A method for measuring light energy transfer efficiency of an endoscope

Abstract

The application discloses a kind of endoscope light energy transfer efficiency measurement method, comprising the following steps: S1: using first photodetector to measure the first light signal emitted by illumination unit, obtain input signal;S2: the endoscope to be measured is installed in sample stage, using will second photodetector measure the second light signal emitted by the endoscope to be measured, obtain first output signal;S3: first output signal is processed to obtain second output signal, and input signal and second output signal are operated to obtain effective output signal;S4: imaging measurement device is placed in the exit pupil end of the endoscope to be measured to measure exit pupil field angle;S5: input signal, effective output signal and exit pupil field angle are used to calculate the light energy transfer efficiency of the endoscope to be measured.The application is based on the correlation function operation of two kinds of signals, can obtain effective output signal, reduce noise, obtain accurate light energy transfer efficiency test result.

Description

Technical Field

[0001] This invention relates to the field of photoelectric testing, and more specifically to a method for measuring the light energy transmission efficiency of an endoscope. Background Technology

[0002] A medical endoscope is a medical optical device that can be inserted into the body cavities and organs for direct observation, diagnosis, and treatment. Through the endoscope, medical personnel can directly observe lesions, collect diseased tissue, and remove pathogens, offering advantages such as a wide field of view, ease of operation, small diameter, and minimal trauma. Light energy transmission efficiency is one of the important parameters for evaluating the performance of a medical optical endoscope system. For medical endoscopes, light energy transmission efficiency also affects the safety and effectiveness of the equipment; therefore, light energy transmission efficiency testing is necessary for medical endoscopes. Currently, standards for testing the light energy transmission efficiency of medical endoscopes are divided into two types:

[0003] The first method: The light energy transfer efficiency of the optical observation mirror is the ratio of the average light exitance of the object surface to the average illuminance of the fundus image surface. It is necessary to measure the light flux at the exit pupil of the endoscope and the brightness value of the cosine radiation screen, then use a telescope to measure and calculate according to formula (1). The light energy transfer efficiency, D, is obtained by calculating through formula (2). M .

[0004]

[0005]

[0006] Where Y' is the length (mm) of the maximum effective scale of the micrometer telescope's image field of view, f' is the focal length (mm) of the micrometer telescope objective lens, and L is the object surface brightness of the cosine radiator, in cd / m². 2 Ф represents the luminous flux of the exit pupil of the optical observation lens, measured in lm.

[0007] The second type: The light energy transfer efficiency of non-visual optical observation mirrors is the lowest object surface brightness (L) that is critically recognizable in the image plane grayscale display. min Place the cosine radiation screen perpendicular to the endoscope, adjust the light intensity until the black mark line on the observation screen is almost indistinguishable, and measure the screen brightness. The brightness of the low-object surface (L) min This is the measured light energy transfer efficiency.

[0008] When the above-mentioned light energy transfer efficiency testing method is applied to the testing process of medical endoscopes, the following problems exist in the measurement of optical observation mirrors: Due to the diversity of the usage scenarios of medical optical endoscopes, the shape and diameter of the endoscopes vary when used in different parts of the human body. The effective working diameter of common optical mirrors is φ2mm~φ10mm. For this type of medical optical endoscope, the mirror body has the characteristic of small diameter. At the same time, the light attenuation effect of the optical lenses inside the mirror results in a weak light signal at the exit pupil, and even the background noise is stronger than the effective signal. Therefore, the signal-to-noise ratio at the eyepiece end is low, making it extremely difficult to measure accurately.

[0009] In summary, considering the extremely small order of magnitude of the effective light signal measurement value in actual testing, and the accuracy of measuring the weak light signals involved in the testing process, and the fact that the existing standard for optical endoscope light energy transfer testing methods cannot meet the current requirements, a method for measuring the light energy transfer efficiency of endoscopes is proposed to improve the accuracy of measurement results for medical endoscopes. Summary of the Invention

[0010] To address the shortcomings of existing technologies, this invention provides a method for measuring the light energy transmission efficiency of an endoscope, aiming to solve the problem that the effective light signal measurement value is extremely small in existing tests, affecting the accuracy of the measurement.

