Light source device
Patent Information
- Application Number
- JP2023040587
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-03-15
- Publication Date
- 2026-02-17
AI Technical Summary
Existing light source devices for imaging diagnosis, such as those used in fundus cameras, suffer from insufficient intensity uniformity and increased cost due to separate notch filters and dichroic mirrors, which hinder size and weight reduction.
A light source device combining laser and LED light sources with a phosphor, notch filter, and dichroic mirror configuration that attenuates primary fluorescence and combines secondary fluorescence with LED light to achieve uniform intensity across a desired wavelength range.
The configuration ensures uniform intensity of combined light across a desired wavelength range, avoiding intensity loss and reducing device size and cost by optimizing the arrangement of optical elements.
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Abstract
Description
[Technical field]
[0001] The present invention relates to a light source device used, for example, for illumination of an imaging diagnostic apparatus. [Background technology]
[0002] For example, it is desirable for illumination light used in imaging diagnosis using a fundus camera to have a uniform intensity (amount of light) within a predetermined wavelength range.
[0003] For example, it is desirable for illumination light used in imaging diagnosis using a fundus camera to have a uniform intensity (amount of light) within a predetermined wavelength range.
[0004] Patent Document 1 discloses a light source device for an endoscope. According to this light source device, fluorescent light and an LED light source are multiplexed by a dichroic mirror, and then emitted after passing through a notch filter.
[0005] Patent Document 2 discloses a biological particle evaluation device equipped with a light source device that irradiates particles to be measured. According to this biological particle evaluation device, the laser light emitted from the laser light source of the light source device is branched into detection light at a detection point provided in the middle of the optical path to detect the amount of light. The branched detection light passes through a notch filter and is then split by a dichroic mirror. [Prior art documents] [Patent documents]
[0006] [Patent Document 1] JP 2015-171442 A [Patent Document 2] Patent No. 5681600 Summary of the Invention [Problem to be solved by the invention]
[0007] In the light source device of Patent Document 1, the fluorescence generated by the laser light and the LED light from the LED light source are first combined by a dichroic mirror and then pass through a notch filter. Therefore, the intensity of the LED light source is significantly reduced, i.e., insufficient, and the uniformity of the intensity of the combined light cannot be ensured in a sufficient wavelength range.
[0008] The dichroic mirror equipped in the light source device of Patent Document 2 is used to split light, not to combine it. The reason why the notch filter and the dichroic mirror are arranged in that order in the optical path of this light source device is that if the dichroic mirror is arranged upstream of the notch filter in the optical path, two notch filters would be required in total to process each split light, which would increase costs, and this is to avoid this, and has no relation to the uniformity of intensity.
[0009] The light source devices of Patent Documents 1 and 2 are both equipped with a notch filter and a dichroic mirror separately, which is disadvantageous in terms of reducing the size and weight of the light source device.
[0010] An object of the present invention is to provide a light source device that emits multiplexed light of fluorescent light generated by a laser light source and LED light, such that the spectrum of the multiplexed light is uniform within a desired wavelength range. [Means for solving the problem]
[0011] The light source device of the present invention comprises: a laser light source that emits laser light having a wavelength shorter than a first wavelength; a phosphor that is excited by the laser light and emits primary fluorescence having a wavelength longer than the first wavelength; a notch filter that emits secondary fluorescence obtained by attenuating the primary fluorescence from the phosphor in an attenuation wavelength range that includes a wavelength longer than the first wavelength; an LED light source that emits LED light having a wavelength shorter than the first wavelength; a dichroic mirror that outputs a combined light obtained by combining the secondary fluorescent light from the notch filter and the LED light from the LED light source; It is equipped with: Effect of the Invention
[0012] According to the present invention, the fluorescence generated by excitation of the laser light passes through a notch filter, is attenuated, and then is combined with the LED light at the dichroic mirror. As a result, while avoiding a situation in which the intensity of the LED light is insufficient due to passing through a notch filter, the secondary fluorescence is generated by reducing the intensity of the primary fluorescence using the notch filter, and the spectrum of the combined light can be made uniform in the wavelength range of the secondary fluorescence and the wavelength range of the LED light. [Brief description of the drawings]
