An　optical　apparatus　was　proposed　in　this　paper　that　allows　simultaneously　equal-optical-path　imaging　of　both　front　and　rear　end　surfaces　of　the　thermoelectric　cooler　(TEC)　components.　This　optical　apparatus　can　be　used　to　simultaneously　inspect　surface　defects　on　both　front　and　rear　end　surfaces　in　the　traveling　direction　of　the　TEC　components.　Two　sets　of　right-angle　relay　prisms　and　one　image　combiner　are　used　to　build　an　optical　apparatus　for　simultaneously　equal-optical-path　imaging　of　both　front　and　rear　end　surfaces　of　TEC　components.　The　experiments　of　defects　inspecting　both　front　and　rear　end　surfaces　of　the　TEC　components　were　carried　out.　The　inspecting　apparatus　was　used　to　collect　10,　000　images　and　the　ResNet50　deep　residual　learning　network　was　used　to　extract　and　learn　its　features.　The　accuracy　of　the　trained　model　of　94.8%　was　obtained　and　the　average　inspection　time　for　a　single　image　was　around　58ms.　The　experimental　results　show　that　the　proposed　optical　inspecting　apparatus　can　ensure　the　clear　imaging　of　TEC　components　on　both　front　and　rear　end　surfaces　on　the　CMOS　sensor.　It　meets　the　requirements　of　TEC　components　end　surface　defects　inspection　and　simplifies　the　system　configuration,　reduces　the　system　cost,　and　improves　the　system　reliability.　©　2023　SPIE.