[0011] The specific technical solution of the present invention is as follows:

[0012] A method for measuring the light energy transmission efficiency of an endoscope, characterized in that the measurement system includes an illumination unit, a sample stage for loading and positioning the endoscope under test, an imaging measurement device, a first photodetector, a second photodetector, and a signal processing control unit. The measurement system is used to measure the optical performance parameters of the endoscope under test, such as... Figure 1 As shown, the specific steps include:

[0013] S1: Use the first photodetector to measure the first light signal emitted by the illumination unit to obtain the input signal;

[0014] S2: Install the endoscope under test on the sample stage, adjust the relative position of the illumination unit and the endoscope under test so that the endoscope under test is aligned with the illumination unit and the entrance pupil end of the endoscope under test is perpendicular to the light-emitting surface of the illumination unit, fix the second photodetector on the exit pupil end of the endoscope under test, measure the second light signal emitted from the illumination unit and emitted through the endoscope under test, and obtain the first output signal.

[0015] S3: Delay the first output signal to obtain the second output signal, perform correlation function operation on the input signal and the second output signal, and analyze and process the operation result to obtain the effective output signal;

[0016] S4: Place the imaging measurement device at the exit pupil end of the endoscope under test to measure the exit pupil field of view of the endoscope under test;

[0017] S5: The light energy transfer efficiency of the endoscope under test is calculated using the input signal, the effective output signal, and the exit pupil field angle.

[0018] Furthermore, step S1 specifically includes, in the measurement system, using a first photodetector to measure the first light signal emitted by the illumination unit, and recording the obtained input signal as x1(t), wherein the input signal includes a valid input signal s1(t) and a noise input signal n1(t), i.e., x1(t) = s1(t) + n1(t).

[0019] In the above technical solution, step S2 specifically includes using a second photodetector to measure the second light signal emitted from the illumination unit and emitted through the endoscope under test, and recording the obtained first output signal as x2(t). The first output signal includes a first effective output signal s2(t) and a first noise output signal n2(t), i.e., x2(t) = s2(t) + n2(t). Since the system composed of the multi-lens group of the endoscope under test is a linear system, the effective input signal s1(t) and the first effective output signal s2(t) are linearly related, which can be recorded as s2(t) = ks1(t), where k is a coefficient. The signal-to-noise ratio of the measured first effective output signal is low.

[0020] In the above technical solution, step S3 specifically includes: delaying the first output signal x2(t) to obtain a second output signal x2(t+τ), the second output signal x2(t+τ) including a second valid output signal s2(t+τ) and a second noise output signal n2(t+τ), i.e., x2(t+τ) = s2(t+τ) + n2(t+τ); using the input signal and the second output signal as the two input terminals of the multiplier respectively, performing correlation function operations on the two signals, according to the formula... The correlation function R(τ) of the input signal and the second output signal is calculated.

[0021] It should be noted that, in the above technical solution, the correlation function R(τ) of the input signal and the second output signal is composed of the correlation function of the effective input signal s1(t) and the second effective output signal s2(t+τ). The correlation function between the noisy input signal n1(t) and the second effective output signal s2(t+τ) The correlation function between the effective input signal s1(t) and the second noise output signal n2(t+τ) The correlation function between the noise input signal n1(t) and the second noise output signal n2(t+τ) Composition, believed Based on the correlation between the effective input signal and the second effective output signal, the correlation between the effective input signal and the second noise output signal, the correlation between the noise input signal and the second effective output signal, and the correlation between the noise input signal and the second noise output signal, R(τ) can be analyzed and processed to remove noise, resulting in the correlation function between the effective input signal s1(t) and the second effective output signal s2(t+τ).

[0022] In some specific implementations, the effective input signal and the second noise output signal, as well as the noise input signal and the second effective output signal, do not have the same waveform or frequency, and are uncorrelated. Therefore, when performing correlation function calculations on the effective input signal and the second noise output signal, and the noise input signal and the second effective output signal, the correlation function of both is 0, i.e. The noise input signal and the noise output signal are also irregular; therefore, the noise input signal n1(t) and the second noise output signal n2(t+τ) are uncorrelated, and their correlation function is... It can be considered that the correlation function R(τ) between the input signal and the second output signal is equivalent to the correlation function between the effective input signal s1(t) and the second effective output signal s2(t+τ).

