CN203203714U - Absolute wavelength calibration instrument - Google Patents

Abstract

An absolute wavelength calibration instrument is composed of a calibration light source, a light source to be measured, a first optical fiber, a second optical fiber, an optical fiber coupler, a third optical fiber, small holes, a paraboloid high-reflectance mirror, an optical grating, an imaging lens, a linear photoelectric detector and a computer. According to the absolute wavelength calibration instrument of the utility model, the optical fiber coupler is adopted to input the calibration light source and the light source to be measured into a measuring system, and therefore, the problems existing in spatial alignment and optical path coaxality can be effectively solved, and the spatial size of the wavelength calibration instrument can be reduced; and the absolute wavelength of the light source to be measured can be obtained according to the distance between images of the light source to be measured and the calibration light source on the linear photoelectric detector, the focal length of the imaging lens and a grating constant distance. The absolute wavelength calibration instrument of the utility model can accurately and conveniently calibrate the wavelength of wavemeter or spectrometer.

Description

The absolute wavelength calibration instrument

Technical field

The utility model relates to a kind of absolute wavelength calibration instrument, mainly is applicable to wavemeter and spectrometer.

Background technology

Absolute wavelength is a basic optical parameter of laser.Have important effect in laser is used, for example imaging aberration, the raising design accuracy in order to revise projection objective in the litho machine need be known absolute optical maser wavelength.In laser spectrum tech, in order to improve the stability of laser output, need to measure in real time laser output wavelength, and come elements tune optical maser wavelengths such as tuning grating according to the drift value of output wavelength and target wavelength, thereby realize the stable control of optical maser wavelength.Therefore, to the demarcation of laser absolute wavelength with measure significant.

Earlier in technology, adopt a plurality of etalons and come the calibration laser wavelength with iterative algorithm, referring to document P.S.Bhatia, C.W.McCluskey, and J.W.Keto, " Calibration of a Computer-Controlled Precision Wavemeter for Use with Pulsed Lasers, " Appl.Opt.38,2486 (1999).Adopt iterative algorithm in this technology, and iterative algorithm is a kind of approximate data in essence, not only its precision is difficult to guarantee but also calculating process is time-consuming.In addition, the mode that this technology adopts space coupling only has a port when being coupled to regulation light source and light source to be measured in the measuring system, and two kinds of light sources need be connected to the purpose that just can realize in the system calibrating dividually.

Summary of the invention

The purpose of this utility model is to provide a kind of absolute wavelength calibration instrument, this absolute wavelength calibration instrument can be accurately, at a high speed, calibration laser absolute wavelength easily.

Technical solution of the present utility model is as follows:

A kind of absolute wavelength calibration instrument, it is characterized in that this absolute wavelength calibration instrument is made up of regulation light source, light source to be measured, first optical fiber, second optical fiber, fiber coupler, the 3rd optical fiber, aperture, parabolic high reflective mirror, grating, imaging len, linear photoconductor detector and computer, the position relation of each part mentioned above is as follows:

Regulation light source warp and light source to be measured are coupled to fiber coupler through first optical fiber and second optical fiber respectively, light beam arrives the aperture place through the 3rd Optical Fiber Transmission, the light beam of dispersing incides and incides grating after parabolic high reflective mirror expands and collimates, diffraction light focuses on the linear photoconductor detector through imaging len, and the output terminal of this linear photoconductor detector links to each other with the input end of described computer.

Described regulation light source is the known narrow linewidth light source of wavelength, and has wavelength stability preferably.

Described first optical fiber, second optical fiber and the 3rd optical fiber are radioresistance optical fiber, and have transmissivity preferably in wideer spectral range.

The curved surface of described parabolic high reflective mirror plating broadband highly reflecting films, guaranteeing all has higher reflectivity to the spectrum that regulation light source and light source to be measured comprise.

Described grating is reflective blazed grating, and it is inferior high that this grating has the order of diffraction, and dispersive power is big, the characteristics that spectrophotometric result is good.

The material of described imaging len is ultraviolet fused quartz or calcium fluoride crystal, to guarantee all have transmissivity preferably in wideer spectral range.

