JPS635234A - Unidimensional-two-dimensional photometric apparatus - Google Patents

Abstract

PURPOSE:To enhance measuring efficiency and to perform accurate measurement such that the measured value at one point on the surface of a specimen being free of effect of the scattering light of the adjacent part, by irradiating the entire surfaces of the picture elements on the surface of the specimen with lights modulated by frequencies different from each other gradually. CONSTITUTION:The light emitting intensities of the indivisual light emitting regions of a light source 6 wherein minute light emitters (e) are arranged on a plane two-dimensionally are modulated by frequencies different from each other gradually and light is allowed to simultaneously illuminate the picture elements on the surface of a specimen through an optical fiber bundle 7. The transmitted or reflected light of each picture element is modulated by the same frequency as the light illuminating said picture element. When this modulated light is measured by a single light receiving element 5 through an objective lens, 1, a measuring signal wherein lights modulated by various frequencies are superposed is obtained. When the frequency of this measuring signal is analyzed by a photometric circuit comprising a Fourier transformer processor 13, an amplitude spectrum wherein the modulation frequencies of respective modulated lights are taken on a transverse axis and the intensities of the modulated lights are taken on a vertical axis is obtained and, from the corresponding relation between the modulation frequencies and the picture elements on the specimen, the intensity of the transmitted or reflected light of each picture element is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a photometric device used for two-dimensionally measuring the light transmission weight distribution on a sample surface.

BACKGROUND OF THE INVENTION In principle, there are two methods for measuring the distribution of optical properties on a 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 light transmitted or reflected from the sample using a single light-receiving element. Another method is to capture an image of the sample surface using an image sensor. Assuming that both of these measurement methods take the same measurement time, and the number of pixels on the sample surface is n, the light intensity integration time per pixel in the scanning method is 1/n of that in the method using an image sensor, and therefore the S/ N ratio is 115
Therefore, if an attempt is made to obtain the same S/N ratio, it will take n times as much time, and the measurement efficiency of the scanning method is extremely low. On the other hand, in the imaging method, the entire sample surface is illuminated at the same time, so the transmitted light or reflected light from one pixel is affected by the scattered light from adjacent sample parts, so it is difficult to determine the exact transmittance or reflectance. value cannot be obtained. Therefore, if accurate measurement values are required, it is necessary to use a scanning method that is not affected by scattered light from adjacent parts.

C1 Problems to be Solved by the Invention As mentioned above, in the scanning method, the measured value at one point on the sample surface is not affected by the scattered light from adjacent parts, so accurate measured values can be obtained, but the measurement efficiency is low. However, in the method using an image sensor, the sample surface is uniformly irradiated at the same time, so the measurement time per pixel is long (measuring efficiency is good, but the measured value of one point on the sample surface is different from that of adjacent parts). There is a problem in that it is difficult to obtain accurate measurement values due to the influence of scattered light.

Therefore, the present invention improves measurement efficiency by irradiating the entire surface of the sample, and moreover, the measurement value at one point on the sample surface is not affected by the scattered light from adjacent areas, so that an accurate photometric value can be obtained.
The present invention aims to provide a dimensional photometry device.

21.Means for solving the problem: illuminating each pixel on the sample surface simultaneously with light modulated at slightly different frequencies, and measuring the transmitted light or reflected light from the sample with a single light-receiving element; The photometric data is processed and decomposed into frequency components to obtain photometric information for each pixel. Although the above explanation has been made regarding a planar sample, it goes without saying that the same can be said about measurement along one line on the sample.

When each pixel on the sample surface is illuminated at the same time with light modulated at slightly different frequencies, the transmitted light or reflected light of each pixel will be modulated at the same frequency as the light that illuminated 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, by frequency-analyzing this measurement signal, an amplitude spectrum with the modulation frequency of each modulated light on the horizontal axis and the intensity of each modulated light on the vertical axis can be obtained, and from the correspondence between the modulation frequency and the pixels on the sample, , intensity information of transmitted light or reflected light of each pixel can be obtained. In this method, all pixels are illuminated during the measurement period, and light intensity integration is performed for all pixels during the measurement period, so measurement efficiency is good, and the scattered light of adjacent pixels has different modulation frequencies, so This effect is removed during data processing, resulting in highly accurate photometric data.