[0013] [Figure 1] 1 is an overall view of a light source device used for imaging diagnosis using a fundus camera. [Diagram 2] FIG. 2 is a diagram showing the generation and flow of various lights in a light source device. [Diagram 3] 4A and 4B are diagrams illustrating the spectral characteristics of multiplexed light and each element in a light source device. [Figure 4A] FIG. 4 is a diagram showing the relationship between wavelength and transmittance for a dichroic mirror. [Figure 4B] FIG. 4 is a diagram showing the relationship between wavelength and transmittance for a notch filter. [Figure 4C] 11 is a diagram showing the relationship between wavelength and arbitrary intensity when laser light LDb emitted from a laser diode and primary fluorescence FL emitted from a phosphor are combined. FIG. [Figure 4D] FIG. 2 is a diagram showing the relationship between wavelength and arbitrary intensity of LED light LEb emitted by an LED. [Figure 4E] 1 is a diagram showing the relationship between the wavelength and an arbitrary intensity of laser light LDb emitted by a laser diode. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] Hereinafter, an embodiment of the present invention will be described. It goes without saying that the present invention is not limited to the embodiment. Note that the same reference numerals will be used throughout the drawings to designate components common to a plurality of embodiments.
[0015] (composition) FIG. 1 is an overall view of a light source device 10 used for imaging diagnosis by a fundus camera. The light source device 10 of the embodiment is used together with a fundus camera. The light source device 10 includes a laser diode 12 that emits blue laser light LDb, and an LED 30 that emits blue LED light LEb. The laser light LDb is converted into primary fluorescence FL1 and secondary fluorescence FL2 in order. Then, the combined wave of the secondary fluorescence FL2 and the LED light LEb is emitted to the outside from a slit 47 of a module case 46. Detailed characteristics of the laser light LDb, the LED light LEb, the primary fluorescence FL1, and the secondary fluorescence FL2 will be described with reference to FIG. 2 and FIG. 3.
[0016] The optical axis of the laser diode 12 extends in a straight line and passes through a slit 47 in a module case 46. Along this optical axis, a collimator lens 16, a phosphor 18, a collimator lens 22, an optical element 36, and a collimator lens 44 are arranged in this order from the laser diode 12 toward the slit 47. An LED 30 as a light source separate from the laser diode 12 is mounted on an LED substrate 31. The optical axis of the LED 30 reaches the optical element 36, and a collimator lens 32 is arranged on the optical axis between the LED 30 and the optical element 36.
[0017] The optical element 36 has a glass substrate 39, a notch filter 38 formed by film deposition on the glass substrate 39 on the incident surface side of the primary fluorescence FL1, and a dichroic mirror 40 formed by film deposition on the incident surface side of the glass substrate 39 on the LED light LEb. The optical element 36 is disposed at the intersection of both optical axes such that the normal to the surface on the notch filter 38 side and the normal to the surface on the dichroic mirror 40 side are inclined at 45° with respect to the optical axis of the laser diode 12 and the optical axis of the LED 30, respectively.
[0018] The photodetector 24 detects the intensity of the primary fluorescence FL1 emitted from the collimator lens 22. In detail, a hole is formed on the back side of the holder of the collimator lens 22 (the entrance surface and exit surface of the collimator lens 22 are called the front surface and back surface, respectively), and the photodetector 24 is inserted into this hole to detect the intensity of the LED light LEb. Similarly, the photodetector 34 is inserted into a hole on the back side of the holder of the collimator lens 32 to detect the intensity of the LED light LEb emitted from the collimator lens 32.
[0019] The light source driving device 50 controls the driving voltages of the laser diode 12 and the LED 30 based on the outputs of the photodetectors 24, 34. The intensity of the laser light LDb emitted by the laser diode 12 and the intensity of the LED light LEb emitted by the LED 30 increase or decrease depending on the driving voltages of the laser diode 12 and the LED 30, respectively.
[0020] The notch filter 38 is oriented so that the primary fluorescence FL1 is incident at an incident angle of 45°. As a result, the reflected light of the primary fluorescence FL1 that is reflected without being transmitted by the notch filter 38 (reflected fluorescence FLc, which will be described later in FIG. 2) is reflected in the direction perpendicular to the optical axis of the primary fluorescence FL1 toward the opposite side to the side where the photodetector 24 is disposed.
