TWM625148U - Image collimator for measuring optical lens focal length - Google Patents

Abstract

The new model mainly discloses an image collimator for measuring the focal length of an optical lens, which comprises: a collimating light source, a light input unit, a scribe plate, a collimator, a light output unit, an optical lens, A light sensing device, and an electronic device. When using the image collimator of the present invention to measure the focal length of a lens to be tested, the lens to be tested is positioned between the light output unit and the optical lens. Next, the collimated light source emits a collimated light, and the light input unit converts the collimated light into a detection light to irradiate the scribe plate, so that the collimated light pipe correspondingly outputs a parallel beam, which is projected by the light output unit In the lens to be tested, light sensing is finally performed by the light sensing device to obtain an image. When a position of the lens to be tested is adjusted forward and backward to make the image clear, the electronic device calculates the focal length of the lens to be tested according to the position and the principle of geometric optics.

Description

Image Collimator for Measuring Optical Lens Focal Length

The present invention relates to the technical field of parameter measurement of optical elements, in particular to an image-type collimator for measuring the focal length of an optical lens.

As is known, it is mentioned that light travels in a straight line through a medium, so optical phenomena of transmission, refraction and/or reflection occur when encountering different media. It should be known that a convex lens focuses light on a focal point. On the other hand, a concave lens is also called a diverging lens, and its focal length refers to the distance from the focal point to the center of the lens. In more detail, the lens of the camera is usually a lens group composed of one or more pieces of optical glass, generally composed of a concave lens, a convex lens, or a combination thereof.

Therefore, measuring the focal length of the lens is of great significance for studying the performance of the optical lens. Conventionally, a narrow beam of parallel light emitted by a laser light source is used, and then the narrow beam of parallel light is expanded into a wide beam of parallel light by a beam expander, so that the wide beam of parallel light is vertically irradiated on a lens under test. Finally, the focal length of the lens to be tested (ie, a convex lens or a concave lens) can be determined according to the properties of light and the principles of geometric optics.

It should be understood that the conventional method for measuring the focal length of a lens is an easy-to-operate method for measuring the focal length of a lens. However, the conventional method for measuring the focal length of a lens is not suitable for directly measuring the focal length of an optical lens (ie, a lens group). The reason is that the divergence effect of the concave lens included in the optical lens will make the laser light spot larger after refraction, so that it is difficult to determine the position of the light spot, resulting in a large error. Second, the diameter of the laser beam expansion is a finite size (usually less than 70mm). Furthermore, the accuracy of measuring the focal length by the object distance image distance method and the autocollimation method is limited by the subjective observation and judgment ability of the human eye and aberrations.

As can be seen from the above description, the application of the conventional method for measuring the focal length of a lens to the measurement of the focal length of an optical lens shows that there is a need for improvement. In view of this, the creative person in this case made great efforts to research and create, and finally developed a new type of image collimator for measuring the focal length of an optical lens.

The present invention mainly provides an image collimator for measuring the focal length of an optical lens, which includes: a collimating light source, a light input unit, a scribe plate, a collimator, a light output unit, and an optical lens , a light sensing device, and an electronic device. When using the image collimator of the present invention to measure the focal length of a lens to be tested, the lens to be tested is positioned between the light output unit and the optical lens. Next, the collimated light source emits a collimated light, and the light input unit converts the collimated light into a detection light to irradiate the scribe plate, so that the collimated light pipe correspondingly outputs a parallel beam, which is projected by the light output unit In the lens to be tested, light sensing is finally performed by the light sensing device to obtain an image. When a position of the lens to be tested is adjusted forward and backward to make the image clear, the electronic device calculates the focal length of the lens to be tested according to the position and the principle of geometric optics.

In order to achieve the above object, the present invention proposes an embodiment of the image-type collimator for measuring the focal length of an optical lens, which includes: a collimated light source; A light input unit, facing the collimated light source and coaxial with the collimated light source; a parallel light pipe, connected to the light input unit with a light input side, and a scribe plate is arranged on the light input side and the light input unit; a light output unit connected to a light output side of the collimator; an optical lens facing the light output unit and coaxial with the light output unit; a light sensing device , connecting the optical lens; and an electronic device, electrically connecting the light sensing device and the collimating light source; wherein, when a focal length measurement procedure is performed on a lens to be tested, the lens to be tested is located in the light output unit between the optical lens and the same optical axis as the optical lens; wherein, the electronic device controls the collimated light source to emit a collimated light, and the light input unit converts the collimated light into a detection light to illuminate the scribing plate , so that a light to be inspected passing through the scribing plate enters the collimated light pipe through the light input side to generate a parallel beam; wherein, the parallel beam is projected on the lens to be inspected by the light output unit, and further passes through the The optical lens is finally photo-sensed by the photo-sensing device to obtain an image; wherein, when a position of the lens to be tested is adjusted forward and backward to make the image clear, the electronic device determines the position according to the position And the principle of geometric optics calculates the focal length of the lens to be tested.