Described linear photoconductor detector is linear diode array or linear CCD.

Described computer comprises data collecting card and DAP, can the picture of linear photoconductor detector be read, record and data handle.Described data are handled namely and are carried out the data processing by following formula, and the absolute wavelength that obtains light source to be measured is λ _x:

${\mathrm{\λ}}_x={\mathrm{\λ}}_r+\mathrm{\Δ\λ}={\mathrm{\λ}}_r+\frac{2\mathrm{dh}\cos \mathrm{\α}}{\mathrm{kf}}(P_x-P_r)\·$

Wherein: λ _rBe regulation light source absolute wavelength, P _rAnd P _xBe respectively the location of pixels of regulation light source and light source to be measured imaging on linear photodetector, h is the unit picture element width, and d, α and k are respectively grating constant, blaze of grating angle and the order of diffraction time of grating, and f is the focal length of imaging len.

Technique effect of the present utility model is as follows:

The utility model is coupled to regulation light source and light source to be measured by the mode of fiber coupler the same fiber-optic output of fiber coupler, two light source repeated multiple times measuring system be need be connected to respectively when having solved the prior art spatial coupling, repeatability and difficulty that light path is aimed at reduced effectively.On the other hand, the utility model adopts to be measured because the method for the relative distance on the line detector that the deviation of the angle of diffraction of different wave length causes is directly calibrated wavelength, avoided iterative algorithm, have the high and advantage efficiently of calibration accuracy, can be used for the measurement of the centre wavelength of pulse laser and continuous laser simultaneously.

Description of drawings

Fig. 1 is the structured flowchart of the utility model absolute wavelength calibration instrument.

Embodiment

See also Fig. 1, Fig. 1 is the structured flowchart of the utility model absolute wavelength calibration instrument.As seen from the figure, the utility model absolute wavelength calibration instrument is made up of regulation light source 1, light source to be measured 2, first optical fiber 3, second optical fiber 4, fiber coupler 5, the 3rd optical fiber 6, aperture 7, parabolic high reflective mirror 8, grating 9, imaging len 10, linear photoconductor detector 11 and computer 12, and the position relation of each part mentioned above is as follows:

Regulation light source 1 links to each other with the input end of described fiber coupler 5 with second optical fiber 4 through first optical fiber 3 respectively with light source 2 to be measured, the light beam of the output terminal output of this fiber coupler 5 is transferred to aperture 7 places through the 3rd optical fiber 6, the light beam of dispersing incides parabolic high reflective mirror 8 and incide described grating 9 behind collimation, diffraction light focuses on the linear photoconductor detector 11 through imaging len 10, and the output terminal of this linear photoconductor detector 11 links to each other with the input end of described computer 12.

The location of pixels of hot spot imaging on linear photodetector 11 of 12 pairs of regulation light sources 1 of computer and light source to be measured 2 reads respectively and record, and data are analyzed and handled.

The known narrow linewidth light source of described regulation light source 1 wavelength, and have wavelength stability preferably.

Described first optical fiber 3, second optical fiber 4 and the 3rd optical fiber 6 are radioresistance optical fiber, have transmissivity preferably in wideer spectral range.

The curved surface of described parabolic high reflective mirror 8 plating broadband highly reflecting films, guaranteeing all has higher reflectivity to the spectrum that regulation light source 1 and light source to be measured 2 comprise.

Described grating 9 is reflective blazed grating, and it is inferior high that this grating has the order of diffraction, and dispersive power is big, the characteristics that spectrophotometric result is good.

The material of described imaging len 10 is ultraviolet fused quartz or calcium fluoride crystal, to guarantee all have transmissivity preferably in wideer spectral range.

Described linear photoconductor detector 11 is linear diode array or linear CCD.

Described computer 12 comprises data collecting card and DAP, can read linear photoconductor detector 11, record and data analysis.

