JPH0820357B2 - 1-2 dimensional photometric device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photometric device used for two-dimensionally measuring a light transmittance distribution on a sample surface.

B. Conventional Technology There are basically two methods for measuring the distribution of optical characteristics on the sample surface. One is to use a device such as a scanning microphotometer, to two-dimensionally scan a sample with a light spot, and measure the sample transmitted light or reaction light using a single light receiving element. The other is a method of capturing an image of the sample surface with an image sensor. In these measurement methods, assuming that the same measurement time is used for both, assuming that the number of pixels on the sample surface is n, the light amount integration time per pixel in the scanning method is 1 / n of the method using the image sensor, and thus S / N ratio is Therefore, if the same S / N ratio is to be obtained, it takes n times as long, and the scanning method has a very low measurement efficiency. On the other hand, in the imaging method, the entire sample surface is illuminated at the same time, so the transmitted light or reaction light from one pixel is affected by the scattered light of the adjacent sample portion, and the accurate transmittance or reaction rate, etc. I can't get the value of. Therefore, when accurate measurement values are required, it is necessary to use a scanning method that is not affected by scattered light from adjacent portions.

C. Problems to be Solved by the Invention As described above, in the scanning method, since the measurement value at one point on the sample surface is not affected by the scattered light in the adjacent portion, an accurate measurement value can be obtained, but the measurement efficiency is low. However, in the method that uses the image sensor, the sample surface is uniformly illuminated at the same time, so the measurement time per pixel is long and the measurement efficiency is good, but the measured value at one point on the sample surface is It is affected, and there is a problem that it is difficult to obtain accurate measurement values. Therefore, according to the present invention, by irradiating the entire surface of the sample, the measurement efficiency is improved, and moreover, the measured value at one point on the sample surface is not affected by the scattered light in the adjacent portion, and an accurate photometric value can be obtained.
~ It is intended to provide a two-dimensional photometric device.

D. Means for solving the problem Each pixel on the sample surface is simultaneously illuminated with light modulated at slightly different frequencies, and the transmitted or reflected light of the sample is measured with a single light receiving element. Is processed and decomposed into frequency components to obtain photometric information for each pixel. Although the above explanation was given for the planar sample,
Of course, the same can be said for measurements along one line on the sample.

E. When each pixel on the sample surface is simultaneously illuminated with light modulated at a slightly different frequency, the transmitted light or reflected light of each pixel is modulated at the same frequency as the light illuminating the image. When such light is measured with a single light receiving element, a measurement signal in which light modulated at various frequencies is superimposed is obtained. Therefore, if this measurement signal is subjected to frequency analysis, an amplitude spectrum is obtained in which the horizontal axis represents the modulation frequency of each modulated light and the vertical axis represents the intensity of each modulated light. From the correspondence relationship between the modulation frequency and the pixel on the sample, The intensity information of the reflected light is obtained in the transmitted light region of each pixel. In this method, all pixels are illuminated during the measurement period, and the light amount integration is performed for all the pixels during the measurement period, so the measurement efficiency is good, and the scattered light of adjacent pixels has different modulation frequencies. The effect is removed in the process of data processing, and accurate photometric data can be obtained.

F. Embodiment FIG. 1 shows an embodiment of the present invention. A is an optical system of a microscopic photometer, 1 is an objective lens, 2 is a half mirror, 3 is an eyepiece lens, 4 is a lens for condensing light transmitted through the objective lens on the light receiving surface of the light receiving element 5, and the light receiving element 5 is a single lens. One light receiving element (such as a photomultiplier tube). S is a sample, and B is a sample illumination optical system. In the sample illumination optical system, 6 is a light source in which unit light sources e are two-dimensionally arranged on a plane,
Reference numeral 7 denotes a bundle of optical fibers, one end of each bundle is opposed to each unit light source e of the light source 6, and the other end of the bundle 7 in which these optical fibers are gathered is one light emission. The surface is f, and the condenser lens 8
Forms an image of the light emitting surface f on the sample S. C is a lighting circuit for controlling lighting of the light source 6, and 9 is a driver, and power amplifiers P1, P2 ... P _n corresponding to individual unit light sources e of the light source 6 and oscillators F1, F2 ... _Pn for driving these amplifiers. It consists of F _n . Oscillation frequency fo, f1 ... f _n-1 of the oscillator F1, F2 ... F _n is based on the fo f1 = fo + Δf, f2 = fo + 2Δf, f n-1 = fo + (n-1) Δf. That is, f1, f2, ... F _n-1 are sequentially increased by Δf. The light emitter is an LED or plasma display type gas discharge light emitting array. With the configuration of the illumination system described above, each point of the sample S is illuminated with light modulated at different frequencies. D is a photometric circuit, and the output of the light receiving element 5 is taken into the Fourier transform processor 13 via the preamplifier 10, the sampling circuit 11, and the A / D converter 12, and the output data of the Fourier transform processor 13 is the image forming circuit 14. Is converted into two-dimensional image data and displayed as an image by the CRT 15. This image display is a two-dimensional distribution image of the light transmittance of the sample S.