[0023] In the above technical solution, S3 further includes classifying the input signal:

[0024] The first scenario: If the effective input signal s1(t) is a constant signal, denoted as C0, then the first effective output signal is also a constant signal. Since the effective input signal s1(t) and the first effective output signal s2(t) are linearly related, the first effective output signal can be denoted as kC0. The second effective output signal s2(t+τ) obtained after delaying the first output signal is the same as the first effective output signal s2(t), also denoted as kC0. According to the formula... Perform correlation function processing on the input signal and the second output signal and remove noise to obtain... It is linearly correlated with the square of the effective input signal; according to the correlation function of the effective input signal s1(t) and the second effective output signal s2(t+τ). Given the effective input signal s1(t), the first effective output signal s2(t) after noise removal, i.e., the kC0 value, is calculated. It should be noted that, due to the high signal-to-noise ratio of the input signal in this technical solution, it can be directly measured by the first photodetector.

[0025] The second scenario: If the effective input signal s1(t) is a periodic signal, then the effective input signal, the first effective output signal, and the second effective output signal all have the same period; according to the correlation function... The period T of the second effective output signal s2(t+τ) is obtained, and the period of the second output signal is also T. The first output signal values ​​(N>1) for N periods are taken, and the first output signals in phase are summed and averaged. After N averagings, the power of the uncorrelated first noise output signal is reduced to 1 / N, while the power of the first effective output signal remains unchanged, thus improving the signal-to-noise ratio (SNR) of the first output signal. Finally, the noise-reduced first effective output signal s2(t) is calculated. Alternatively, the second output signal values ​​(N>1) for N periods can be taken, and the second output signals in phase are summed and averaged. After N averagings, the power of the uncorrelated second noise output signal is reduced to 1 / N, while the power of the second effective output signal remains unchanged, thus improving the SNR of the second output signal. Finally, the noise-reduced second effective output signal s2(t+τ) is calculated, and thus the first effective output signal s2(t) is obtained.

[0026] When the effective input signal is a constant signal, the light energy transfer efficiency of the endoscope under test is calculated by combining the first effective output signal s2(t) obtained by the above step S3 with the input signal and the exit pupil field angle of the endoscope under test.

[0027] In the above technical solution, S5 specifically includes using an electro-optic modulator to convert the first effective output signal obtained after signal processing into a third optical signal, using a third detector to perform measurement to obtain a measurement value, and calculating the optical performance parameters of the endoscope under test based on the measurement value, the exit pupil field of view, and the input signal value.

[0028] In the above technical solution, step S4 specifically includes: placing the reticle on the illumination unit, adjusting the relative position of the reticle and the endoscope under test so that the endoscope under test is aligned with the reticle and the entrance pupil end of the endoscope under test is perpendicular to the center of the reticle, placing the imaging measuring device at the exit pupil end of the endoscope under test, and measuring the exit pupil field of view of the endoscope under test.

[0029] The beneficial effects of this invention are as follows: This invention proposes a method for measuring the light energy transmission efficiency of an endoscope. By performing correlation function operations on the input signal and the second output signal, and analyzing and processing the operation results, an effective output signal is obtained. This method can accurately measure the effective output signal, effectively remove or reduce noise signals, improve the signal-to-noise ratio of the output signal, and ultimately effectively detect low-frequency weak signals submerged in noise signals. This effectively improves the accuracy of testing the light energy transmission efficiency of medical endoscopes, and helps to improve the product quality, safety, and reliability of medical endoscopes. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the measurement method of the present invention.

[0031] Figure 2 This is a schematic diagram of the measurement system structure in Embodiment 1.

[0032] Figure 3 This is a schematic diagram of the waveform curve of the input signal in Example 1.

[0033] Figure 4 This is a schematic diagram of the waveform curve of the effective output signal in Example 1.

[0034] Figure 5 This is a schematic diagram of the waveform curve of the input signal in Example 2.

[0035] Figure 6 This is a schematic diagram of the waveform curve of the effective output signal in Example 2. Detailed Implementation

[0036] Example 1:

[0037] This embodiment provides a method for measuring the light energy transmission efficiency of an endoscope, wherein the endoscope being measured is a discoscope. Figure 2 This is a schematic diagram of the measurement system structure in this embodiment. Figure 3 This is a schematic diagram of the waveform curve of the input signal. Figure 4 A schematic diagram of the waveform curve for an effective output signal.

