LightMachinery光機(jī)公司

光機(jī)公司 (LightMachinery Inc.) 是位于加拿大首都渥太華的一家專業(yè)生產(chǎn)精密光學(xué)元件，光學(xué)加工設(shè)備和激光系統(tǒng)的公司。擅長于通過對(duì)現(xiàn)有加工工藝的改進(jìn)和提高，生產(chǎn)出精度要求非常嚴(yán)苛的光學(xué)產(chǎn)品，以滿足用戶的特殊需要。

光機(jī)公司的工作人員都是光學(xué)加工或激光領(lǐng)域的行家里手。幾乎每個(gè)雇員都具有在光學(xué)設(shè)計(jì)、大功率激光器、精密光學(xué)加工、激光系統(tǒng)、表面分析、光學(xué)鍍膜或機(jī)加工等領(lǐng)域中的某個(gè)領(lǐng)域的20年以上的工作經(jīng)驗(yàn)。已經(jīng)成功地為全球范圍內(nèi)的顧客提供高質(zhì)量的光學(xué)元件和激光設(shè)備，應(yīng)用范圍涵蓋空間科學(xué)、光通訊、半導(dǎo)體、高能激光、科學(xué)研究、非破壞性檢測、電子、制藥以及材料加工等多個(gè)領(lǐng)域。

作為一家高科技創(chuàng)新公司，光機(jī)公司現(xiàn)位于加拿大國家研究中心 (National Research council of Canada -- NRC)內(nèi)。主要辦公室和實(shí)驗(yàn)室位于研究中心的M-50 樓內(nèi)的“工業(yè)合作設(shè)施” (Industrial Partnership Facility -- IPF)里，而研發(fā)和光學(xué)加工則設(shè)在M-38 樓的國家測量標(biāo)準(zhǔn)所(Institute for National Measurement Standards)內(nèi)。通過依托于具有國際水平的科研院所，光機(jī)公司在光學(xué)加工、光學(xué)測量以及光學(xué)鍍膜等方面得到了加拿大國家研究中心的多方支持，這使得可以把主要精力和研究力量集中到新技術(shù)和新工藝的應(yīng)用上來。

通過利用加拿大國家測量標(biāo)準(zhǔn)所原有的光學(xué)加工設(shè)備和自己添置的設(shè)備，可以在各種光學(xué)材料上制備出光學(xué)平面、球面、柱面以及其它非球面，精度可以達(dá)到 1/100 激光波長的量級(jí)。

另一方面，激光應(yīng)用實(shí)驗(yàn)室裝備有 GSI Lumonics 的大功率二氧化碳激光器以及準(zhǔn)分子激光器。我們?cè)诩す鈶?yīng)用和激光加工設(shè)備的設(shè)計(jì)等方面的經(jīng)驗(yàn)使得我們可以在我們的實(shí)驗(yàn)室內(nèi)對(duì)工業(yè)或科研部門提供的樣品進(jìn)行激光處理，以找到設(shè)備配置和激光工作參數(shù)。光機(jī)公司的技術(shù)人員曾經(jīng)參與過大量的激光應(yīng)用方面的研發(fā)項(xiàng)目，包括：印刷電路板的打孔、啤酒瓶打標(biāo)、藥片打孔、膠囊打標(biāo)、紫外和紅外光譜儀以及激光等離子體超聲波的激發(fā)等。

Virtually Imaged Phase Arrays - VIPAs

VIPA is the acronym for “Virtually Imaged Phase Array”. A VIPA is a special case of Fabry-Perot etalon with three distinct coatings. This results in quite different performance compared to a regular etalon. One surface of a VIPA has an anti-reflection coated section adjacent to a high reflector. The opposite surface is coated with a partially transmitting mirror. Typically, the partial reflector has a reflectance >90%. Light is introduced into the VIPA at a line focus on the AR coated area. The two surfaces are parallel, and the VIPA is tilted so that the portion reflected from the partial reflector is fully incident on the high reflectance zone of the input surface.

So, a single input beam is converted to a series of parallel output beams of gradually decreasing intensity. These beams will constructively interfere at an angle that depends on the wavelength. Placing a lens between the VIPA and an array detector (CCD or similar) allows recording of a spectrum of the input light. Each subsequent beam has a precise increase in phase and fixed lateral displacement, hence “phase array”.

There are several parameters that define the performance of a VIPA. The first is its optical thickness. For a solid etalon this is OPD=2ntcos(θ), where n is the refractive index, t is the thickness, and θ is the angle from normal within the VIPA. From the optical thickness, the free spectral range (FSR) is approximately c/OPD. Analogous to a regular etalon, the angular dispersion of the VIPA output will repeat every time the input frequency (or wavelength) increases by 1 FSR.

The second important parameter is the reflectance of the output mirror. In principle, a higher reflectance mirror will increase the resolving power of the VIPA. Our experience is that a reflectivity of about 95% will result in a finesse of about 50. In other words, it will be possible to distinguish wavelengths separated by 1/50th of the FSR.

The third important parameter is the internal angle of the light travelling through the VIPA. Smaller angles increase the angular dispersion, but there are a couple of factors that put a lower limit on this angle. The first reflection from the partial reflector must be fully incident on the high reflector so a narrower transition between the antireflection coating and the high reflector enables a smaller angle. This transition is typically less than 100 μm. Secondly, the lateral offset of the reflected beam must be greater than the width of the input beam plus the width of the coating transition. Normally, this condition is optimized when the beam waist is located where the input beam first reflects from the partial reflector.

The VIPA coatings must be selected to match the wavelength range of interest, and the substrate material must also be transparent. The LightMachinery catalog VIPAs are all made of fused silica. Customized designs using calcium fluoride or silicon allow operation further into the infra-red.