points of the exit slit, where L (D, -X) 0. Next, based on the ratio of the values) and y (Lg), the value Mt is found) at those points 3Q of the exit slit, where A ( I, -l) 0 and A (Ig -) 0; Then the value M (, x) is also found at the points of the exit slit, where A () 0 and A (I-s-L) 0, and so on. to the final value of D (

This method is similar to the numerical differentiation of the equation C 1).

Example I. The colorimeter contains an illuminator, a monochromator, an output slit with a spectral mask and a photodetector, and the hardware function of the monochromator has the form corresponding to Fig.2.

Suppose that only a segment (380 nm 780 nm) of the exit slit is used to build the mask. Then the part of the apparatus function used in the construction of the mask can be described as L (ll) K (R-L), where K is a certain constant coefficient.

Equation (1) at the same time writes, with:

COND.)

50

JK (X-x) M (x) dx

5 (i.)

55 Double differentiated, we get:

M (l) s1CHU (L) / 5 (l)

dl

Thus, to accurately realize the addition curve, the mask in this device must be made in the form of the second derivative of the addition function (if you take 5 (e)}, while if the mask were made in the form of an addition curve, the device would fall error.

PRI mme R 2. The colorimeter contains the same elements as in Example 1, but the monochromator is close to ideal, i.e. the blurring of the monochromatic image of the infinitely narrow slit can be neglected. Then, if the entrance slit of the monochromator is of such dimensions that all its monochromatic images in the plane of the spectral mask overlap as shown in Fig. 3, the hardware function can be represented as follows:

G1.x & L. -)-{Oh..

Equation (I) takes the form Xg (

y / j i

(A-x) M (x) dX JH (K) dX. CDJ) °

Differentiating, we get d fllii

L s with L) J

M (D)

dl

Claims (1)

Invention Formula A colorimeter containing an illuminator, a monochromator, an output slit with a spectral mask and a photodetector, characterized in that, in order to improve the measurement accuracy, the contour of the spectral mask M (X,) in the direction of dispersion satisfies the XzCAi equation) 5m (x) A (L -.- x) with |) (| 7TT . V X.U,) where D (is the current wavelength; A (A - X) is a hardware function of the monochromator; X {D,), Xr (R) are the boundary coordinates the portion of the mask within which A (L; -) 0 V (R) is the addition function defined at the points D,; (spectral sensitivity of the photodetector. Spike FIG. 2 780HM 380 nn i Fig, 5 780 nm