CN200986650Y - Device for testing performance of optical low-pass filter - Google Patents

Abstract

The utility model discloses a testing device and aims to provide a device to test the performance of an optical lowpass. The device comprises a light source. A fender with little holes, an optical imaging system A, an image transferring system, an optical imaging system B and a image sensor are equipped in sequence on a light path of the light source. A computer system is connected to the image sensor and used to process the electrical signal transmitted by the image sensor into the image data result. The placement position of the lowpass to be tested is equipped at the light path between the image transferring system and the optical imaging system B. The image transferring system is a right-angle prism. The optical imaging system A and the optical imaging system B each comprise at least a microscope. Compared with the prior are, the device to test the performance of an optical lowpass provided by the utility model is rapider and exacter. Moreover, more lowpasses can be tested each time.

Description

Apparatus for testing performance of optical low pass filter

Technical field

The utility model relates to a kind of proving installation, particularly the device of testing performance of optical low pass filter.

Background technology

Digital camera and Digital Video adopt the solid imaging element such as CCD (charge-coupled image sensor), the high spatial frequency (nyquist frequency) of photo electric imaging system is 1/2 of its spatial sampling frequency, be higher than nyquist frequency if be sampled the frequency spectrum high fdrequency component of image, then the HFS on the image will be overlapped with fundamental frequency and be caused the spectral aliasing of image, and the process of reconstruction of image can not be eliminated aliasing, thereby meeting and subject form Moire effect, for this reason, an optical low-pass filter (optical low-pass filter) generally is provided between camera and imaging surface, thereby effectively suppresses high spatial frequency component in the image that on imaging surface, forms.

Now, along with popularizing fast of digital camera and Digital Video, the demand of optical low-pass filter sharply increases, market outlook are good, the optics processing factory that remarkable in economical benefits, domestic minority can be produced optical low-pass filter has obtained the approval of international digital camera manufacturer on process technology.The detection method of traditional optical low-pass filter mainly is that the thickness to every quartz plate is measured in process, and the method for behind glue molding, measuring again, owing to there is not special-purpose checkout equipment, cause that measuring method is loaded down with trivial details, precision is low, can not satisfy the demand of market a large amount of optical low-pass filters.Therefore, develop a kind of can be fast, in batches, accurately the instrument of detection optical low-pass filter performance becomes problem demanding prompt solution.

Summary of the invention

The purpose of this utility model is to overcome deficiency of the prior art, provide a kind of can be fast, in batches, the accurate device of detection optical low-pass filter performance.In order to solve the problems of the technologies described above, the utility model is achieved through the following technical solutions:

The utility model provides a kind of apparatus for testing performance of optical low pass filter, comprise light source, on the light path of light source, set gradually narrow meshed baffle plate, optical imaging system A, relay system, optical imaging system B and imageing sensor, a computer system is connected in imageing sensor, is used for the electric signal that imageing sensor transmits is processed into the view data result; Tested optical low-pass filter putting position is located on the light path between relay system and the optical imaging system B;

Described relay system is a right-angle prism; Described optical imaging system A and optical imaging system B respectively comprise at least one microcobjective.

As a kind of improvement, described graphical sensory device comprises a CMOS or ccd image acquisition chip.

As a kind of improvement, described computer system is connected with imageing sensor by the usb signal line.

As a kind of improvement, described computer system comprises a display, is used to receive and shows the view data result of machine system handles as calculated.

As a kind of improvement, described light source is a pointolite.

Compared with prior art, the beneficial effects of the utility model are:

The device of the detection optical low-pass filter performance that the utility model provides with respect to prior art more fast, in batches, accurately.

Description of drawings

Fig. 1 is the structural representation of proving installation among the embodiment 1;

Fig. 2 is tested optical low-pass filter glazed thread route synoptic diagram.

Embodiment

Further the utility model is described by specific embodiment 1 below in conjunction with accompanying drawing 1,2.

Apparatus for testing performance of optical low pass filter among the embodiment, comprise light source 1, on the light path of light source, set gradually narrow meshed baffle plate 2, optical imaging system A3, relay system 4, optical imaging system B5 and imageing sensor 6, tested optical low-pass filter 7 putting positions are located on the light path between relay system 4 and the optical imaging system B5.

Narrow meshed baffle plate 2 is used to form pointolite.Optical imaging system A3 is a microcobjective (also can be one group of microcobjective).Relay system 4 is the employing right-angle prism, and it places requirement can transfer glancing incidence light to vertical outgoing, changes the direction of light path, and with the image formation by rays of the pointolite of optical imaging system A3 transmission on optical low-pass filter to be measured 7 surfaces.Optical imaging system B5 is a microcobjective (also can be one group of microcobjective), is used for passing through the image formation by rays of optical low-pass filter 7 to be measured in imageing sensor 6.Imageing sensor 6 comprises a cmos image acquisition chip (also can be the ccd image acquisition chip), is used to accept the optical signalling by optical imaging system B5, and converts electric signal to.A computer system is connected in imageing sensor 6 by the usb signal line, is used for the electric signal that imageing sensor 6 transmits is processed into the view data result.Computer system also comprises a display, is used to receive and shows the view data result of machine system handles as calculated.