[0038] like Figure 2 As shown, the measurement system includes an illumination unit 1, a sample stage 2 for mounting and positioning the endoscope under test, an imaging measurement device 3, a first photodetector 4, a second photodetector 5, and a signal processing and control unit 6. The illumination unit 1 is a transmission light source box, providing a stable brightness source and outputting a constant signal. The first photodetector 4 is a luminance meter, placed on the light-emitting surface of the illumination unit 1, used to directly receive and measure the optical performance parameters of the light-emitting surface of the illumination unit 1. The objective lens of the endoscope under test is aligned with the light-emitting surface of the transmission light source box 1; the imaging measurement device 3 is aligned with the eyepiece of the endoscope under test, or connected to the eyepiece of the endoscope under test. The imaging measurement device 3 is a micrometer telescope connected to a high-definition camera system, which is electrically connected to a display screen. The second photodetector 5 is connected to the eyepiece of the endoscope under test; the light beam emitted by the illumination unit 1 is received and measured by the second photodetector 5 after passing through the endoscope under test. In this embodiment, a semi-transparent and semi-reflective mirror can be placed in the emission direction of the illumination unit 1, so that part of the light beam enters the first photodetector 4 and part of the light beam enters the endoscope being measured, thereby achieving measurement.

[0039] The light energy transmission efficiency of the discoscope was measured using the above-mentioned measurement system, wherein the maximum width of the discoscope inserted into the human body was 3 mm. The measurement method specifically included the following steps:

[0040] A1: The first light signal emitted by the illumination unit is measured using the first photodetector. Since the illumination unit uses a stable brightness source, the output signal-to-noise ratio is high. Figure 3 As shown, the effective input signal C0 = 6.27 is directly measured by the luminance meter, and the input signal x1(t) = 6.27 + n1(t), where n1(t) is the noise input signal;

[0041] A2: Install the intervertebral disc endoscope on the sample stage, adjust the relative position of the illumination unit and the intervertebral disc endoscope so that the endoscope is aligned with the illumination unit and the entrance pupil of the endoscope is perpendicular to the emitting surface of the illumination unit. Fix the second photodetector integrating sphere spectrometer to the exit pupil of the endoscope and measure the second light signal emitted from the brightness source and emitted through the endoscope to obtain the first output signal. Then, use the signal processing control unit to delay the first output signal to obtain the second output signal x2(t+τ). Since the effective input signal and the first effective output signal are linearly related, the effective input signal and the second effective output signal are also linearly related. The second effective output signal is denoted as 6.27k. The second output signal x2(t+τ) = 6.27k + n2(t+τ), where n2(t+τ) is the second noise output signal and k is a coefficient.

[0042] A3: Perform correlation function calculations on the input signal and the second output signal. Analyze and determine the correlation between the effective input signal and the second noise output signal, the correlation between the noise input signal and the second effective output signal, the correlation between the noise input signal and the second noise output signal, and the correlation between the effective input signal and the second effective output signal. After removing noise, the correlation function R(τ) = 0.003931 is obtained. Based on the measured C0 = 6.27, combined with the formula... The calculated second effective output signal after denoising is s2(t+τ)=kC0=6.27×10. -4 Then the first effective output signal s2(t) = 6.27 × 10 -4 ,like Figure 4 As shown.

[0043] A4: Place the reticle on the illumination unit, adjust the relative position of the reticle and the discoscope so that the discoscope is aligned with the reticle and the entrance pupil of the discoscope is perpendicular to the center of the reticle. Place the imaging measurement device at the exit pupil of the discoscope and measure the exit pupil field of view of the discoscope.

[0044] A5: The light energy transfer efficiency of the intervertebral disc endoscope is calculated based on the measured first effective output signal, input signal, and exit pupil field of view.