In a feasible embodiment, the image-type collimator for measuring the focal length of an optical lens according to the present invention further includes a distance measuring device, which is connected to a lens clamping mechanism for carrying the lens to be measured, for When the lens to be tested moves forward and backward, a moving distance of the lens to be tested is detected.

In one embodiment, the distance measuring device includes at least one distance sensor, and the distance sensor is selected from the group consisting of an ultrasonic distance sensor, an infrared distance sensor and a radar distance sensor any of the groups.

In one embodiment, the collimated light source is a quartz tungsten halogen lamp, and a light wavelength bandwidth of the collimated light is between 400 nm and 2200 nm.

In one embodiment, the light output unit is an objective lens.

In one embodiment, the light input unit includes: a lens; a filter, coaxial with the lens; wherein, the lens is used for condensing the collimated light to the filter, and the filter The light sheet filters the collimated light into a green light; a scattering sheet, coaxial with the light filter, is used for scattering the green light into a detection light to illuminate the scribe plate.

In one embodiment, the scoring plate includes a sapphire glass and a reticle including a resolution scale target scored on the sapphire glass. And, the diffuser is a frosted frosted glass.

In one embodiment, the light-sensing device is a CMOS light-sensing device that specifically senses the green light.

In one embodiment, the electronic device is any one selected from the group consisting of a desktop computer, an all-in-one computer, a notebook computer, a tablet computer, and a smart phone By.

1: Image collimator used to measure the focal length of the optical lens

10: Collimated light source

1in: Optical input unit

1i1: Lens

1i2: filter

1i3: Diffuser

1out: light output unit

1P: Scoring board

11: collimator light pipe

12: Optical lens

13: Light sensing device

14: Electronics

15: Ranging device

2: Lens to be tested

P1, P2, P3: Crosshair pattern images of the scribing plate

C1, C2, C3, C4: Lens Products

1 is a block diagram of a new type of image collimator for measuring the focal length of an optical lens; FIG. 2A is a first perspective view of the new type of image collimator for measuring the focal length of an optical lens; FIG. 2B is a A second perspective view of a new type of image collimator for measuring the focal length of an optical lens; Fig. 3 shows the collimating light source, light input unit, scoring plate, collimator light pipe, light output unit, optical lens, And the optical structure diagram of the light sensing device; FIG. 4 is an image diagram of the cross reticle pattern of the scoring plate; FIG. 5 is an image diagram of the cross line pattern of two scoring plates; FIG. 6 is the image of the first lens product 7 is an image diagram of a second lens product; FIG. 8 is an image diagram of a third lens product; and FIG. 9 is an image diagram of a fourth lens product.

In order to more clearly describe an image-type collimator for measuring the focal length of an optical lens proposed by the present invention, a preferred embodiment of the present invention will be described in detail below with reference to the drawings.

Please refer to FIG. 1 , which shows a block diagram of an image-type collimator for measuring the focal length of an optical lens according to the present invention. 2A and 2B show the first and second perspective views of the image-type collimator for measuring the focal length of an optical lens according to the present invention. Figure 1, Figure 2A and Figure 2 As shown in 2B, the image collimator 1 of the present invention for measuring the focal length of an optical lens includes: a collimating light source 10, a light input unit 1in, a scribe plate 1P, a collimator light pipe 11, and a light output unit 1out, an optical lens 12 , a light sensing device 13 , a distance measuring device 15 , and an electronic device 14 . According to the design of the present invention, the light input unit 1in is configured to face the collimated light source 10 and is coaxial with the collimated light source 10 . In addition, a light input side and a light output side of the collimator 11 are respectively connected to the light input unit 1in and the light output unit 1out, and a scribe plate 1P is arranged between the light input side and the light input unit 1in between. In more detail, the optical lens 12 faces the light output unit 1out, and is coaxial with the light output unit 1out. Moreover, the light sensing device 13 is connected to the optical lens 12 , and the electronic device 14 is electrically connected to the light sensing device 13 and the collimating light source 10 .

FIG. 3 shows an optical structure diagram of the collimated light source 10 , the light input unit 1in , the scoring plate 1P , the collimator light pipe 11 , the light output unit 1out , the optical lens 12 , and the light sensing device 13 shown in FIG. 2A . According to the design of the present invention, when a focal length measurement is performed on a lens to be tested 2 , the lens to be tested 2 is located between the light output unit 1out and the optical lens 12 and is coaxial with the optical lens 12 . Next, the electronic device 14 controls the collimating light source 10 to emit a collimated light, and the light input unit 1in converts the collimated light into a detection light to irradiate the reticle 1P, thereby passing through a pending inspection of the reticle 1P Light enters the collimator light pipe 11 through the light input side to generate a parallel beam.