The principle of work of this proving installation is: the light that light source 1 sends forms pointolite through aperture, be imaged on the surface of optical low-pass filter 7 after relay system 4 refractions by optical imaging system A3, owing to see through optical low-pass filter 7, the HFS of image is suppressed, low frequency part is imaged on the cmos image acquisition chip of imageing sensor 6 by optical imaging system B5, picture signal is input to computer system by USB interface, calculate the structural parameters and the optical transfer function thereof of optical low-pass filter by software kit, and the view data of handling be the results are shown on the display.

In this proving installation:

Light source 1 should have following characteristics: (1) can provide stable luminous energy, luminous power with require image to be complementary; (2) adopted incoherent light source (and not requiring it to be incoherent light source); (3) life-span is long; (4) feed circuit are simply stablized.

The hole diameter of baffle plate 2 requires moderate, if too big, then image is difficult to differentiate, can not be too little, otherwise the obvious diffraction pattern appears easily, and being difficult to calculate, hole diameter is 20 μ m in the present embodiment, when the light source light irradiation, constitutes a pointolite.Also can directly adopt pointolite.

Optical imaging system A3 adopts common microcobjective, and requirement can be with the surface of pinhole imaging system at optical low-pass filter 7, and the aperture of its enlargement ratio and aperture and the pixel size of electronic eyepiece will be complementary, 10 times enlargement ratio in the present embodiment.

Optical imaging system B2 also adopts common microcobjective, require can be by optical low-pass filter 7 photoimaging at imageing sensor 6, and require that the spot distance of the separation that collects divides open better and better, the enlargement ratio of 60 times of employings in the present embodiment.

Cmos image acquisition chip physical dimension in the present embodiment is 1/2 inch, effectively pixel unit 1632 * 1224.The cmos image acquisition chip that present embodiment adopts is produced by motorola inc.

The utility model realizes that testing principle is as follows:

The ultimate principle of optical low-pass filter is to utilize birefringece crystal (birefringece crystal is few, the simple optical low-pass filter of a kind of use occasion).Behind imaging light beam process crystal, the information that has same target image is divided into o light and e light, as shown in Figure 2, when light impinges perpendicularly on birefringece crystal, supposes incident ray and optical axis included angle θ; n _o, n _eRefractive index for ordinary light and non-ordinary light.T is a crystal thickness.During outgoing, o light with the distance that e light separates is so

$a=T\frac{(n_o^2-n_e^2)\mathrm{tg\&theta;}}{n_o^2{\mathrm{<figure-callout\; id="2"\; label="tg"\; filenames="Y20062014030000071.png"\; state="\{\{state\}\}">tg</figure-callout>}}^2\mathrm{\&theta;}+{\mathrm{<figure-callout\; id="2"\; label="n\; e"\; filenames="Y20062014030000071.png"\; state="\{\{state\}\}">n</figure-callout>}}_e^{}}$

Then the luminous point distance of separating is also just different for the thickness that changes birefringece crystal, and the birefringece crystal of monolithic is equivalent to spatial comb filter

$h\left(x\right)=\frac{1}{2}[\mathrm{\&delta;}\left(x\right)+\mathrm{\&delta;}(x-a)]$

Its transport function is: H (s)=cos (π as) exp (j π as)

Imageing sensor is sent to computer system by the usb signal line with electric signal, calculate a little spacing α with point by computer system, thereby calculate the thickness T of corresponding birefringece crystal, can calculate the optical transfer function of corresponding birefringece crystal by this transport function, in like manner, the multiple-piece optical low-pass filter also can obtain its corresponding transport function and optical transfer function as method.

At last, it is also to be noted that what more than enumerate only is specific embodiment of the utility model.Obviously, the utility model is not limited to above examples of implementation, and many distortion can also be arranged.All distortion that those of ordinary skill in the art can directly derive or associate from the disclosed content of the utility model all should be thought protection domain of the present utility model.

Claims (5)

1, a kind of apparatus for testing performance of optical low pass filter, comprise light source, it is characterized in that, on the light path of light source, set gradually narrow meshed baffle plate, optical imaging system A, relay system, optical imaging system B and imageing sensor, a computer system is connected in imageing sensor, is used for the electric signal that imageing sensor transmits is processed into the view data result; Tested optical low-pass filter putting position is located on the light path between relay system and the optical imaging system B;

Described relay system is a right-angle prism; Described optical imaging system A and optical imaging system B respectively comprise at least one microcobjective.

2, apparatus for testing performance of optical low pass filter according to claim 1 is characterized in that, described graphical sensory device comprises a CMOS or ccd image acquisition chip.

3, apparatus for testing performance of optical low pass filter according to claim 1 is characterized in that, described computer system is connected with imageing sensor by the usb signal line.

4, apparatus for testing performance of optical low pass filter according to claim 1 is characterized in that, described computer system comprises a display, is used to receive and shows the view data result of machine system handles as calculated.

5, apparatus for testing performance of optical low pass filter according to claim 1 is characterized in that, described light source is a pointolite.

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