[0045] Example 2:

[0046] This embodiment provides a method for measuring the light transmission efficiency of an endoscope. The endoscope being measured is a sinus endoscope, and the maximum width of the portion of the endoscope inserted into the human body is 4 mm. The schematic diagram of the device structure in this embodiment is the same as in Embodiment 1, except that the power supply used by the illumination unit provides a periodic fluctuating signal. Specifically, it includes the following steps:

[0047] B1: The first light signal emitted by the illumination unit is measured using a first photodetector. The illumination unit experiences periodic fluctuations due to the power supply. The obtained input signal is denoted as x1(t). The input signal includes a valid input signal s1(t) and a noisy input signal n1(t), i.e., x1(t) = s1(t) + n1(t); where the valid input signal s1(t) = 8.79 - 0.239cos(100πt) is a periodic signal. Figure 5 As shown;

[0048] B2: Install the sinus endoscope on the sample stage, adjust the relative position of the brightness source and the sinus endoscope so that the sinus endoscope is aligned with the illumination unit and the entrance pupil end of the sinus endoscope is perpendicular to the light-emitting surface of the illumination unit. Fix the second photodetector integrating sphere spectrometer to the exit pupil end of the sinus endoscope and measure the second light signal emitted from the brightness source and emitted through the sinus endoscope to obtain the first output signal x2(t). Then, use the signal processing control unit to perform delay processing on the first output signal to obtain the second output signal x2(t+τ). The second output signal x2(t+τ) includes the second effective output signal s2(t+τ) and the second noise output signal n2(t+τ), that is, x2(t+τ)=s2(t+τ)+n2(t+τ).

[0049] B3: Perform correlation function calculation on the input signal and the second output signal. By determining the correlation between the noise signal and the effective signal, and the correlation between different noise signals, the correlation function R(τ) of the input signal and the second output signal is obtained. This correlation function is equivalent to the correlation function of the effective input signal s1(t) and the second effective output signal s2(t+τ). Since R(τ) has the same period as the effective input signal, the first output signal, and the second output signal, the period T of the first output signal can be obtained from R(τ). The first output signal x2(t) is divided into N = 10 segments according to period T, and each segment is represented as x. 2，i (t+iT), where 0≤t≤0.02, 0≤i≤9, and i is an integer, is the average of 10 periodic signals added in phase:

[0050]

[0051] in, The signal value of the first effective output signal s2(t) after in-phase averaging is obtained by averaging 10 times, resulting in the signal value of the first output signal after in-phase averaging. The noise power is reduced to 1 / 10 of its original value, significantly improving the signal-to-noise ratio of the first output signal. Finally, the denoised first effective output signal s2(t) can be obtained, as shown below. Figure 6 As shown.

[0052] B4: Place the reticle on the illumination unit, adjust the relative position of the reticle and the sinus endoscope so that the sinus endoscope is aligned with the reticle and the entrance pupil end of the sinus endoscope is perpendicular to the center of the reticle. Place the imaging measurement device on the exit pupil end of the sinus endoscope and measure the exit pupil field of view of the sinus endoscope.

[0053] B5: The first effective output signal obtained after signal processing is converted into a third optical signal using an electro-optic modulator, and the third detector is used to measure it to obtain the measured value. The light energy transfer efficiency of the sinus endoscope is calculated based on the measured value, the exit pupil field of view, and the input signal value.

[0054] The specific embodiments of the present invention have been described above with reference to the accompanying drawings. However, those skilled in the art should understand that the above embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for measuring the light energy transmission efficiency of an endoscope, characterized in that, The measurement system includes an illumination unit, a sample stage for loading and positioning the endoscope under test, an imaging measurement device, a first photodetector, a second photodetector, and a signal processing control unit. The measurement system is used to measure the optical performance parameters of the endoscope under test, specifically including the following steps: S1: Use the first photodetector to measure the first light signal emitted by the illumination unit to obtain the input signal; S2: Install the endoscope under test on the sample stage, adjust the relative position of the illumination unit and the endoscope under test so that the endoscope under test is aligned with the illumination unit and the entrance pupil end of the endoscope under test is perpendicular to the light-emitting surface of the illumination unit, fix the second photodetector on the exit pupil end of the endoscope under test, measure the second light signal emitted from the illumination unit and emitted through the endoscope under test, and obtain the first output signal. S3: Delay the first output signal to obtain the second output signal, perform correlation function operations on the input signal and the second output signal, and analyze and process the operation results to obtain a valid output signal; step S3 specifically includes, for the first output signal... The second output signal is obtained by performing a delay process. The second output signal Including the second valid output signal Second noise output signal ,Right now Using the input signal and the second output signal as the two input terminals of the multiplier, respectively, a correlation function operation is performed on the two signals, according to the formula... The correlation function of the input signal and the second output signal is calculated. ; S4: Place the imaging measurement device at the exit pupil end of the endoscope under test and measure the exit pupil field of view of the endoscope under test; S5: The light energy transfer efficiency of the endoscope under test is calculated using the input signal, the effective output signal, and the exit pupil field angle.