[0021] Fig. 2 is a diagram showing the generation and flow of various types of light in the light source device 10. Fig. 3 is a diagram showing the spectral characteristics of the multiplexed light and each element in the light source device 10. In Fig. 3, λ1, λ2, λ3, and λ4 are each predetermined wavelengths (values), with λ1<λ2<λ3<λ4. The solid line shows the spectrum of the multiplexed secondary fluorescence FL2 and LED light LEb as the output light of the dichroic mirror 40.
[0022] The target values are indicated by two dashed lines, upper and lower. The upper dashed target line indicates the minimum intensity that the combined spectrum must ensure in the wavelength range of λ3 (e.g., 500 nm)-λ4 (e.g., 610 nm). The lower dashed target line indicates the minimum intensity that the combined spectrum must ensure outside the wavelength range of λ3-λ4. Furthermore, the dashed dotted line and the dashed double dotted line indicate the transmittance characteristics of the notch filter 38 and the dichroic mirror 40, respectively.
[0023] In Fig. 3, λ1 (e.g., 460 nm) is the wavelength of maximum intensity of the LED light LEb emitted by the LED 30. λ2 is the wavelength of minimum intensity of the combined spectrum (e.g., a wavelength of 470 nm-480 nm). Note that the unit of intensity in Fig. 3 is arbitrary intensity (au).
[0024] 4A to 4E will be described first. FIG. 4A is a diagram showing the relationship between wavelength and transmittance for the dichroic mirror 40. The transmittance characteristics of the dichroic mirror 40 are divided into three parts: a lower flat region for short wavelengths where the transmittance is almost 0%, an upper flat region for long wavelengths where the transmittance is almost 100%, and a rising region between the two. λ2 in FIG. 3 corresponds to the wavelength at a point in the rising region that is almost 3db down from the upper flat region (e.g., a wavelength within 470nm-480nm).
[0025] 4B is a diagram showing the relationship between wavelength and transmittance for notch filter 38. The transmittance characteristics of notch filter 38 are in an attenuation region where the transmittance drops significantly in a predetermined wavelength range (for example, from about 500 nm to about 600 nm).
[0026] Fig. 4C is a diagram showing the relationship between wavelength and arbitrary intensity when the laser light LDb emitted from the laser diode 12 and the primary fluorescence FL1 emitted from the phosphor 18 are combined. The arbitrary intensity of the laser light LDb emitted from the laser diode 12 is concentrated in the vicinity of a wavelength λ of 450 nm, and in Fig. 4C, the arbitrary intensity is approximately 1.3, but in reality, it is larger than that and cannot be measured by the spectroscope, and the top is flat due to saturation.
[0027] Fig. 4D is a diagram showing the relationship between wavelength and arbitrary intensity for LED light LEb emitted by the LED 30. Fig. 4E is a diagram showing the relationship between wavelength and arbitrary intensity for laser light LDb emitted by the laser diode 12. The wavelength λ at which the arbitrary intensity is maximum is almost the same for the LED light LEb and the laser light LDb, but the wavelength width at which the arbitrary intensity is half of the peak is wide for the LED light LEb, whereas it is too narrow for the laser light LDb, and it can be seen that the minimum necessary intensity cannot be ensured in the wavelength range required for use in imaging diagnosis by a fundus camera in the wavelength range of λ2 or less.
[0028] Returning to Fig. 3, the transmittance characteristic of the dichroic mirror 40 (two-dot chain line) and the transmittance characteristic of the notch filter 38 (one-dot chain line) are the characteristics of Fig. 4A and Fig. 4B, respectively, transcribed into Fig. 3. The spectrum of the multiplexed secondary fluorescence FL2 and LED light LEb as the output light of the dichroic mirror 40 (solid line) is shown in Fig. 3 after multiplying the transmittance in Fig. 4B by the arbitrary intensity in Fig. 4C in the same wavelength range, and converting the intensity of each wavelength in the wavelength range of λ>λ2 to an arbitrary intensity so that the actual intensity corresponding to the maximum multiplication value coincides with the intensity corresponding to 1 of the arbitrary intensity in Fig. 4D.