Embodiment FIG. 1 shows an embodiment of the present invention. A is the optical system of the microphotometer, 1 is an objective lens, 2 is a half mirror, 13 is an eyepiece, 4 is a lens that focuses the 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 one. A light-receiving element (such as a photomultiplier tube). S is the sample;
B is a sample illumination optical system. In the sample illumination optical system,
6 is a light source in which minute light emitters e are two-dimensionally arranged on a plane; 7
is a bundle of optical fibers, one end of each of the bundles faces each light emitting body e of the light source 6, and the other end of the bundle 7 where these optical fibers are gathered forms one light emitting surface. f, and the condenser lens 8 forms an image of this light emitting surface f on the sample S.

C is a lighting circuit that controls the lighting of the light source 6; 9 is a driver; power amplifiers PL, P2...pn corresponding to the individual minute light emitters e of the light source 6; and an oscillator Fl that drives these amplifiers; It consists of F2...Fn.

Oscillator F1. F2...Fn oscillation frequency fo.

fl...fn-+ is based on fo, fl=fo+
Δf, f2=fo+2Δf.

fn-+ = fo + (11-+)Δf. That is, fl, f2. . . . f n-1 increases by Δ" in order. The light emitter is an LED or a plasma display type gas discharge light emitting array. Due to the configuration of the illumination system described above, each point on the sample S is It is illuminated by light modulated at different frequencies.D is a photometric circuit, and the output of the light receiving element 5 is sent to a Fourier transform processor 13 via a preamplifier 10, a sampling circuit 11, and an A/D converter 12. The output data of the Fourier transform processor 13 is converted into two-dimensional image data in the image forming circuit 14, and the image is displayed on the CRT 15. This image display is a two-dimensional distribution image of the light transmittance of the sample S.

Figure 2 shows where the sample surface is divided into pixels. 0 in this diagram
,1. . . . n is a pixel, which corresponds one-to-one with each microscopic light emitter e of the light source 6 in FIG. 1, and the transmittance of each pixel portion of the sample is φ(i). Pixel O is illuminated with light modulated at frequency fO, 1 is illuminated with light modulated at fO+Δf, and - in general, pixel i is illuminated with light modulated at frequency fo+iΔf. Therefore, the transmitted light intensity of the part of pixel i of the sample is expressed as, and the output signal 1 (t) of the light receiving element 5 is the sum of the outputs corresponding to the transmitted light of each pixel.
The part of (t) excluding the stationary part is the Fourier transform of φ(i) at the frequency interval Δf, so I
If the unsteady part of (t) is Fourier transformed again, the original φ
(i) is found. φ(i) is the pixel portion of the sample 0.1...
・Since the transmittance is n, the number of horizontal rows of pixels is e
Then, if the data of φ(i) is divided into e pieces and arranged in a matrix, a two-dimensional distribution image of the transmittance of the sample will be formed. The image forming circuit 14 in FIG. 1 forms a two-dimensional distribution image of the transmittance, etc. described above from the φ(i) data obtained by the Fourier transform processor 13, and the two-dimensional distribution image is displayed on the CRT 15. It is.

Now, the modulation signal of the light that illuminates each pixel on the sample is the reference point 1.
If the phases match at =0 and are expressed as cOozyr(I.+It4Jt), the photometric output I(1) of the light transmitted through the sample will be symmetrical with respect to the reference time 1=0.Therefore, the transmitted light When the illumination light and sample light are changing in the same phase, such as in rate measurement, φ(i) can be demodulated if photometric data after 1=0 is obtained.In this way, phase information can be A photometric method that focuses on this is useful for establishing a completely new type of photometric principle in fluorescence measurement.In other words, it has the advantage of being able to measure both the fluorescence intensity distribution and the fluorescence lifetime distribution at the same time. Even if the phase of the illumination light of each pixel part matches at the reference time point and is expressed by the above equation, in fluorescence, the phase of each pixel does not match, and the amplitude spectrum obtained by Fourier transforming the photodetection signal is the fluorescence intensity. distribution, and the phase spectrum provides information related to the distribution of fluorescence lifetime.