2. The method for measuring the light energy transmission efficiency of an endoscope as described in claim 1, characterized in that, Step S1 specifically includes, in the measurement system, using a first photodetector to measure the first light signal emitted by the illumination unit, and recording the obtained input signal as... The input signal includes a valid input signal. and noise input signal ,Right now .

3. The method for measuring the light energy transmission efficiency of an endoscope as described in claim 2, characterized in that, Step S2 specifically includes using a second photodetector to measure the second light signal emitted from the illumination unit and emitted through the endoscope under test, and recording the obtained first output signal as... The first output signal includes a first valid output signal. and the first noise output signal ,Right now The valid input signal and the first valid output signal A linear relationship is formed, denoted as , where k is a coefficient.

4. The method for measuring the light energy transmission efficiency of an endoscope as described in claim 3, characterized in that, The correlation function of the input signal and the second output signal From valid input signal Second effective output signal Related functions Noise input signal Second effective output signal Related functions Valid input signal Second noise output signal Related functions Noise input signal Second noise output signal Related functions Based on the correlation between the effective input signal and the second effective output signal, the correlation between the effective input signal and the second noise output signal, the correlation between the noise input signal and the second effective output signal, and the correlation between the noise input signal and the second noise output signal, the following is considered: After analysis and processing to remove noise, the effective input signal is obtained. Second effective output signal Related functions .

5. The method for measuring the light energy transmission efficiency of an endoscope as described in claim 4, characterized in that, Noise input signal Second effective output signal Unrelated, its correlation function Valid input signal Second noise output signal Unrelated, its correlation function Noise input signal Second noise output signal Unrelated, its correlation function The correlation function between the input signal and the second output signal. Equivalent to a valid input signal Second effective output signal Related functions .

6. The method for measuring the light energy transmission efficiency of an endoscope as described in claim 4, characterized in that, Step S3 further includes classifying the input signal: (1) Valid input signal If the input signal is a constant signal C0, then the first effective output signal and the second effective output signal are the same, also constant signals, denoted as kC0; by performing correlation function processing on the input signal and the second output signal and removing noise, we obtain... Based on valid input signals Second effective output signal Related functions and valid input signals The first effective output signal after noise removal is calculated. (2) Valid input signal If the signal is periodic, then the periods of the valid input signal, the first valid output signal, the second valid output signal, the first output signal, and the second output signal are the same; according to the correlation function... Obtain the second valid output signal If the period is T, then the period of the first output signal is also T. Take the first output signal values ​​for N periods (N>1), sum the first output signals in phase, and take the average to calculate the first effective output signal after noise reduction. .

7. The method for measuring the light energy transmission efficiency of an endoscope as described in claim 6, characterized in that, When the effective input signal is a constant signal, the first effective output signal is calculated and processed according to step S3. By combining the input signal and the exit pupil field angle of the endoscope under test, the light energy transfer efficiency of the endoscope under test is calculated.

8. The method for measuring the light energy transmission efficiency of an endoscope as described in claim 1, characterized in that, S5 specifically includes using an electro-optic modulator to convert the first effective output signal obtained after signal processing into a third optical signal, using a third detector to perform measurement, obtaining a measurement value, and calculating the light energy transfer efficiency of the endoscope under test based on the measurement value.

9. The method for measuring the light energy transmission efficiency of an endoscope as described in claim 1, characterized in that, Step S4 specifically includes: placing the reticle on the illumination unit, adjusting the relative position of the reticle and the endoscope under test so that the endoscope under test is aligned with the reticle and the entrance pupil end of the endoscope under test is perpendicular to the center of the reticle, placing the imaging measuring device at the exit pupil end of the endoscope under test, and measuring the exit pupil field of view of the endoscope under test.

Images