Gelişen teknolojilere paralel olarak imal edilen ürünlerin boyutlarının küçülmesi ve yüzey hassasiyetlerinin artıp parçaların daha kırılgan yapıya sahip olmaları, araştırmacıları bilinen standart temaslı ölçme aletlerinin dışında hasarsız ve hızlı yeni ölçme tekniklerini aramaya yönlendirmiştir. Optik ölçme teknikleri de hasarsız ölçme kapasiteleri nedeniyle 1960’lardan başlayarak günümüze kadar büyük bir hızla gelişmiş ve günümüzde hiç tartışmasız mikro teknolojiden bio-teknolojiye birçok alanda temaslı ölçme cihazlarının yerini almıştır. Konfokal mikroskop ise 1960 yılında M. Minsky tarafından geliştirilmiş ve standart mikroskoplara oranla daha hassas ve detaylı ölçme kapasitesi sunması nedeniyle diğer optik ölçme metodları arasından hızla sıyrılmıştır. 1990’larda, Xiao, Corle, ve Kino’nun çalışmaları ile gerçek zamanlı görüntüleme özelliği kazandırılmış ve konfokal mikroskop endüstrinin vazgeçilmez temel optik ölçme cihazı haline gelmiştir. Bu çalışma kapsamında mikro ayna dizinli (DMD™) optik anahtarların yardımı ile yeni bir tip konfokal mikroskop geliştirilmiştir. Geliştirilen bu yeni ölçme sisteminde mikro ayna dizini ölçülecek yüzey üzerine 1-1 görüntülenmiş ve bu sayede yüzlerce noktanın aynı anda video frekansında ölçülmesi gerçekleştirilmiştir. 3D yüzeyin elde edilmesi çeşitli yüksekliklerde elde edilen 2D bilgilerinin üst üste getirilmesi ile oluşturulmuştur. Bu çalışma sırasında mikroskobun optik tasarımı ve elde edilen optik sistemin geliştirilme aşamaları bütün detayları ile verilmiş, geliştirilen deneysel düzenek detayları ile tartışılmıştır. Ölçümler sırasında 50 defa büyütmeli ve 0.95 NA’ya sahip mikroskop objektifi ile yapılan ölçümlerde yatay çözünürlük değeri 1.5 μm olarak bulunmuştur. Sonuçların bu kadar iyi olmasında kullanılan mikro ayna dizinli elemanın önemli bir rolü olmuştur. Geliştirilen sistemin ölçme kapasitesi farklı ölçme standartları kullanılarak örneklendirilmiştir.

In this paper a new method for non-contact scanning of engineering surfaces will be presented. Similar to the classical confocal microscope principal but without using real physical pinholes a new method that uses Digital Micromirror Device1 (DMDTM) as virtual illumination pinhole and selective CCD camera as virtual detection is developed. With this study, this new, flexible and highly accurate a micromirror- based system will be introduced. The concept concerning system layout and system performance together with the measurement results will be presented. Confocal microscopy was first described by M. Minsky in 1957 and in last couple decades it becomes one of the most powerful tool for 3D characterization of complex engineering surfaces. In reflection mode confocal microscopy applications a point illumination source is imaged onto object by using a microscope objective (first focus point). This focusing point on object results with maximum intensity on a detector by passing through the detector pinhole (second focus point) where the lights from defocused neighborhoods object regions are strongly suppressed by the pinhole. In other words, the detector signal that is determined by the pinhole size is reduced strongly by defocusing the specimen. This characteristic of confocal system gives us a chance to make optical sectioning with high vertical resolution discrimination by suppressing the scattered light from defocused object position. It is also well known that confocal microscopy gives some improvements in the sense of lateral resolution compared to the classical microscopy. (DMDTM) technology was developed by Texas Instruments. The DMD that used in the setup consists of 600x800 programmable micromirrors. Each of these mirrors has 16μm x 16μm square size with a 1μm gap between them and each mirror tilt ±10° around the diagonal axis with help of underlying memory cel. DMD as a member of MEMS device can also be used as a light switch. By combining the DMD with a suitable light source and optics, the DMD reflects the incoming beam either into or out of the microscope objective pupil by using a simple beam steering technique. By combining the light switch advantages of DMD unit with pulse width modulation application it is also possible to create gray scale operation, which can be used to obtain uniform illumination on CCD. By controlling the DMD pixels as an optical light switch any size and any shape pinholes, which are imaged through the optical system onto object where they are reflected and later imaged again onto CCD camera chip, can be created. On the CCD camera reflected intensities from the object are measured by the CCD pixels that are related with DMD’s “on” pixels. The measured intensities reach its maximum when the object is confocally in focus with the DMD and the CCD. Intensity data are measured and stored while the object is moving through the focal plane of the optical system. Finally maximum’s of the obtained intensity curves, which are also known as depth response curves, link to the corresponding motor position and the 3D profile of the specimen can be reconstructed. The advantages of the DMD based optical scanner can be listed as follows; conventional scanning devices such as Nipkow disk or tilting mirrors that introduce vibration and mechanical noises to system are eliminated, important flexibilities are introduced by DMD application, critical parameters such as pinhole size and pinhole shape can easily be changed, local illumination, which supplies uniform illumination on detector, can be introduced. The main challenges are differences between the images produced by the real illumination pinhole and the DMD, respectively, is the contrast ratio. The ground level intensity of the DMD image is higher because of stray light from the mirror edges and the protective glass layer. At the same time, the maximum intensity is lower because of transmission loss through the glass and reflection loss of the mirror elements. However, although the contrast ratio is worse with a DMD, the depth response curves taken with a regular pinhole and with a DMD show perfect comparability. This new microscope offers unique flexibility for pinhole size and shape that existing system can not do. It is also showed that the measurement results of the developed system are comparable with the stylus instruments and DMD based optical systems are an alternative to tactile techniques.