FIG. 3 shows the configuration of an optical system for measuring reflectance or fluorescence on a sample surface. Components corresponding to those in FIG. 1 are designated by the same reference numerals, so explanations thereof will be omitted. In the above embodiment, a two-dimensional array of light emitting elements is shown as a light source,
Although the configuration is such that the intensity of each light emitting element is changed at each frequency, the light source system may be configured with a spread light source and a pixel-divided light modulation element array facing the light source. 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. 18 is an optical fiber bundle,
The light from the discharge tube 17 is focused by a lens 19 on the end face thereof. The other end of each fiber of the optical fiber bundle 18 is connected to a respective modulation element in the array type optical modulator. The light that has passed through each modulation element □ is again collected by the optical fiber bundle 20, and an image of the collected end face 20f of the optical fiber bundle 20 is formed on the sample surface by a condenser lens. The individual modulation elements that make up the array type optical modulator 16 include those that use electro-optic crystals and liquid crystals, as well as those that use a plate with light transmission holes vertically and horizontally, and vibrate on the front surface of the plate. The shutter plate may have a structure in which the shutter plate is vibrated by an electromagnetic pie-break. Fifth
An example is shown in the figure. An X coordinate designating electrode group X and a Y coordinate designating electrode group y are opposed to each other with the liquid crystal 21 in between. Each electrode of the X coordinate designated electrode group X is connected to a high frequency oscillator F1. F2
. . , each electrode of the Y coordinate designating electrode group y is connected to a high frequency oscillator fl, f2, . . . , and a constant DC bias is applied between the picture electrode groups. At the intersection of the two electrodes, the voltage frequency applied to the two electrodes is different, so the electric field strength diminishes at the beat frequency, and since the liquid crystal cannot follow high frequencies, the transmittance changes at this beat frequency. Oscillator Fl, F2・
There is a difference of Δf between the frequencies of the oscillators f1,
There is a frequency difference of Δf between each of f2... (k
is the number of electrodes specified by the X coordinate). Therefore, in the transmittance change frequency of the liquid crystal, there is a difference of Δf between adjacent pixels in the X-axis direction, and a difference of Δf in the Y-axis direction.

G. Effect The photometric device of the present invention has the above-described configuration, and simultaneously illuminates the entire sample surface and performs light intensity integration for each pixel point at the same time, compared to sequentially scanning the pixel points. However, if the same measurement time is used, the time for integrating the light intensity for each pixel point is doubled by the number of pixel points, and therefore the S/N ratio is significantly improved compared to scanning type one- and two-dimensional photometers, and the imaging method In the case of a photometric device, the photometric value of each part of the sample cannot be determined accurately because it is affected by the scattered light of adjacent parts, whereas the influence of adjacent parts is discriminated in data processing due to the difference in the modulation frequency of the illumination light. Therefore, accurate photometric values can be obtained.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of one embodiment of the present invention, Fig. 2 is a pixel exploded diagram of the sample surface, Fig. 3 is a side view of the optical part of another embodiment of the present invention, and Fig. 4 is an illumination system. FIG. 5 is a perspective view of another example of the light modulation means.

Claims (1)

[Claims] a light source having a one- to two-dimensional array; a means for modulating the emission intensity of each light emitting area of the light source at different periods;
means for projecting light from each light-emitting region of the light source onto corresponding pixel portions on the sample surface; a light-receiving element for collectively receiving light from each pixel portion of the sample; and means for frequency-analyzing the output of the light-receiving element. A one- to two-dimensional photometric device.