FIG. 2 shows the sample surface divided into pixels. In this figure
0, 1, ... N are pixels and have a one-to-one correspondence with each unit light source e of the light source 6 of FIG. 1, and the transmittance of each pixel portion of the sample is φ.
(I). Pixel 0 is illuminated with light modulated at frequency fo, 1 is illuminated with light modulated at fo + Δf, and pixel i is generally illuminated with light modulated at frequency fo + iΔf. Therefore, the transmitted light intensity of the pixel i portion of the sample is represented by φ (i) cos {2π (fo + iΔf) t + Pi} + Ki, and the output signal I (t) of the light receiving element 5 is an output signal corresponding to the transmitted light of each pixel. Because it will be Japanese , And the part of I (t) excluding the stationary part is φ
Since (i) is Fourier transformed with the frequency interval Δf, the original φ (i) can be obtained by subjecting the non-stationary part of I (t) to Fourier transform again. Since φ (i) is the transmittance of the pixel portions 0, 1 ... N of the sample, if the number of pixels arranged in a horizontal row is l, the data of φ (i) is divided into l matrixes. By arranging them in the above manner, a two-dimensional distribution image of the transmittance of the sample is formed. Image forming circuit of FIG.
Reference numeral 14 forms a two-dimensional distribution image of the above-mentioned transmittance from the φ (i) data obtained by the Fourier transform processor 13, and the two-dimensional distribution image is displayed on the CRT 15.

If the modulation signal of the light illuminating each pixel on the sample is in phase at the reference time t = 0 and is represented by cos2π (fo + iΔf) t, the photometric output I (t) of the sample transmitted light is the reference time. The shape is symmetrical around t = 0. Therefore, when the illumination light and the sample light are changing in the same phase as in the transmittance measurement, φ (i) can be demodulated if the photometric data after t = 0 is obtained. In this way, the photometric method that also pays attention to the phase information is useful for establishing a completely new type of photometric principle in fluorescence measurement. That is, it is possible to provide a feature that both the fluorescence intensity distribution and the fluorescence lifetime distribution can be measured simultaneously. Even if the phase of the illumination light of each pixel portion matches at the reference time and is represented by the above formula, the phase of each pixel does not match in fluorescence, and the amplitude spectrum obtained by Fourier transform of the photodetection signal is the fluorescence intensity. It represents the distribution, and the phase spectrum will give information related to the distribution of the fluorescence lifetime.

FIG. 3 shows the configuration of an optical system for measuring the reflectance or fluorescence of the sample surface. The parts corresponding to the respective parts in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. In the above-described embodiment, the light source is a two-dimensional array of light emitting elements, and the intensity of each light emitting element is changed at each frequency. A light source system may be configured with the element array. FIG. 4 shows an example of such a light source system using a mechanical shutter means. 16 is an array type optical modulator and 17 is a high-intensity discharge tube. Reference numeral 18 is an optical fiber bundle, and the light of the discharge tube 17 is condensed by the lens 19 on the end surface where the bundle is gathered. The other end of each fiber of the optical fiber bundle 18 is connected to an individual modulation element in the array type optical modulator. The light beams that have passed through the individual modulators are aggregated again by the optical fiber bundle 20, and the image of the aggregated end face 20f of the optical fiber bundle 20 is formed on the sample surface by the condenser lens. The individual modulation elements that constitute the array-type optical modulator 16 include those using electro-optical crystals and those using liquid crystals, as well as a plate having light transmission holes in the vertical and horizontal directions,
The shutter plate may be made to vibrate in front of each hole, and the shutter plate may be vibrated by an electromagnetic vibrator. FIG. 5 shows an example. X
The coordinate designating electrode group x and the Y coordinate designating electrode group y are opposed to each other with the liquid crystal 21 in between. Each electrode of the X coordinate designation electrode group x is connected to a high frequency oscillator F1, F2 ..., Each electrode of the Y coordinate designation electrode group y is connected to a high frequency oscillator F1, F2. It's biased. Since the applied voltage frequency of both electrodes is different at the intersection of both electrodes, the electric field strength fluctuates at the beat frequency, and since the liquid crystal cannot follow the high frequency, the transmittance changes at this beat frequency. Oscillator F
There is a difference of Δf between the frequencies of 1, F2 ...
There is a frequency difference of kΔf between each of 2 ... (k is the number of X coordinate designated electrodes). Therefore, the transmittance change frequency of the liquid crystal has a difference of Δf between adjacent pixels in the X-axis direction and a difference of kΔf in the Y-axis direction.

G. Effect Since the photometric device of the present invention has the above-described configuration and simultaneously illuminates the entire surface of the sample to perform the light amount integration for each pixel point at the same time, compared to sequentially scanning the pixel points, If the same measurement time is used, the light intensity integration time for each pixel point is doubled by the number of pixel points, so the S / N ratio is significantly improved compared to the scanning type 1 and 2D photometer, and the photometry of the imaging method In the case of the device, the photometric value of each part of the sample is affected by the scattered light of the adjacent part and cannot be obtained accurately, whereas the effect of the adjacent part is discriminated in the data processing by the difference in the modulation frequency of the illumination light. Therefore, an accurate photometric value can be obtained.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention, FIG. 2 is an exploded view of pixels on a sample surface, FIG. 3 is a side view of an optical portion of another embodiment of the present invention, and FIG. 4 is an illumination system. FIG. 5 is a perspective view of another embodiment of FIG. 5, and FIG. 5 is a perspective view of another example of the light modulating means. A: Photometer optical system, B: Illumination optical system, C: Lighting circuit, D: Photometric circuit, 6: Light source light emitter, 9: Driver, F1 ... Fn: Oscillator

Claims (1)

[Claims] 1. A plurality of unit light sources, a lighting circuit which is provided for each unit light source, and modulates emission intensity at frequencies different from each other, and each unit light source is associated with each pixel on the sample surface in a one-to-one correspondence with each unit. Means for guiding the light of the light source to the sample surface, one light receiving element for collectively receiving the light from each pixel on the sample surface, means for Fourier-converting the output of the light-receiving element, and the sample for the Fourier-converted output A one- to two-dimensional photometric device comprising means for displaying an image of the Fourier transform output by making a portion corresponding to the modulation frequency of light from each pixel on the surface correspond to the corresponding pixel on the sample surface.