In one embodiment, the collimated light source 10 is a quartz tungsten halogen lamp, and a light wavelength bandwidth of the collimated light is between 400 nm and 2200 nm. And, the light input unit 1in includes: a lens 1i1, a filter 1i2 and a diffusion sheet 1i3. The filter 1i2 is coaxial with the lens 1i1, so that the lens 1i1 condenses the collimated light to The filter 1i2, and then the collimated light is filtered into a green light by the filter 1i2. As shown in FIG. 2A , FIG. 2B and FIG. 3 , the diffuser 1i3 (eg: frosted frosted glass) is coaxial with the filter 1i2 for scattering the green light into the detection light to illuminate the scribe plate 1P. In other words, the detection light is a uniform green plane light.

Next, the parallel light beam is projected on the lens to be measured 2 by the light output unit 1out, and further passes through the optical lens 12, and finally is subjected to light sensing by the light sensing device 13 to obtain an image. In one embodiment, the light output unit 1out is an objective lens, and the scribing plate 1P includes: a sapphire glass and a reticle including a resolution scale target scribed on the sapphire glass. Therefore, it can be understood that the image is the reticle pattern image P1 of the reticle as shown in FIG. 4 .

In order to obtain a clear reticle pattern image of the scribing plate, a position of the lens 2 to be tested can be adjusted forward and backward to make the image clear, the electronic device 14 is based on the position and the principle of geometric optics. Calculate the focal length of the lens 2 to be tested. It is worth noting that, in the present invention, a distance measuring device 15 is coupled to the electronic device 14 and connected to a lens clamping mechanism for carrying the lens 2 to be measured, so as to move forward and backward of the lens to be measured 2 At this time, a moving distance of the lens 2 to be tested is detected. In a feasible embodiment, the distance measuring device 15 includes at least one distance sensor, and the distance sensor may be an ultrasonic distance sensor, an infrared distance sensor or a radar distance sensor. On the other hand, the electronic device 14 can be a desktop computer, an all-in-one computer, a notebook computer, a tablet computer, or a smart phone.

If the distance between a pair of reticle on the focal plane of the objective lens on the light output side of the collimator 11 (ie, the light output unit 1out) is y. Then, theoretically, the reticle would be projected (ie, imaged) at infinity by the objective lens of the collimator 11 (ie, the light output unit 1out). However, as shown in FIGS. 2A and 3 , the lens under test 2 is disposed between the light output unit 1out and the optical lens 12 , so the parallel light beam is projected on the lens under test 2 by the light output unit 1out, And further through the optical lens 12 . Therefore, on the focal plane of the lens 2 to be tested, the interval distance between a pair of scribed lines of the crosshair can be obtained as y'. Therefore, based on the principle of geometric optics, the following formula (1) can be used to calculate the focal length of the lens to be tested 2:

In the above formula (1), the focal length of the objective lens of the collimator 11 is f, and the focal length of the lens 2 to be measured is f'. It should be understood that f and y are known values, so as long as a position of the lens to be tested 2 is adjusted forward and backward to make the image clear, the value of y' can be known, and finally calculated by formula (1) The value of f' is obtained, so as to complete the focal length measurement of the lens 2 to be tested.

It is added that adding an optical lens 12 with a known focal length (for example: 16mm) to the system is beneficial to adjust a position of the lens 2 to be tested before and after to make the image clear. As shown in FIG. 2A and FIG. 2B , if an optical lens 12 with a known focal length is used, a lens distance between the optical lens 12 and the lens to be measured 2 and a known lens distance can be input on the man-machine interface of the electronic device 14 . The focal length of the optical lens 12. Next, the procedure for measuring the focal length of the lens 2 to be tested as described above is started. Finally, the length of the left and right sides of the image including the reticle 1P displayed on the screen of the electronic device 14 is 750 pixels, and the focal length of the lens 2 to be measured (eg, 56.6 mm) is calculated.

Since the reticle 1P target is composed of black lines, after obtaining the image of the reticle pattern of the reticle, the image can be further contrasted locally. change. Local contrast enhancement is different from general contrast enhancement. If you directly contrast and enhance the entire image, a brighter image will be obtained, and the details of the black line of the cross target will be ignored. On the contrary, local contrast enhancement can improve this problem, by detecting the details of the image through the edge, and only digitally filtering the area of interest. Compared with the background signal, these details tend to be high frequency signals. Using a digital high-pass filter can effectively produce clear lines. FIG. 5 shows images of crosshair patterns of two scribing plates 1P. According to (a) the reticle pattern image P2 of the scribing plate (before local contrast enhancement) and (b) the reticle pattern image P3 of the scribing plate (after local contrast enhancement), it can be clearly seen that after After local contrast enhancement, clear black thin lines can be seen, which is very helpful for the determination of pixel positions.