Regulation light source 1 and light source to be measured 2 are coupled to fiber coupler 5 through first optical fiber 3 and second optical fiber 4 respectively, be transferred to aperture 7 places through the 3rd optical fiber 6, the light beam of dispersing incides and incides grating 9 after parabolic high reflective mirror 8 expands and collimates, when incident beam and grating 9 were in Littrow (Littrow) structure, grating equation can be written as

2dsin α=k λ, [1] wherein: d is grating constant, and α is blaze of grating angle, and k is the order of diffraction time, and is time identical in order to guarantee optical maser wavelength order of diffraction when grating 9 diffraction, requires the optical maser wavelength of regulation light source 1 and light source to be measured 2 close.

Grating equation [1] differential is had:

2dcosαΔα＝kΔλ, [2]

When being f as the focal length of imaging len 10, the relative distance of the hot spot of different wave length on linear photodetector 11 is:

ΔL＝fΔα. [3]

Regulation light source 1 λ _rWith light source 2 λ to be measured _xThe location of pixels of imaging is respectively P on linear photodetector 11 _rAnd P _x, be h as the unit picture element width, then the distance of the hot spot of two wavelength on imaging surface is

ΔL＝h(P _x-P _r). [4]

Can obtain the diffraction angular difference of two wavelength correspondences according to formula [3] and formula [4]

$\mathrm{\Δ\α}=\frac{h}{f}(P_x-P_r).---\left[5\right]$

Formula [5] substitution formula [2] can be obtained wavelength to be measured and the wavelength difference of calibration between the wavelength,

$\mathrm{\Δ\λ}=\frac{2\mathrm{dh}\cos \mathrm{\α}}{\mathrm{kf}}(P_x-P_r).---\left[6\right]$

Then the absolute optical maser wavelength of light source 2 to be measured is

${\mathrm{\λ}}_x={\mathrm{\λ}}_r+\mathrm{\Δ\λ}={\mathrm{\λ}}_r+\frac{2\mathrm{dh}\cos \mathrm{\α}}{\mathrm{kf}}(P_x-P_r).---\left[7\right]$

Therefore, the image-forming range on linear photodetector 11 according to regulation light source 1 and light source to be measured 2 can realize treating the absolute wavelength calibration in photometry source 2.

Claims (7)

1. absolute wavelength calibration instrument, it is characterized in that this prover is by regulation light source (1), light source to be measured (2), first optical fiber (3), second optical fiber (4), fiber coupler (5), the 3rd optical fiber (6), aperture (7), parabolic high reflective mirror (8), grating (9), imaging len (10), linear photoconductor detector (11) and computer (12) are formed, the position relation of each part mentioned above is as follows: described regulation light source (1) links to each other with the input end of second optical fiber (4) with described fiber coupler (5) through first optical fiber (3) respectively with light source to be measured (2), the coupled light beam of the output of this fiber coupler (5) is transferred to described aperture (7) through the 3rd optical fiber (6) and locates, the light beam of being dispersed by this aperture (7) incides described grating (9) after described parabolic high reflection mirror (8) expands and collimates, described regulation light source (1) and light source to be measured (2) are imaged on the described linear photoconductor detector (11) by described imaging len (10) through the diffraction of this grating (9), and the output terminal of this linear photoconductor detector (11) links to each other with the input end of described computer (12).

2. absolute wavelength calibration instrument according to claim 1 is characterized in that described regulation light source (1) is the known narrow linewidth light source of wavelength.

3. wavelength calibration instrument according to claim 1 is characterized in that described first optical fiber (3), second optical fiber (4) and the 3rd optical fiber (6) are radioresistance optical fiber.

4. absolute wavelength calibration instrument according to claim 1 is characterized in that the curved surface of described parabolic high reflective mirror (8) plates the broadband highly reflecting films.

5. absolute wavelength calibration instrument according to claim 1 is characterized in that described grating (9) is reflective blazed grating.

6. absolute wavelength calibration instrument according to claim 1 is characterized in that described imaging len (10) made by ultraviolet fused quartz or calcium fluoride crystal.

7. absolute wavelength calibration instrument according to claim 1 is characterized in that described linear photoconductor detector (11) is linear diode array or linear CCD.

Images