[0029] 3, the intensities in both wavelength ranges of the combined spectrum are adjusted so that the maximum intensity in the wavelength range of λ<λ2 is equal to the maximum intensity in the wavelength range of λ>λ2. Also, the characteristics of notch filter 38 are set so that the intensity condition of being equal to or greater than the target value (upper dashed line) is satisfied, and the intensity condition of being equal to or greater than the target value (lower dashed line) outside the wavelength range of λ3-λ4 is satisfied.
[0030] (action) In Fig. 2, the laser diode 12 emits laser light LDb. This laser light LDb has a wavelength less than λ2 as blue coherence light, and has a higher intensity than the LED light LEb. As the laser light LDb passes through the phosphor 18, it is converted into primary fluorescence FL1. The wavelength of the primary fluorescence FL1 is λ2 or more. A portion of the laser light LDb passes through the phosphor 18 as it is without being converted into the primary fluorescence FL1.
[0031] The primary fluorescence FL1 and the laser light LDb reach the notch filter 38. The transmission characteristics of the notch filter 38 are as shown by the dashed line in Fig. 3. The notch filter 38 is disposed in the optical path of the primary fluorescence FL1, tilted at a predetermined tilt angle. The laser light LDb, whose wavelength is less than λ2, passes straight through the notch filter 38.
[0032] Furthermore, the primary fluorescence FL1, whose wavelength is equal to or greater than λ2, is separated by the notch filter 38 into reflected fluorescence FLc as reflected light and secondary fluorescence FL2 as transmitted light in accordance with the transmission characteristics of the notch filter 38. The emission direction of the reflected fluorescence FLc from the notch filter 38 is the opposite side to the arrangement side of the photodetector 24 in a predetermined perpendicular direction to the optical axis of the primary fluorescence FL1. The secondary fluorescence FL2 is emitted in a straight line from the notch filter 38 together with the laser light LDb, whose wavelength is less than λ2.
[0033] This secondary fluorescence FL2 corresponds to the spectral lines of λ2 or more in the combined spectrum (solid line) in Fig. 3. The reflected fluorescence FLc is changed in direction by 90° in the notch filter 38 and is reflected on the opposite side of the photodetector 24 with respect to the optical path of the primary fluorescence FL1. In other words, the reflected fluorescence FLc is reflected in a direction deflected from, preferably away from, the photodetector 24. As a result, the photodetector 24 is prevented from picking up the reflected fluorescence FLc and erroneously detecting the light amount of the primary fluorescence FL1.
[0034] The secondary fluorescence FL2 and the laser light LDb that have passed through the notch filter 38 reach the dichroic mirror 40. The transmission characteristics of the dichroic mirror 40 are as shown by the two-dot chain line in Fig. 3. Since the laser light LDb is light with a wavelength less than λ2, it is prevented from passing through the dichroic mirror 40 and is reflected in the same reflection direction as the reflected fluorescence FLc, which is a direction at 90° with respect to the optical axis on the incident side. Since the secondary fluorescence FL2 is light with a wavelength equal to or greater than λ2, it exits the dichroic mirror 40 in a straight line.
[0035] The surface of the dichroic mirror 40 from which the secondary fluorescence FL2 emerges is also the incident surface for the LED light LEb from the LED 30. Since the LED light LEb has a wavelength less than λ2, its direction is changed by 90° toward the collimator lens 44 in the dichroic mirror 40, where it is reflected and combined with the secondary fluorescence FL2 to be emitted toward the collimator lens 44. The combined spectrum (solid line) in Fig. 3 shows the relationship between the intensity and wavelength of this combined light.
[0036] The light source driving device 50 controls the driving voltages of the laser diode 12 and the LED 30 based on the detection signals of the photodetectors 24, 34 so that in the combined spectrum (solid line), the intensity in the wavelength range λ3-λ4 (500-600 nm) to which the secondary fluorescence FL2 contributes and the maximum intensity (the intensity at λ1 in the example of FIG. 3) in the wavelength range less than λ2 to which the LED light LEb contributes are both equal to an arbitrary intensity 1. Furthermore, at this time, the transmission characteristics of the notch filter 38 and the dichroic mirror 40 are set so that the arbitrary intensity of the combined spectrum at λ2 is ensured to be equal to or greater than the lower target value.