Experimental example

In the experimental example, the focal length of four different lens products was measured by using an image-type collimator 1 of the present invention for measuring the focal length of an optical lens. 6 , 7 , 8 and 9 show the image diagrams of the first lens product C1 , the second lens product C2 , the third lens product C3 and the fourth lens product C4 . After completing the focal length measurement procedure of each lens product, four images of the reticle 1P including the cross reticle were obtained, and the lengths of the left and right sides were 213 pixels, 464 pixels, 975 pixels, and 1333 pixels, respectively. Further, the above formula (1) is used to calculate the focal lengths of the four lens products, which are 16.1mm, 35.0mm, 74.6mm, and 100.5mm, respectively. The results show that the new image-type collimator 1 has good accuracy in measuring optical lenses.

In this way, the above has completely and clearly described a novel image-type collimator for measuring the focal length of an optical lens. However, it must be emphasized that the aforementioned The one shown is a preferred embodiment, and any partial changes or modifications originating from the technical ideas of the present case and easily inferred by those skilled in the art are within the scope of the patent right of the present case.

1: Image collimator used to measure the focal length of the optical lens

10: Collimated light source

1in: Optical input unit

1out: light output unit

11: collimator light pipe

12: Optical lens

13: Light sensing device

14: Electronics

15: Ranging device

2: Lens to be tested

Claims (10)

An image-type collimator for measuring the focal length of an optical lens, comprising: a collimated light source; a light input unit facing the collimated light source and having the same optical axis as the collimated light source; A light input side is connected to the light input unit, and a scribe plate is arranged between the light input side and the light input unit; a light output unit is connected to a light output side of the collimator; an optical lens, surface the light output unit and the same optical axis as the light output unit; a light sensing device connected to the optical lens; and an electronic device electrically connected to the light sensing device and the collimating light source; wherein, for a When the lens to be tested performs a focal length measurement procedure, the lens to be tested is located between the light output unit and the optical lens, and is coaxial with the optical lens; wherein, the electronic device controls the collimating light source to emit a collimated light source. Straight light, the light input unit converts the collimated light into a detection light and irradiates the scribe plate, so that a light to be inspected passing through the scribe plate enters the collimator light pipe through the light input side to generate a parallel beam; wherein , the parallel light beam is projected on the lens to be tested by the light output unit, and further passes through the optical lens, and finally is subjected to light sensing by the light sensing device to obtain an image; wherein, the front and rear adjustment of the test lens When a position of the lens makes the image clear, the electronic device calculates the focal length of the lens to be tested according to the position and the principle of geometric optics. The image collimator for measuring the focal length of an optical lens as claimed in claim 1, further comprising a distance measuring device coupled to the electronic device and connected to a lens holder for carrying the lens to be measured The mechanism is used to detect a moving distance of the lens to be tested when the lens to be tested moves forward and backward. The image-type collimator for measuring the focal length of an optical lens according to claim 2, wherein the distance measuring device comprises at least one distance sensor, and the distance sensor is selected from ultrasonic distance sensors. Any one of the group consisting of a sensor, an infrared distance sensor, and a radar distance sensor. The image collimator for measuring the focal length of an optical lens according to claim 1, wherein the collimating light source is a quartz tungsten halogen lamp, and a light wavelength bandwidth of the collimating light is between 400nm and 2200nm between. The image collimator for measuring the focal length of an optical lens according to claim 1, wherein the light output unit is an objective lens. The image collimator for measuring the focal length of an optical lens according to claim 1, wherein the light input unit comprises: a lens; a filter, coaxial with the lens; wherein the lens is used to The collimated light is condensed to the filter, and the collimated light is filtered into a green light by the filter; a diffuser, coaxial with the filter, is used for scattering the green light into a green light. The detection light is used to illuminate the reticle. The image-type collimator for measuring the focal length of an optical lens as claimed in claim 1, wherein the scoring plate comprises: a sapphire glass and a cross reticle including a resolution scale target scored on the sapphire glass . The image collimator for measuring the focal length of an optical lens according to claim 6, wherein the diffusing sheet is a frosted frosted glass. The image collimator for measuring the focal length of an optical lens as claimed in claim 6, wherein the light sensing device is a CMOS light sensing device specially sensing the green light. The image collimator for measuring the focal length of an optical lens according to claim 1, wherein the electronic device is selected from a desktop computer, an All-in-one computer, a notebook computer, Any of the group consisting of tablets, and smartphones.

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