[0037] (Supplements and modifications) The light source device 10 is used as a light source device for imaging diagnosis using a fundus camera. The light source device of the present invention can also be applied as a light source device for an analysis device or an imaging device. The light source device 10 of the present invention is configured as one light source module, but it does not have to be configured as a module, and may be configured as an assembly of multiple modules.
[0038] The laser diode 12 and the LED 30 are examples of the laser light source and the LED light source of the present invention, respectively. The laser light source and the LED light source of the present invention may emit light of a color other than blue. In that case, the set values of λ1-λ4 are changed by a person skilled in the art according to the application situation.
[0039] In the light source device 10, the optical paths of the laser light LDb and the lights derived from the laser light LDb (primary fluorescence FL1 and secondary fluorescence FL2) extend in straight lines, but may be bent as appropriate depending on the application of the light source device 10.
[0040] The λ2 of the light source device 10 corresponds to the first wavelength of the present invention. In Fig. 3, λ2 is set to the wavelength of the minimum intensity of the synthetic spectrum, but the first wavelength of the present invention can also be set in the range of λ1<first wavelength<λ3.
[0041] λ1 of the light source device 10 corresponds to the maximum intensity wavelength of the LED light of the present invention. In the light source device 10, the LED light has only one maximum intensity wavelength, λ1, so λ1 is also the wavelength of the maximum light amount of the LED light.
[0042] The photodetector 24 of the light source device 10 corresponds to the optical sensor of the present invention. Each optical axis in the light source device 10 is also the optical path of the corresponding light.
[0043] In the light source device 10, in the optical element 36, the notch filter 38 and the dichroic mirror 40 are formed by film deposition on one and the other surfaces of a glass substrate 39. In the present invention, the transparent substrate on which the notch filter and the dichroic mirror are coated can also be a transparent substrate different from the glass substrate 39. [Explanation of symbols]
[0044] 10···light source device, 12···laser diode (laser light source), 18···phosphor, 24···photodetector, 30···LED (LED light source), 38···notch filter, 39···glass substrate (transparent substrate), 40···dichroic mirror, LDb···laser light, LEb···LED light, FL1···primary fluorescence, FL2···secondary fluorescence, FLc···reflected fluorescence.
Claims
1. a laser light source that emits laser light having a wavelength shorter than a first wavelength; a phosphor that is excited by the laser light and emits primary fluorescence having a wavelength longer than the first wavelength; a notch filter that emits secondary fluorescence obtained by attenuating the primary fluorescence from the phosphor in an attenuation wavelength range that includes a wavelength longer than the first wavelength; an LED light source that emits LED light having a wavelength shorter than the first wavelength; a dichroic mirror that outputs a combined light obtained by combining the secondary fluorescent light from the notch filter and the LED light from the LED light source; A light source device comprising:
2. The light source device according to claim 1 , wherein the notch filter separates the primary fluorescence into secondary fluorescence that is transmitted through the notch filter and reflected fluorescence that is reflected by the notch filter.
3. an optical sensor for detecting an amount of the primary fluorescent light in an optical path between the phosphor and the notch filter; The light source device according to claim 2 , wherein the notch filter is disposed in the optical path in a direction such that the reflected fluorescent light is reflected in a direction away from the optical sensor.
4. 2. The light source device according to claim 1, wherein the dichroic mirror causes the secondary fluorescent light incident from the notch filter at one surface to travel in a straight line and emits the secondary fluorescent light from the other surface, and reflects the LED light incident from the LED light source at the other surface in the same direction as the emission direction of the secondary fluorescent light.
5. 5. The light source device according to claim 1, wherein the notch filter and the dichroic mirror are formed on one surface and the other surface, respectively, of a same transparent substrate.
6. 5. The light source device according to claim 1, wherein in the combined light, a maximum light amount of the secondary fluorescent light is equal to a maximum light amount of the LED light.